ImageReader (Java SE 15 & JDK 15)
Description: declaration: module: java.desktop, package: javax.imageio, class: ImageReader
Keywords: javax.imageio.ImageReader class

Module java.desktop
Package javax.imageio

# Class ImageReader

java.lang.Object
javax.imageio.ImageReader

    public abstract class ImageReader
    extends Object

An abstract superclass for parsing and decoding of images. This class must be subclassed by classes that read in images in the context of the Java Image I/O framework.

`ImageReader` objects are normally instantiated by the service provider interface (SPI) class for the specific format. Service provider classes (e.g., instances of `ImageReaderSpi`) are registered with the `IIORegistry`, which uses them for format recognition and presentation of available format readers and writers.

When an input source is set (using the `setInput` method), it may be marked as "seek forward only". This setting means that images contained within the input source will only be read in order, possibly allowing the reader to avoid caching portions of the input containing data associated with images that have been read previously.

See Also:
  `ImageWriter`, `IIORegistry`, `ImageReaderSpi`

- ## Field Summary

  Fields
  Modifier and Type | Field | Description
  --- | --- | ---
  `protected Locale[]` | `availableLocales` | An array of `Locale`s which may be used to localize warning messages, or `null` if localization is not supported.
  `protected boolean` | `ignoreMetadata` | `true` if the current input source has been marked as allowing metadata to be ignored by `setInput`.
  `protected Object` | `input` | The `ImageInputStream` or other `Object` by `setInput` and retrieved by `getInput`.
  `protected Locale` | `locale` | The current `Locale` to be used for localization, or `null` if none has been set.
  `protected int` | `minIndex` | The smallest valid index for reading, initially 0.
  `protected ImageReaderSpi` | `originatingProvider` | The `ImageReaderSpi` that instantiated this object, or `null` if its identity is not known or none exists.
  `protected List<IIOReadProgressListener>` | `progressListeners` | A `List` of currently registered `IIOReadProgressListener`s, initialized by default to `null`, which is synonymous with an empty `List`.
  `protected boolean` | `seekForwardOnly` | `true` if the current input source has been marked as allowing only forward seeking by `setInput`.
  `protected List<IIOReadUpdateListener>` | `updateListeners` | A `List` of currently registered `IIOReadUpdateListener`s, initialized by default to `null`, which is synonymous with an empty `List`.
  `protected List<IIOReadWarningListener>` | `warningListeners` | A `List` of currently registered `IIOReadWarningListener`s, initialized by default to `null`, which is synonymous with an empty `List`.
  `protected List<Locale>` | `warningLocales` | A `List` of the `Locale`s associated with each currently registered `IIOReadWarningListener`, initialized by default to `null`, which is synonymous with an empty `List`.

- ## Constructor Summary

  Constructors
  Modifier | Constructor | Description
  --- | --- | ---
  `protected` | `ImageReader​(ImageReaderSpi originatingProvider)` | Constructs an `ImageReader` and sets its `originatingProvider` field to the supplied value.

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `void` | `abort()` | Requests that any current read operation be aborted.
  `protected boolean` | `abortRequested()` | Returns `true` if a request to abort the current read operation has been made since the reader was instantiated or `clearAbortRequest` was called.
  `void` | `addIIOReadProgressListener​(IIOReadProgressListener listener)` | Adds an `IIOReadProgressListener` to the list of registered progress listeners.
  `void` | `addIIOReadUpdateListener​(IIOReadUpdateListener listener)` | Adds an `IIOReadUpdateListener` to the list of registered update listeners.
  `void` | `addIIOReadWarningListener​(IIOReadWarningListener listener)` | Adds an `IIOReadWarningListener` to the list of registered warning listeners.
  `boolean` | `canReadRaster()` | Returns `true` if this plug-in supports reading just a `Raster` of pixel data.
  `protected static void` | `checkReadParamBandSettings​(ImageReadParam param, int numSrcBands, int numDstBands)` | A utility method that may be used by readers to test the validity of the source and destination band settings of an `ImageReadParam`.
  `protected void` | `clearAbortRequest()` | Clears any previous abort request.
  `protected static void` | `computeRegions​(ImageReadParam param, int srcWidth, int srcHeight, BufferedImage image, Rectangle srcRegion, Rectangle destRegion)` | Computes the source region of interest and the destination region of interest, taking the width and height of the source image, an optional destination image, and an optional `ImageReadParam` into account.
  `void` | `dispose()` | Allows any resources held by this object to be released.
  `float` | `getAspectRatio​(int imageIndex)` | Returns the aspect ratio of the given image (that is, its width divided by its height) as a `float`.
  `Locale[]` | `getAvailableLocales()` | Returns an array of `Locale`s that may be used to localize warning listeners and compression settings.
  `ImageReadParam` | `getDefaultReadParam()` | Returns a default `ImageReadParam` object appropriate for this format.
  `protected static BufferedImage` | `getDestination​(ImageReadParam param, Iterator<ImageTypeSpecifier> imageTypes, int width, int height)` | Returns the `BufferedImage` to which decoded pixel data should be written.
  `String` | `getFormatName()` | Returns a `String` identifying the format of the input source.
  `abstract int` | `getHeight​(int imageIndex)` | Returns the height in pixels of the given image within the input source.
  `abstract IIOMetadata` | `getImageMetadata​(int imageIndex)` | Returns an `IIOMetadata` object containing metadata associated with the given image, or `null` if the reader does not support reading metadata, is set to ignore metadata, or if no metadata is available.
  `IIOMetadata` | `getImageMetadata​(int imageIndex, String formatName, Set<String> nodeNames)` | Returns an `IIOMetadata` object representing the metadata associated with the given image, or `null` if the reader does not support reading metadata or none is available.
  `abstract Iterator<ImageTypeSpecifier>` | `getImageTypes​(int imageIndex)` | Returns an `Iterator` containing possible image types to which the given image may be decoded, in the form of `ImageTypeSpecifiers`s.
  `Object` | `getInput()` | Returns the `ImageInputStream` or other `Object` previously set as the input source.
  `Locale` | `getLocale()` | Returns the currently set `Locale`, or `null` if none has been set.
  `int` | `getMinIndex()` | Returns the lowest valid index for reading an image, thumbnail, or image metadata.
  `abstract int` | `getNumImages​(boolean allowSearch)` | Returns the number of images, not including thumbnails, available from the current input source.
  `int` | `getNumThumbnails​(int imageIndex)` | Returns the number of thumbnail preview images associated with the given image.
  `ImageReaderSpi` | `getOriginatingProvider()` | Returns the `ImageReaderSpi` that was passed in on the constructor.
  `ImageTypeSpecifier` | `getRawImageType​(int imageIndex)` | Returns an `ImageTypeSpecifier` indicating the `SampleModel` and `ColorModel` which most closely represents the "raw" internal format of the image.
  `protected static Rectangle` | `getSourceRegion​(ImageReadParam param, int srcWidth, int srcHeight)` | A utility method that may be used by readers to compute the region of the source image that should be read, taking into account any source region and subsampling offset settings in the supplied `ImageReadParam`.
  `abstract IIOMetadata` | `getStreamMetadata()` | Returns an `IIOMetadata` object representing the metadata associated with the input source as a whole (i.e., not associated with any particular image), or `null` if the reader does not support reading metadata, is set to ignore metadata, or if no metadata is available.
  `IIOMetadata` | `getStreamMetadata​(String formatName, Set<String> nodeNames)` | Returns an `IIOMetadata` object representing the metadata associated with the input source as a whole (i.e., not associated with any particular image).
  `int` | `getThumbnailHeight​(int imageIndex, int thumbnailIndex)` | Returns the height of the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex`.
  `int` | `getThumbnailWidth​(int imageIndex, int thumbnailIndex)` | Returns the width of the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex`.
  `int` | `getTileGridXOffset​(int imageIndex)` | Returns the X coordinate of the upper-left corner of tile (0, 0) in the given image.
  `int` | `getTileGridYOffset​(int imageIndex)` | Returns the Y coordinate of the upper-left corner of tile (0, 0) in the given image.
  `int` | `getTileHeight​(int imageIndex)` | Returns the height of a tile in the given image.
  `int` | `getTileWidth​(int imageIndex)` | Returns the width of a tile in the given image.
  `abstract int` | `getWidth​(int imageIndex)` | Returns the width in pixels of the given image within the input source.
  `boolean` | `hasThumbnails​(int imageIndex)` | Returns `true` if the given image has thumbnail preview images associated with it.
  `boolean` | `isIgnoringMetadata()` | Returns `true` if the current input source has been marked as allowing metadata to be ignored by passing `true` as the `ignoreMetadata` argument to the `setInput` method.
  `boolean` | `isImageTiled​(int imageIndex)` | Returns `true` if the image is organized into tiles, that is, equal-sized non-overlapping rectangles.
  `boolean` | `isRandomAccessEasy​(int imageIndex)` | Returns `true` if the storage format of the given image places no inherent impediment on random access to pixels.
  `boolean` | `isSeekForwardOnly()` | Returns `true` if the current input source has been marked as seek forward only by passing `true` as the `seekForwardOnly` argument to the `setInput` method.
  `protected void` | `processImageComplete()` | Broadcasts the completion of an image read to all registered `IIOReadProgressListener`s by calling their `imageComplete` method.
  `protected void` | `processImageProgress​(float percentageDone)` | Broadcasts the current percentage of image completion to all registered `IIOReadProgressListener`s by calling their `imageProgress` method.
  `protected void` | `processImageStarted​(int imageIndex)` | Broadcasts the start of an image read to all registered `IIOReadProgressListener`s by calling their `imageStarted` method.
  `protected void` | `processImageUpdate​(BufferedImage theImage, int minX, int minY, int width, int height, int periodX, int periodY, int[] bands)` | Broadcasts the update of a set of samples to all registered `IIOReadUpdateListener`s by calling their `imageUpdate` method.
  `protected void` | `processPassComplete​(BufferedImage theImage)` | Broadcasts the end of a progressive pass to all registered `IIOReadUpdateListener`s by calling their `passComplete` method.
  `protected void` | `processPassStarted​(BufferedImage theImage, int pass, int minPass, int maxPass, int minX, int minY, int periodX, int periodY, int[] bands)` | Broadcasts the beginning of a progressive pass to all registered `IIOReadUpdateListener`s by calling their `passStarted` method.
  `protected void` | `processReadAborted()` | Broadcasts that the read has been aborted to all registered `IIOReadProgressListener`s by calling their `readAborted` method.
  `protected void` | `processSequenceComplete()` | Broadcasts the completion of an sequence of image reads to all registered `IIOReadProgressListener`s by calling their `sequenceComplete` method.
  `protected void` | `processSequenceStarted​(int minIndex)` | Broadcasts the start of an sequence of image reads to all registered `IIOReadProgressListener`s by calling their `sequenceStarted` method.
  `protected void` | `processThumbnailComplete()` | Broadcasts the completion of a thumbnail read to all registered `IIOReadProgressListener`s by calling their `thumbnailComplete` method.
  `protected void` | `processThumbnailPassComplete​(BufferedImage theThumbnail)` | Broadcasts the end of a thumbnail progressive pass to all registered `IIOReadUpdateListener`s by calling their `thumbnailPassComplete` method.
  `protected void` | `processThumbnailPassStarted​(BufferedImage theThumbnail, int pass, int minPass, int maxPass, int minX, int minY, int periodX, int periodY, int[] bands)` | Broadcasts the beginning of a thumbnail progressive pass to all registered `IIOReadUpdateListener`s by calling their `thumbnailPassStarted` method.
  `protected void` | `processThumbnailProgress​(float percentageDone)` | Broadcasts the current percentage of thumbnail completion to all registered `IIOReadProgressListener`s by calling their `thumbnailProgress` method.
  `protected void` | `processThumbnailStarted​(int imageIndex, int thumbnailIndex)` | Broadcasts the start of a thumbnail read to all registered `IIOReadProgressListener`s by calling their `thumbnailStarted` method.
  `protected void` | `processThumbnailUpdate​(BufferedImage theThumbnail, int minX, int minY, int width, int height, int periodX, int periodY, int[] bands)` | Broadcasts the update of a set of samples in a thumbnail image to all registered `IIOReadUpdateListener`s by calling their `thumbnailUpdate` method.
  `protected void` | `processWarningOccurred​(String warning)` | Broadcasts a warning message to all registered `IIOReadWarningListener`s by calling their `warningOccurred` method.
  `protected void` | `processWarningOccurred​(String baseName, String keyword)` | Broadcasts a localized warning message to all registered `IIOReadWarningListener`s by calling their `warningOccurred` method with a string taken from a `ResourceBundle`.
  `BufferedImage` | `read​(int imageIndex)` | Reads the image indexed by `imageIndex` and returns it as a complete `BufferedImage`, using a default `ImageReadParam`.
  `abstract BufferedImage` | `read​(int imageIndex, ImageReadParam param)` | Reads the image indexed by `imageIndex` and returns it as a complete `BufferedImage`, using a supplied `ImageReadParam`.
  `IIOImage` | `readAll​(int imageIndex, ImageReadParam param)` | Reads the image indexed by `imageIndex` and returns an `IIOImage` containing the image, thumbnails, and associated image metadata, using a supplied `ImageReadParam`.
  `Iterator<IIOImage>` | `readAll​(Iterator<? extends ImageReadParam> params)` | Returns an `Iterator` containing all the images, thumbnails, and metadata, starting at the index given by `getMinIndex`, from the input source in the form of `IIOImage` objects.
  `RenderedImage` | `readAsRenderedImage​(int imageIndex, ImageReadParam param)` | Returns a `RenderedImage` object that contains the contents of the image indexed by `imageIndex`.
  `boolean` | `readerSupportsThumbnails()` | Returns `true` if the image format understood by this reader supports thumbnail preview images associated with it.
  `Raster` | `readRaster​(int imageIndex, ImageReadParam param)` | Returns a new `Raster` object containing the raw pixel data from the image stream, without any color conversion applied.
  `BufferedImage` | `readThumbnail​(int imageIndex, int thumbnailIndex)` | Returns the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex` as a `BufferedImage`.
  `BufferedImage` | `readTile​(int imageIndex, int tileX, int tileY)` | Reads the tile indicated by the `tileX` and `tileY` arguments, returning it as a `BufferedImage`.
  `Raster` | `readTileRaster​(int imageIndex, int tileX, int tileY)` | Returns a new `Raster` object containing the raw pixel data from the tile, without any color conversion applied.
  `void` | `removeAllIIOReadProgressListeners()` | Removes all currently registered `IIOReadProgressListener` objects.
  `void` | `removeAllIIOReadUpdateListeners()` | Removes all currently registered `IIOReadUpdateListener` objects.
  `void` | `removeAllIIOReadWarningListeners()` | Removes all currently registered `IIOReadWarningListener` objects.
  `void` | `removeIIOReadProgressListener​(IIOReadProgressListener listener)` | Removes an `IIOReadProgressListener` from the list of registered progress listeners.
  `void` | `removeIIOReadUpdateListener​(IIOReadUpdateListener listener)` | Removes an `IIOReadUpdateListener` from the list of registered update listeners.
  `void` | `removeIIOReadWarningListener​(IIOReadWarningListener listener)` | Removes an `IIOReadWarningListener` from the list of registered error listeners.
  `void` | `reset()` | Restores the `ImageReader` to its initial state.
  `void` | `setInput​(Object input)` | Sets the input source to use to the given `ImageInputStream` or other `Object`.
  `void` | `setInput​(Object input, boolean seekForwardOnly)` | Sets the input source to use to the given `ImageInputStream` or other `Object`.
  `void` | `setInput​(Object input, boolean seekForwardOnly, boolean ignoreMetadata)` | Sets the input source to use to the given `ImageInputStream` or other `Object`.
  `void` | `setLocale​(Locale locale)` | Sets the current `Locale` of this `ImageReader` to the given value.

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### originatingProvider

    protected ImageReaderSpi originatingProvider
    The `ImageReaderSpi` that instantiated this object, or `null` if its identity is not known or none exists. By default it is initialized to `null`.

  - ### input

    protected Object input
    The `ImageInputStream` or other `Object` by `setInput` and retrieved by `getInput`. By default it is initialized to `null`.

  - ### seekForwardOnly

    protected boolean seekForwardOnly
    `true` if the current input source has been marked as allowing only forward seeking by `setInput`. By default, the value is `false`.
    See Also:
      `minIndex`, `setInput(java.lang.Object, boolean, boolean)`

  - ### ignoreMetadata

    protected boolean ignoreMetadata
    `true` if the current input source has been marked as allowing metadata to be ignored by `setInput`. By default, the value is `false`.
    See Also:
      `setInput(java.lang.Object, boolean, boolean)`

  - ### minIndex

    protected int minIndex
    The smallest valid index for reading, initially 0. When `seekForwardOnly` is `true`, various methods may throw an `IndexOutOfBoundsException` on an attempt to access data associate with an image having a lower index.
    See Also:
      `seekForwardOnly`, `setInput(java.lang.Object, boolean, boolean)`

  - ### availableLocales

    protected Locale[] availableLocales
    An array of `Locale`s which may be used to localize warning messages, or `null` if localization is not supported.

  - ### locale

    protected Locale locale
    The current `Locale` to be used for localization, or `null` if none has been set.

  - ### warningListeners

    protected List<IIOReadWarningListener> warningListeners
    A `List` of currently registered `IIOReadWarningListener`s, initialized by default to `null`, which is synonymous with an empty `List`.

  - ### warningLocales

    protected List<Locale> warningLocales
    A `List` of the `Locale`s associated with each currently registered `IIOReadWarningListener`, initialized by default to `null`, which is synonymous with an empty `List`.

  - ### progressListeners

    protected List<IIOReadProgressListener> progressListeners
    A `List` of currently registered `IIOReadProgressListener`s, initialized by default to `null`, which is synonymous with an empty `List`.

  - ### updateListeners

    protected List<IIOReadUpdateListener> updateListeners
    A `List` of currently registered `IIOReadUpdateListener`s, initialized by default to `null`, which is synonymous with an empty `List`.

- ## Constructor Details

  - ### ImageReader

    protected ImageReader​(ImageReaderSpi originatingProvider)
    Constructs an `ImageReader` and sets its `originatingProvider` field to the supplied value.

    Subclasses that make use of extensions should provide a constructor with signature `(ImageReaderSpi,Object)` in order to retrieve the extension object. If the extension object is unsuitable, an `IllegalArgumentException` should be thrown.

    Parameters:
      `originatingProvider` - the `ImageReaderSpi` that is invoking this constructor, or `null`.

- ## Method Details

  - ### getFormatName

    public String getFormatName() throws IOException
    Returns a `String` identifying the format of the input source.

    The default implementation returns `originatingProvider.getFormatNames()[0]`. Implementations that may not have an originating service provider, or which desire a different naming policy should override this method.

    Returns:
      the format name, as a `String`.
    Throws:
      `IOException` - if an error occurs reading the information from the input source.

  - ### getOriginatingProvider

    public ImageReaderSpi getOriginatingProvider()
    Returns the `ImageReaderSpi` that was passed in on the constructor. Note that this value may be `null`.
    Returns:
      an `ImageReaderSpi`, or `null`.
    See Also:
      `ImageReaderSpi`

  - ### setInput

    public void setInput​(Object input, boolean seekForwardOnly, boolean ignoreMetadata)
    Sets the input source to use to the given `ImageInputStream` or other `Object`. The input source must be set before any of the query or read methods are used. If `input` is `null`, any currently set input source will be removed. In any case, the value of `minIndex` will be initialized to 0.

    The `seekForwardOnly` parameter controls whether the value returned by `getMinIndex` will be increased as each image (or thumbnail, or image metadata) is read. If `seekForwardOnly` is true, then a call to `read(index)` will throw an `IndexOutOfBoundsException` if `index < this.minIndex`; otherwise, the value of `minIndex` will be set to `index`. If `seekForwardOnly` is `false`, the value of `minIndex` will remain 0 regardless of any read operations.

    The `ignoreMetadata` parameter, if set to `true`, allows the reader to disregard any metadata encountered during the read. Subsequent calls to the `getStreamMetadata` and `getImageMetadata` methods may return `null`, and an `IIOImage` returned from `readAll` may return `null` from their `getMetadata` method. Setting this parameter may allow the reader to work more efficiently. The reader may choose to disregard this setting and return metadata normally.

    Subclasses should take care to remove any cached information based on the previous stream, such as header information or partially decoded image data.

    Use of a general `Object` other than an `ImageInputStream` is intended for readers that interact directly with a capture device or imaging protocol. The set of legal classes is advertised by the reader's service provider's `getInputTypes` method; most readers will return a single-element array containing only `ImageInputStream.class` to indicate that they accept only an `ImageInputStream`.

    The default implementation checks the `input` argument against the list returned by `originatingProvider.getInputTypes()` and fails if the argument is not an instance of one of the classes in the list. If the originating provider is set to `null`, the input is accepted only if it is an `ImageInputStream`.

    Parameters:
      `input` - the `ImageInputStream` or other `Object` to use for future decoding.
      `seekForwardOnly` - if `true`, images and metadata may only be read in ascending order from this input source.
      `ignoreMetadata` - if `true`, metadata may be ignored during reads.
    Throws:
      `IllegalArgumentException` - if `input` is not an instance of one of the classes returned by the originating service provider's `getInputTypes` method, or is not an `ImageInputStream`.
    See Also:
      `ImageInputStream`, `getInput()`, `ImageReaderSpi.getInputTypes()`

  - ### setInput

    public void setInput​(Object input, boolean seekForwardOnly)
    Sets the input source to use to the given `ImageInputStream` or other `Object`. The input source must be set before any of the query or read methods are used. If `input` is `null`, any currently set input source will be removed. In any case, the value of `minIndex` will be initialized to 0.

    The `seekForwardOnly` parameter controls whether the value returned by `getMinIndex` will be increased as each image (or thumbnail, or image metadata) is read. If `seekForwardOnly` is true, then a call to `read(index)` will throw an `IndexOutOfBoundsException` if `index < this.minIndex`; otherwise, the value of `minIndex` will be set to `index`. If `seekForwardOnly` is `false`, the value of `minIndex` will remain 0 regardless of any read operations.

    This method is equivalent to `setInput(input, seekForwardOnly, false)`.

    Parameters:
      `input` - the `ImageInputStream` or other `Object` to use for future decoding.
      `seekForwardOnly` - if `true`, images and metadata may only be read in ascending order from this input source.
    Throws:
      `IllegalArgumentException` - if `input` is not an instance of one of the classes returned by the originating service provider's `getInputTypes` method, or is not an `ImageInputStream`.
    See Also:
      `getInput()`

  - ### setInput

    public void setInput​(Object input)
    Sets the input source to use to the given `ImageInputStream` or other `Object`. The input source must be set before any of the query or read methods are used. If `input` is `null`, any currently set input source will be removed. In any case, the value of `minIndex` will be initialized to 0.

    This method is equivalent to `setInput(input, false, false)`.

    Parameters:
      `input` - the `ImageInputStream` or other `Object` to use for future decoding.
    Throws:
      `IllegalArgumentException` - if `input` is not an instance of one of the classes returned by the originating service provider's `getInputTypes` method, or is not an `ImageInputStream`.
    See Also:
      `getInput()`

  - ### getInput

    public Object getInput()
    Returns the `ImageInputStream` or other `Object` previously set as the input source. If the input source has not been set, `null` is returned.
    Returns:
      the `Object` that will be used for future decoding, or `null`.
    See Also:
      `ImageInputStream`, `setInput(java.lang.Object, boolean, boolean)`

  - ### isSeekForwardOnly

    public boolean isSeekForwardOnly()
    Returns `true` if the current input source has been marked as seek forward only by passing `true` as the `seekForwardOnly` argument to the `setInput` method.
    Returns:
      `true` if the input source is seek forward only.
    See Also:
      `setInput(java.lang.Object, boolean, boolean)`

  - ### isIgnoringMetadata

    public boolean isIgnoringMetadata()
    Returns `true` if the current input source has been marked as allowing metadata to be ignored by passing `true` as the `ignoreMetadata` argument to the `setInput` method.
    Returns:
      `true` if the metadata may be ignored.
    See Also:
      `setInput(java.lang.Object, boolean, boolean)`

  - ### getMinIndex

    public int getMinIndex()
    Returns the lowest valid index for reading an image, thumbnail, or image metadata. If `seekForwardOnly()` is `false`, this value will typically remain 0, indicating that random access is possible. Otherwise, it will contain the value of the most recently accessed index, and increase in a monotonic fashion.
    Returns:
      the minimum legal index for reading.

  - ### getAvailableLocales

    public Locale[] getAvailableLocales()
    Returns an array of `Locale`s that may be used to localize warning listeners and compression settings. A return value of `null` indicates that localization is not supported.

    The default implementation returns a clone of the `availableLocales` instance variable if it is non-`null`, or else returns `null`.

    Returns:
      an array of `Locale`s that may be used as arguments to `setLocale`, or `null`.

  - ### setLocale

    public void setLocale​(Locale locale)
    Sets the current `Locale` of this `ImageReader` to the given value. A value of `null` removes any previous setting, and indicates that the reader should localize as it sees fit.
    Parameters:
      `locale` - the desired `Locale`, or `null`.
    Throws:
      `IllegalArgumentException` - if `locale` is non-`null` but is not one of the values returned by `getAvailableLocales`.
    See Also:
      `getLocale()`

  - ### getLocale

    public Locale getLocale()
    Returns the currently set `Locale`, or `null` if none has been set.
    Returns:
      the current `Locale`, or `null`.
    See Also:
      `setLocale(java.util.Locale)`

  - ### getNumImages

    public abstract int getNumImages​(boolean allowSearch) throws IOException
    Returns the number of images, not including thumbnails, available from the current input source.

    Note that some image formats (such as animated GIF) do not specify how many images are present in the stream. Thus determining the number of images will require the entire stream to be scanned and may require memory for buffering. If images are to be processed in order, it may be more efficient to simply call `read` with increasing indices until an `IndexOutOfBoundsException` is thrown to indicate that no more images are available. The `allowSearch` parameter may be set to `false` to indicate that an exhaustive search is not desired; the return value will be `-1` to indicate that a search is necessary. If the input has been specified with `seekForwardOnly` set to `true`, this method throws an `IllegalStateException` if `allowSearch` is set to `true`.

    Parameters:
      `allowSearch` - if `true`, the true number of images will be returned even if a search is required. If `false`, the reader may return `-1` without performing the search.
    Returns:
      the number of images, as an `int`, or `-1` if `allowSearch` is `false` and a search would be required.
    Throws:
      `IllegalStateException` - if the input source has not been set, or if the input has been specified with `seekForwardOnly` set to `true`.
      `IOException` - if an error occurs reading the information from the input source.
    See Also:
      `setInput(java.lang.Object, boolean, boolean)`

  - ### getWidth

    public abstract int getWidth​(int imageIndex) throws IOException
    Returns the width in pixels of the given image within the input source.

    If the image can be rendered to a user-specified size, then this method returns the default width.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the width of the image, as an `int`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs reading the width information from the input source.

  - ### getHeight

    public abstract int getHeight​(int imageIndex) throws IOException
    Returns the height in pixels of the given image within the input source.

    If the image can be rendered to a user-specified size, then this method returns the default height.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the height of the image, as an `int`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs reading the height information from the input source.

  - ### isRandomAccessEasy

    public boolean isRandomAccessEasy​(int imageIndex) throws IOException
    Returns `true` if the storage format of the given image places no inherent impediment on random access to pixels. For most compressed formats, such as JPEG, this method should return `false`, as a large section of the image in addition to the region of interest may need to be decoded.

    This is merely a hint for programs that wish to be efficient; all readers must be able to read arbitrary regions as specified in an `ImageReadParam`.

    Note that formats that return `false` from this method may nonetheless allow tiling (e.g. Restart Markers in JPEG), and random access will likely be reasonably efficient on tiles. See `isImageTiled`.

    A reader for which all images are guaranteed to support easy random access, or are guaranteed not to support easy random access, may return `true` or `false` respectively without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.

    The default implementation returns `false`.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      `true` if reading a region of interest of the given image is likely to be efficient.
    Throws:
      `IllegalStateException` - if an input source is required to determine the return value, but none has been set.
      `IndexOutOfBoundsException` - if an image must be accessed to determine the return value, but the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getAspectRatio

    public float getAspectRatio​(int imageIndex) throws IOException
    Returns the aspect ratio of the given image (that is, its width divided by its height) as a `float`. For images that are inherently resizable, this method provides a way to determine the appropriate width given a desired height, or vice versa. For non-resizable images, the true width and height are used.

    The default implementation simply returns `(float)getWidth(imageIndex)/getHeight(imageIndex)`.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      a `float` indicating the aspect ratio of the given image.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getRawImageType

    public ImageTypeSpecifier getRawImageType​(int imageIndex) throws IOException
    Returns an `ImageTypeSpecifier` indicating the `SampleModel` and `ColorModel` which most closely represents the "raw" internal format of the image. If there is no close match then a type which preserves the most information from the image should be returned. The returned value should also be included in the list of values returned by `getImageTypes`.

    The default implementation simply returns the first entry from the list provided by `getImageType`.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      an `ImageTypeSpecifier`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs reading the format information from the input source.

  - ### getImageTypes

    public abstract Iterator<ImageTypeSpecifier> getImageTypes​(int imageIndex) throws IOException
    Returns an `Iterator` containing possible image types to which the given image may be decoded, in the form of `ImageTypeSpecifiers`s. At least one legal image type will be returned.

    The first element of the iterator should be the most "natural" type for decoding the image with as little loss as possible. For example, for a JPEG image the first entry should be an RGB image, even though the image data is stored internally in a YCbCr color space.

    Parameters:
      `imageIndex` - the index of the image to be `retrieved`.
    Returns:
      an `Iterator` containing at least one `ImageTypeSpecifier` representing suggested image types for decoding the current given image.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs reading the format information from the input source.
    See Also:
      `ImageReadParam.setDestination(BufferedImage)`, `IIOParam.setDestinationType(ImageTypeSpecifier)`

  - ### getDefaultReadParam

    public ImageReadParam getDefaultReadParam()
    Returns a default `ImageReadParam` object appropriate for this format. All subclasses should define a set of default values for all parameters and return them with this call. This method may be called before the input source is set.

    The default implementation constructs and returns a new `ImageReadParam` object that does not allow source scaling (i.e., it returns `new ImageReadParam()`.

    Returns:
      an `ImageReadParam` object which may be used to control the decoding process using a set of default settings.

  - ### getStreamMetadata

    public abstract IIOMetadata getStreamMetadata() throws IOException
    Returns an `IIOMetadata` object representing the metadata associated with the input source as a whole (i.e., not associated with any particular image), or `null` if the reader does not support reading metadata, is set to ignore metadata, or if no metadata is available.
    Returns:
      an `IIOMetadata` object, or `null`.
    Throws:
      `IOException` - if an error occurs during reading.

  - ### getStreamMetadata

    public IIOMetadata getStreamMetadata​(String formatName, Set<String> nodeNames) throws IOException
    Returns an `IIOMetadata` object representing the metadata associated with the input source as a whole (i.e., not associated with any particular image). If no such data exists, `null` is returned.

    The resulting metadata object is only responsible for returning documents in the format named by `formatName`. Within any documents that are returned, only nodes whose names are members of `nodeNames` are required to be returned. In this way, the amount of metadata processing done by the reader may be kept to a minimum, based on what information is actually needed.

    If `formatName` is not the name of a supported metadata format, `null` is returned.

    In all cases, it is legal to return a more capable metadata object than strictly necessary. The format name and node names are merely hints that may be used to reduce the reader's workload.

    The default implementation simply returns the result of calling `getStreamMetadata()`, after checking that the format name is supported. If it is not, `null` is returned.

    Parameters:
      `formatName` - a metadata format name that may be used to retrieve a document from the returned `IIOMetadata` object.
      `nodeNames` - a `Set` containing the names of nodes that may be contained in a retrieved document.
    Returns:
      an `IIOMetadata` object, or `null`.
    Throws:
      `IllegalArgumentException` - if `formatName` is `null`.
      `IllegalArgumentException` - if `nodeNames` is `null`.
      `IOException` - if an error occurs during reading.

  - ### getImageMetadata

    public abstract IIOMetadata getImageMetadata​(int imageIndex) throws IOException
    Returns an `IIOMetadata` object containing metadata associated with the given image, or `null` if the reader does not support reading metadata, is set to ignore metadata, or if no metadata is available.
    Parameters:
      `imageIndex` - the index of the image whose metadata is to be retrieved.
    Returns:
      an `IIOMetadata` object, or `null`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getImageMetadata

    public IIOMetadata getImageMetadata​(int imageIndex, String formatName, Set<String> nodeNames) throws IOException
    Returns an `IIOMetadata` object representing the metadata associated with the given image, or `null` if the reader does not support reading metadata or none is available.

    The resulting metadata object is only responsible for returning documents in the format named by `formatName`. Within any documents that are returned, only nodes whose names are members of `nodeNames` are required to be returned. In this way, the amount of metadata processing done by the reader may be kept to a minimum, based on what information is actually needed.

    If `formatName` is not the name of a supported metadata format, `null` may be returned.

    In all cases, it is legal to return a more capable metadata object than strictly necessary. The format name and node names are merely hints that may be used to reduce the reader's workload.

    The default implementation simply returns the result of calling `getImageMetadata(imageIndex)`, after checking that the format name is supported. If it is not, `null` is returned.

    Parameters:
      `imageIndex` - the index of the image whose metadata is to be retrieved.
      `formatName` - a metadata format name that may be used to retrieve a document from the returned `IIOMetadata` object.
      `nodeNames` - a `Set` containing the names of nodes that may be contained in a retrieved document.
    Returns:
      an `IIOMetadata` object, or `null`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IllegalArgumentException` - if `formatName` is `null`.
      `IllegalArgumentException` - if `nodeNames` is `null`.
      `IOException` - if an error occurs during reading.

  - ### read

    public BufferedImage read​(int imageIndex) throws IOException
    Reads the image indexed by `imageIndex` and returns it as a complete `BufferedImage`, using a default `ImageReadParam`. This is a convenience method that calls `read(imageIndex, null)`.

    The image returned will be formatted according to the first `ImageTypeSpecifier` returned from `getImageTypes`.

    Any registered `IIOReadProgressListener` objects will be notified by calling their `imageStarted` method, followed by calls to their `imageProgress` method as the read progresses. Finally their `imageComplete` method will be called. `IIOReadUpdateListener` objects may be updated at other times during the read as pixels are decoded. Finally, `IIOReadWarningListener` objects will receive notification of any non-fatal warnings that occur during decoding.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
    Returns:
      the desired portion of the image as a `BufferedImage`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### read

    public abstract BufferedImage read​(int imageIndex, ImageReadParam param) throws IOException
    Reads the image indexed by `imageIndex` and returns it as a complete `BufferedImage`, using a supplied `ImageReadParam`.

    The actual `BufferedImage` returned will be chosen using the algorithm defined by the `getDestination` method.

    Any registered `IIOReadProgressListener` objects will be notified by calling their `imageStarted` method, followed by calls to their `imageProgress` method as the read progresses. Finally their `imageComplete` method will be called. `IIOReadUpdateListener` objects may be updated at other times during the read as pixels are decoded. Finally, `IIOReadWarningListener` objects will receive notification of any non-fatal warnings that occur during decoding.

    The set of source bands to be read and destination bands to be written is determined by calling `getSourceBands` and `getDestinationBands` on the supplied `ImageReadParam`. If the lengths of the arrays returned by these methods differ, the set of source bands contains an index larger that the largest available source index, or the set of destination bands contains an index larger than the largest legal destination index, an `IllegalArgumentException` is thrown.

    If the supplied `ImageReadParam` contains optional setting values not supported by this reader (e.g. source render size or any format-specific settings), they will be ignored.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `param` - an `ImageReadParam` used to control the reading process, or `null`.
    Returns:
      the desired portion of the image as a `BufferedImage`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IllegalArgumentException` - if the set of source and destination bands specified by `param.getSourceBands` and `param.getDestinationBands` differ in length or include indices that are out of bounds.
      `IllegalArgumentException` - if the resulting image would have a width or height less than 1.
      `IOException` - if an error occurs during reading.

  - ### readAll

    public IIOImage readAll​(int imageIndex, ImageReadParam param) throws IOException
    Reads the image indexed by `imageIndex` and returns an `IIOImage` containing the image, thumbnails, and associated image metadata, using a supplied `ImageReadParam`.

    The actual `BufferedImage` referenced by the returned `IIOImage` will be chosen using the algorithm defined by the `getDestination` method.

    Any registered `IIOReadProgressListener` objects will be notified by calling their `imageStarted` method, followed by calls to their `imageProgress` method as the read progresses. Finally their `imageComplete` method will be called. `IIOReadUpdateListener` objects may be updated at other times during the read as pixels are decoded. Finally, `IIOReadWarningListener` objects will receive notification of any non-fatal warnings that occur during decoding.

    The set of source bands to be read and destination bands to be written is determined by calling `getSourceBands` and `getDestinationBands` on the supplied `ImageReadParam`. If the lengths of the arrays returned by these methods differ, the set of source bands contains an index larger that the largest available source index, or the set of destination bands contains an index larger than the largest legal destination index, an `IllegalArgumentException` is thrown.

    Thumbnails will be returned in their entirety regardless of the region settings.

    If the supplied `ImageReadParam` contains optional setting values not supported by this reader (e.g. source render size or any format-specific settings), those values will be ignored.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `param` - an `ImageReadParam` used to control the reading process, or `null`.
    Returns:
      an `IIOImage` containing the desired portion of the image, a set of thumbnails, and associated image metadata.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IllegalArgumentException` - if the set of source and destination bands specified by `param.getSourceBands` and `param.getDestinationBands` differ in length or include indices that are out of bounds.
      `IllegalArgumentException` - if the resulting image would have a width or height less than 1.
      `IOException` - if an error occurs during reading.

  - ### readAll

    public Iterator<IIOImage> readAll​(Iterator<? extends ImageReadParam> params) throws IOException
    Returns an `Iterator` containing all the images, thumbnails, and metadata, starting at the index given by `getMinIndex`, from the input source in the form of `IIOImage` objects. An `Iterator` containing `ImageReadParam` objects is supplied; one element is consumed for each image read from the input source until no more images are available. If the read param `Iterator` runs out of elements, but there are still more images available from the input source, default read params are used for the remaining images.

    If `params` is `null`, a default read param will be used for all images.

    The actual `BufferedImage` referenced by the returned `IIOImage` will be chosen using the algorithm defined by the `getDestination` method.

    Any registered `IIOReadProgressListener` objects will be notified by calling their `sequenceStarted` method once. Then, for each image decoded, there will be a call to `imageStarted`, followed by calls to `imageProgress` as the read progresses, and finally to `imageComplete`. The `sequenceComplete` method will be called after the last image has been decoded. `IIOReadUpdateListener` objects may be updated at other times during the read as pixels are decoded. Finally, `IIOReadWarningListener` objects will receive notification of any non-fatal warnings that occur during decoding.

    The set of source bands to be read and destination bands to be written is determined by calling `getSourceBands` and `getDestinationBands` on the supplied `ImageReadParam`. If the lengths of the arrays returned by these methods differ, the set of source bands contains an index larger that the largest available source index, or the set of destination bands contains an index larger than the largest legal destination index, an `IllegalArgumentException` is thrown.

    Thumbnails will be returned in their entirety regardless of the region settings.

    If any of the supplied `ImageReadParam`s contain optional setting values not supported by this reader (e.g. source render size or any format-specific settings), they will be ignored.

    Parameters:
      `params` - an `Iterator` containing `ImageReadParam` objects.
    Returns:
      an `Iterator` representing the contents of the input source as `IIOImage`s.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IllegalArgumentException` - if any non-`null` element of `params` is not an `ImageReadParam`.
      `IllegalArgumentException` - if the set of source and destination bands specified by `param.getSourceBands` and `param.getDestinationBands` differ in length or include indices that are out of bounds.
      `IllegalArgumentException` - if a resulting image would have a width or height less than 1.
      `IOException` - if an error occurs during reading.
    See Also:
      `ImageReadParam`, `IIOImage`

  - ### canReadRaster

    public boolean canReadRaster()
    Returns `true` if this plug-in supports reading just a `Raster` of pixel data. If this method returns `false`, calls to `readRaster` or `readTileRaster` will throw an `UnsupportedOperationException`.

    The default implementation returns `false`.

    Returns:
      `true` if this plug-in supports reading raw `Raster`s.
    See Also:
      `readRaster(int, javax.imageio.ImageReadParam)`, `readTileRaster(int, int, int)`

  - ### readRaster

    public Raster readRaster​(int imageIndex, ImageReadParam param) throws IOException
    Returns a new `Raster` object containing the raw pixel data from the image stream, without any color conversion applied. The application must determine how to interpret the pixel data by other means. Any destination or image-type parameters in the supplied `ImageReadParam` object are ignored, but all other parameters are used exactly as in the `read` method, except that any destination offset is used as a logical rather than a physical offset. The size of the returned `Raster` will always be that of the source region clipped to the actual image. Logical offsets in the stream itself are ignored.

    This method allows formats that normally apply a color conversion, such as JPEG, and formats that do not normally have an associated colorspace, such as remote sensing or medical imaging data, to provide access to raw pixel data.

    Any registered `readUpdateListener`s are ignored, as there is no `BufferedImage`, but all other listeners are called exactly as they are for the `read` method.

    If `canReadRaster()` returns `false`, this method throws an `UnsupportedOperationException`.

    If the supplied `ImageReadParam` contains optional setting values not supported by this reader (e.g. source render size or any format-specific settings), they will be ignored.

    The default implementation throws an `UnsupportedOperationException`.

    Parameters:
      `imageIndex` - the index of the image to be read.
      `param` - an `ImageReadParam` used to control the reading process, or `null`.
    Returns:
      the desired portion of the image as a `Raster`.
    Throws:
      `UnsupportedOperationException` - if this plug-in does not support reading raw `Raster`s.
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.
    See Also:
      `canReadRaster()`, `read(int)`, `Raster`

  - ### isImageTiled

    public boolean isImageTiled​(int imageIndex) throws IOException
    Returns `true` if the image is organized into tiles, that is, equal-sized non-overlapping rectangles.

    A reader plug-in may choose whether or not to expose tiling that is present in the image as it is stored. It may even choose to advertise tiling when none is explicitly present. In general, tiling should only be advertised if there is some advantage (in speed or space) to accessing individual tiles. Regardless of whether the reader advertises tiling, it must be capable of reading an arbitrary rectangular region specified in an `ImageReadParam`.

    A reader for which all images are guaranteed to be tiled, or are guaranteed not to be tiled, may return `true` or `false` respectively without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.

    The default implementation just returns `false`.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      `true` if the image is tiled.
    Throws:
      `IllegalStateException` - if an input source is required to determine the return value, but none has been set.
      `IndexOutOfBoundsException` - if an image must be accessed to determine the return value, but the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getTileWidth

    public int getTileWidth​(int imageIndex) throws IOException
    Returns the width of a tile in the given image.

    The default implementation simply returns `getWidth(imageIndex)`, which is correct for non-tiled images. Readers that support tiling should override this method.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the width of a tile.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getTileHeight

    public int getTileHeight​(int imageIndex) throws IOException
    Returns the height of a tile in the given image.

    The default implementation simply returns `getHeight(imageIndex)`, which is correct for non-tiled images. Readers that support tiling should override this method.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the height of a tile.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getTileGridXOffset

    public int getTileGridXOffset​(int imageIndex) throws IOException
    Returns the X coordinate of the upper-left corner of tile (0, 0) in the given image.

    A reader for which the tile grid X offset always has the same value (usually 0), may return the value without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.

    The default implementation simply returns 0, which is correct for non-tiled images and tiled images in most formats. Readers that support tiling with non-(0, 0) offsets should override this method.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the X offset of the tile grid.
    Throws:
      `IllegalStateException` - if an input source is required to determine the return value, but none has been set.
      `IndexOutOfBoundsException` - if an image must be accessed to determine the return value, but the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getTileGridYOffset

    public int getTileGridYOffset​(int imageIndex) throws IOException
    Returns the Y coordinate of the upper-left corner of tile (0, 0) in the given image.

    A reader for which the tile grid Y offset always has the same value (usually 0), may return the value without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.

    The default implementation simply returns 0, which is correct for non-tiled images and tiled images in most formats. Readers that support tiling with non-(0, 0) offsets should override this method.

    Parameters:
      `imageIndex` - the index of the image to be queried.
    Returns:
      the Y offset of the tile grid.
    Throws:
      `IllegalStateException` - if an input source is required to determine the return value, but none has been set.
      `IndexOutOfBoundsException` - if an image must be accessed to determine the return value, but the supplied index is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### readTile

    public BufferedImage readTile​(int imageIndex, int tileX, int tileY) throws IOException
    Reads the tile indicated by the `tileX` and `tileY` arguments, returning it as a `BufferedImage`. If the arguments are out of range, an `IllegalArgumentException` is thrown. If the image is not tiled, the values 0, 0 will return the entire image; any other values will cause an `IllegalArgumentException` to be thrown.

    This method is merely a convenience equivalent to calling `read(int, ImageReadParam)` with a read param specifying a source region having offsets of `tileX*getTileWidth(imageIndex)`, `tileY*getTileHeight(imageIndex)` and width and height of `getTileWidth(imageIndex)`, `getTileHeight(imageIndex)`; and subsampling factors of 1 and offsets of 0. To subsample a tile, call `read` with a read param specifying this region and different subsampling parameters.

    The default implementation returns the entire image if `tileX` and `tileY` are 0, or throws an `IllegalArgumentException` otherwise.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `tileX` - the column index (starting with 0) of the tile to be retrieved.
      `tileY` - the row index (starting with 0) of the tile to be retrieved.
    Returns:
      the tile as a `BufferedImage`.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if `imageIndex` is out of bounds.
      `IllegalArgumentException` - if the tile indices are out of bounds.
      `IOException` - if an error occurs during reading.

  - ### readTileRaster

    public Raster readTileRaster​(int imageIndex, int tileX, int tileY) throws IOException
    Returns a new `Raster` object containing the raw pixel data from the tile, without any color conversion applied. The application must determine how to interpret the pixel data by other means.

    If `canReadRaster()` returns `false`, this method throws an `UnsupportedOperationException`.

    The default implementation checks if reading `Raster`s is supported, and if so calls `readRaster(imageIndex, null)` if `tileX` and `tileY` are 0, or throws an `IllegalArgumentException` otherwise.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `tileX` - the column index (starting with 0) of the tile to be retrieved.
      `tileY` - the row index (starting with 0) of the tile to be retrieved.
    Returns:
      the tile as a `Raster`.
    Throws:
      `UnsupportedOperationException` - if this plug-in does not support reading raw `Raster`s.
      `IllegalArgumentException` - if the tile indices are out of bounds.
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if `imageIndex` is out of bounds.
      `IOException` - if an error occurs during reading.
    See Also:
      `readTile(int, int, int)`, `readRaster(int, javax.imageio.ImageReadParam)`, `Raster`

  - ### readAsRenderedImage

    public RenderedImage readAsRenderedImage​(int imageIndex, ImageReadParam param) throws IOException
    Returns a `RenderedImage` object that contains the contents of the image indexed by `imageIndex`. By default, the returned image is simply the `BufferedImage` returned by `read(imageIndex, param)`.

    The semantics of this method may differ from those of the other `read` methods in several ways. First, any destination image and/or image type set in the `ImageReadParam` may be ignored. Second, the usual listener calls are not guaranteed to be made, or to be meaningful if they are. This is because the returned image may not be fully populated with pixel data at the time it is returned, or indeed at any time.

    If the supplied `ImageReadParam` contains optional setting values not supported by this reader (e.g. source render size or any format-specific settings), they will be ignored.

    The default implementation just calls `read(imageIndex, param)`.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `param` - an `ImageReadParam` used to control the reading process, or `null`.
    Returns:
      a `RenderedImage` object providing a view of the image.
    Throws:
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if the supplied index is out of bounds.
      `IllegalArgumentException` - if the set of source and destination bands specified by `param.getSourceBands` and `param.getDestinationBands` differ in length or include indices that are out of bounds.
      `IllegalArgumentException` - if the resulting image would have a width or height less than 1.
      `IOException` - if an error occurs during reading.

  - ### readerSupportsThumbnails

    public boolean readerSupportsThumbnails()
    Returns `true` if the image format understood by this reader supports thumbnail preview images associated with it. The default implementation returns `false`.

    If this method returns `false`, `hasThumbnails` and `getNumThumbnails` will return `false` and `0`, respectively, and `readThumbnail` will throw an `UnsupportedOperationException`, regardless of their arguments.

    A reader that does not support thumbnails need not implement any of the thumbnail-related methods.

    Returns:
      `true` if thumbnails are supported.

  - ### hasThumbnails

    public boolean hasThumbnails​(int imageIndex) throws IOException
    Returns `true` if the given image has thumbnail preview images associated with it. If the format does not support thumbnails (`readerSupportsThumbnails` returns `false`), `false` will be returned regardless of whether an input source has been set or whether `imageIndex` is in bounds.

    The default implementation returns `true` if `getNumThumbnails` returns a value greater than 0.

    Parameters:
      `imageIndex` - the index of the image being queried.
    Returns:
      `true` if the given image has thumbnails.
    Throws:
      `IllegalStateException` - if the reader supports thumbnails but the input source has not been set.
      `IndexOutOfBoundsException` - if the reader supports thumbnails but `imageIndex` is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getNumThumbnails

    public int getNumThumbnails​(int imageIndex) throws IOException
    Returns the number of thumbnail preview images associated with the given image. If the format does not support thumbnails, (`readerSupportsThumbnails` returns `false`), `0` will be returned regardless of whether an input source has been set or whether `imageIndex` is in bounds.

    The default implementation returns 0 without checking its argument.

    Parameters:
      `imageIndex` - the index of the image being queried.
    Returns:
      the number of thumbnails associated with the given image.
    Throws:
      `IllegalStateException` - if the reader supports thumbnails but the input source has not been set.
      `IndexOutOfBoundsException` - if the reader supports thumbnails but `imageIndex` is out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getThumbnailWidth

    public int getThumbnailWidth​(int imageIndex, int thumbnailIndex) throws IOException
    Returns the width of the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex`.

    If the reader does not support thumbnails, (`readerSupportsThumbnails` returns `false`), an `UnsupportedOperationException` will be thrown.

    The default implementation simply returns `readThumbnail(imageindex, thumbnailIndex).getWidth()`. Subclasses should therefore override this method if possible in order to avoid forcing the thumbnail to be read.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `thumbnailIndex` - the index of the thumbnail to be retrieved.
    Returns:
      the width of the desired thumbnail as an `int`.
    Throws:
      `UnsupportedOperationException` - if thumbnails are not supported.
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if either of the supplied indices are out of bounds.
      `IOException` - if an error occurs during reading.

  - ### getThumbnailHeight

    public int getThumbnailHeight​(int imageIndex, int thumbnailIndex) throws IOException
    Returns the height of the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex`.

    If the reader does not support thumbnails, (`readerSupportsThumbnails` returns `false`), an `UnsupportedOperationException` will be thrown.

    The default implementation simply returns `readThumbnail(imageindex, thumbnailIndex).getHeight()`. Subclasses should therefore override this method if possible in order to avoid forcing the thumbnail to be read.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `thumbnailIndex` - the index of the thumbnail to be retrieved.
    Returns:
      the height of the desired thumbnail as an `int`.
    Throws:
      `UnsupportedOperationException` - if thumbnails are not supported.
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if either of the supplied indices are out of bounds.
      `IOException` - if an error occurs during reading.

  - ### readThumbnail

    public BufferedImage readThumbnail​(int imageIndex, int thumbnailIndex) throws IOException
    Returns the thumbnail preview image indexed by `thumbnailIndex`, associated with the image indexed by `ImageIndex` as a `BufferedImage`.

    Any registered `IIOReadProgressListener` objects will be notified by calling their `thumbnailStarted`, `thumbnailProgress`, and `thumbnailComplete` methods.

    If the reader does not support thumbnails, (`readerSupportsThumbnails` returns `false`), an `UnsupportedOperationException` will be thrown regardless of whether an input source has been set or whether the indices are in bounds.

    The default implementation throws an `UnsupportedOperationException`.

    Parameters:
      `imageIndex` - the index of the image to be retrieved.
      `thumbnailIndex` - the index of the thumbnail to be retrieved.
    Returns:
      the desired thumbnail as a `BufferedImage`.
    Throws:
      `UnsupportedOperationException` - if thumbnails are not supported.
      `IllegalStateException` - if the input source has not been set.
      `IndexOutOfBoundsException` - if either of the supplied indices are out of bounds.
      `IOException` - if an error occurs during reading.

  - ### abort

    public void abort()
    Requests that any current read operation be aborted. The contents of the image following the abort will be undefined.

    Readers should call `clearAbortRequest` at the beginning of each read operation, and poll the value of `abortRequested` regularly during the read.

  - ### abortRequested

    protected boolean abortRequested()
    Returns `true` if a request to abort the current read operation has been made since the reader was instantiated or `clearAbortRequest` was called.
    Returns:
      `true` if the current read operation should be aborted.
    See Also:
      `abort()`, `clearAbortRequest()`

  - ### clearAbortRequest

    protected void clearAbortRequest()
    Clears any previous abort request. After this method has been called, `abortRequested` will return `false`.
    See Also:
      `abort()`, `abortRequested()`

  - ### addIIOReadWarningListener

    public void addIIOReadWarningListener​(IIOReadWarningListener listener)
    Adds an `IIOReadWarningListener` to the list of registered warning listeners. If `listener` is `null`, no exception will be thrown and no action will be taken. Messages sent to the given listener will be localized, if possible, to match the current `Locale`. If no `Locale` has been set, warning messages may be localized as the reader sees fit.
    Parameters:
      `listener` - an `IIOReadWarningListener` to be registered.
    See Also:
      `removeIIOReadWarningListener(javax.imageio.event.IIOReadWarningListener)`

  - ### removeIIOReadWarningListener

    public void removeIIOReadWarningListener​(IIOReadWarningListener listener)
    Removes an `IIOReadWarningListener` from the list of registered error listeners. If the listener was not previously registered, or if `listener` is `null`, no exception will be thrown and no action will be taken.
    Parameters:
      `listener` - an IIOReadWarningListener to be unregistered.
    See Also:
      `addIIOReadWarningListener(javax.imageio.event.IIOReadWarningListener)`

  - ### removeAllIIOReadWarningListeners

    public void removeAllIIOReadWarningListeners()
    Removes all currently registered `IIOReadWarningListener` objects.

    The default implementation sets the `warningListeners` and `warningLocales` instance variables to `null`.

  - ### addIIOReadProgressListener

    public void addIIOReadProgressListener​(IIOReadProgressListener listener)
    Adds an `IIOReadProgressListener` to the list of registered progress listeners. If `listener` is `null`, no exception will be thrown and no action will be taken.
    Parameters:
      `listener` - an IIOReadProgressListener to be registered.
    See Also:
      `removeIIOReadProgressListener(javax.imageio.event.IIOReadProgressListener)`

  - ### removeIIOReadProgressListener

    public void removeIIOReadProgressListener​(IIOReadProgressListener listener)
    Removes an `IIOReadProgressListener` from the list of registered progress listeners. If the listener was not previously registered, or if `listener` is `null`, no exception will be thrown and no action will be taken.
    Parameters:
      `listener` - an IIOReadProgressListener to be unregistered.
    See Also:
      `addIIOReadProgressListener(javax.imageio.event.IIOReadProgressListener)`

  - ### removeAllIIOReadProgressListeners

    public void removeAllIIOReadProgressListeners()
    Removes all currently registered `IIOReadProgressListener` objects.

    The default implementation sets the `progressListeners` instance variable to `null`.

  - ### addIIOReadUpdateListener

    public void addIIOReadUpdateListener​(IIOReadUpdateListener listener)
    Adds an `IIOReadUpdateListener` to the list of registered update listeners. If `listener` is `null`, no exception will be thrown and no action will be taken. The listener will receive notification of pixel updates as images and thumbnails are decoded, including the starts and ends of progressive passes.

    If no update listeners are present, the reader may choose to perform fewer updates to the pixels of the destination images and/or thumbnails, which may result in more efficient decoding.

    For example, in progressive JPEG decoding each pass contains updates to a set of coefficients, which would have to be transformed into pixel values and converted to an RGB color space for each pass if listeners are present. If no listeners are present, the coefficients may simply be accumulated and the final results transformed and color converted one time only.

    The final results of decoding will be the same whether or not intermediate updates are performed. Thus if only the final image is desired it may be preferable not to register any `IIOReadUpdateListener`s. In general, progressive updating is most effective when fetching images over a network connection that is very slow compared to local CPU processing; over a fast connection, progressive updates may actually slow down the presentation of the image.

    Parameters:
      `listener` - an IIOReadUpdateListener to be registered.
    See Also:
      `removeIIOReadUpdateListener(javax.imageio.event.IIOReadUpdateListener)`

  - ### removeIIOReadUpdateListener

    public void removeIIOReadUpdateListener​(IIOReadUpdateListener listener)
    Removes an `IIOReadUpdateListener` from the list of registered update listeners. If the listener was not previously registered, or if `listener` is `null`, no exception will be thrown and no action will be taken.
    Parameters:
      `listener` - an IIOReadUpdateListener to be unregistered.
    See Also:
      `addIIOReadUpdateListener(javax.imageio.event.IIOReadUpdateListener)`

  - ### removeAllIIOReadUpdateListeners

    public void removeAllIIOReadUpdateListeners()
    Removes all currently registered `IIOReadUpdateListener` objects.

    The default implementation sets the `updateListeners` instance variable to `null`.

  - ### processSequenceStarted

    protected void processSequenceStarted​(int minIndex)
    Broadcasts the start of an sequence of image reads to all registered `IIOReadProgressListener`s by calling their `sequenceStarted` method. Subclasses may use this method as a convenience.
    Parameters:
      `minIndex` - the lowest index being read.

  - ### processSequenceComplete

    protected void processSequenceComplete()
    Broadcasts the completion of an sequence of image reads to all registered `IIOReadProgressListener`s by calling their `sequenceComplete` method. Subclasses may use this method as a convenience.

  - ### processImageStarted

    protected void processImageStarted​(int imageIndex)
    Broadcasts the start of an image read to all registered `IIOReadProgressListener`s by calling their `imageStarted` method. Subclasses may use this method as a convenience.
    Parameters:
      `imageIndex` - the index of the image about to be read.

  - ### processImageProgress

    protected void processImageProgress​(float percentageDone)
    Broadcasts the current percentage of image completion to all registered `IIOReadProgressListener`s by calling their `imageProgress` method. Subclasses may use this method as a convenience.
    Parameters:
      `percentageDone` - the current percentage of completion, as a `float`.

  - ### processImageComplete

    protected void processImageComplete()
    Broadcasts the completion of an image read to all registered `IIOReadProgressListener`s by calling their `imageComplete` method. Subclasses may use this method as a convenience.

  - ### processThumbnailStarted

    protected void processThumbnailStarted​(int imageIndex, int thumbnailIndex)
    Broadcasts the start of a thumbnail read to all registered `IIOReadProgressListener`s by calling their `thumbnailStarted` method. Subclasses may use this method as a convenience.
    Parameters:
      `imageIndex` - the index of the image associated with the thumbnail.
      `thumbnailIndex` - the index of the thumbnail.

  - ### processThumbnailProgress

    protected void processThumbnailProgress​(float percentageDone)
    Broadcasts the current percentage of thumbnail completion to all registered `IIOReadProgressListener`s by calling their `thumbnailProgress` method. Subclasses may use this method as a convenience.
    Parameters:
      `percentageDone` - the current percentage of completion, as a `float`.

  - ### processThumbnailComplete

    protected void processThumbnailComplete()
    Broadcasts the completion of a thumbnail read to all registered `IIOReadProgressListener`s by calling their `thumbnailComplete` method. Subclasses may use this method as a convenience.

  - ### processReadAborted

    protected void processReadAborted()
    Broadcasts that the read has been aborted to all registered `IIOReadProgressListener`s by calling their `readAborted` method. Subclasses may use this method as a convenience.

  - ### processPassStarted

    protected void processPassStarted​(BufferedImage theImage, int pass, int minPass, int maxPass, int minX, int minY, int periodX, int periodY, int[] bands)
    Broadcasts the beginning of a progressive pass to all registered `IIOReadUpdateListener`s by calling their `passStarted` method. Subclasses may use this method as a convenience.
    Parameters:
      `theImage` - the `BufferedImage` being updated.
      `pass` - the index of the current pass, starting with 0.
      `minPass` - the index of the first pass that will be decoded.
      `maxPass` - the index of the last pass that will be decoded.
      `minX` - the X coordinate of the upper-left pixel included in the pass.
      `minY` - the X coordinate of the upper-left pixel included in the pass.
      `periodX` - the horizontal separation between pixels.
      `periodY` - the vertical separation between pixels.
      `bands` - an array of `int`s indicating the set of affected bands of the destination.

  - ### processImageUpdate

    protected void processImageUpdate​(BufferedImage theImage, int minX, int minY, int width, int height, int periodX, int periodY, int[] bands)
    Broadcasts the update of a set of samples to all registered `IIOReadUpdateListener`s by calling their `imageUpdate` method. Subclasses may use this method as a convenience.
    Parameters:
      `theImage` - the `BufferedImage` being updated.
      `minX` - the X coordinate of the upper-left pixel included in the pass.
      `minY` - the X coordinate of the upper-left pixel included in the pass.
      `width` - the total width of the area being updated, including pixels being skipped if `periodX > 1`.
      `height` - the total height of the area being updated, including pixels being skipped if `periodY > 1`.
      `periodX` - the horizontal separation between pixels.
      `periodY` - the vertical separation between pixels.
      `bands` - an array of `int`s indicating the set of affected bands of the destination.

  - ### processPassComplete

    protected void processPassComplete​(BufferedImage theImage)
    Broadcasts the end of a progressive pass to all registered `IIOReadUpdateListener`s by calling their `passComplete` method. Subclasses may use this method as a convenience.
    Parameters:
      `theImage` - the `BufferedImage` being updated.

  - ### processThumbnailPassStarted

    protected void processThumbnailPassStarted​(BufferedImage theThumbnail, int pass, int minPass, int maxPass, int minX, int minY, int periodX, int periodY, int[] bands)
    Broadcasts the beginning of a thumbnail progressive pass to all registered `IIOReadUpdateListener`s by calling their `thumbnailPassStarted` method. Subclasses may use this method as a convenience.
    Parameters:
      `theThumbnail` - the `BufferedImage` thumbnail being updated.
      `pass` - the index of the current pass, starting with 0.
      `minPass` - the index of the first pass that will be decoded.
      `maxPass` - the index of the last pass that will be decoded.
      `minX` - the X coordinate of the upper-left pixel included in the pass.
      `minY` - the X coordinate of the upper-left pixel included in the pass.
      `periodX` - the horizontal separation between pixels.
      `periodY` - the vertical separation between pixels.
      `bands` - an array of `int`s indicating the set of affected bands of the destination.

  - ### processThumbnailUpdate

    protected void processThumbnailUpdate​(BufferedImage theThumbnail, int minX, int minY, int width, int height, int periodX, int periodY, int[] bands)
    Broadcasts the update of a set of samples in a thumbnail image to all registered `IIOReadUpdateListener`s by calling their `thumbnailUpdate` method. Subclasses may use this method as a convenience.
    Parameters:
      `theThumbnail` - the `BufferedImage` thumbnail being updated.
      `minX` - the X coordinate of the upper-left pixel included in the pass.
      `minY` - the X coordinate of the upper-left pixel included in the pass.
      `width` - the total width of the area being updated, including pixels being skipped if `periodX > 1`.
      `height` - the total height of the area being updated, including pixels being skipped if `periodY > 1`.
      `periodX` - the horizontal separation between pixels.
      `periodY` - the vertical separation between pixels.
      `bands` - an array of `int`s indicating the set of affected bands of the destination.

  - ### processThumbnailPassComplete

    protected void processThumbnailPassComplete​(BufferedImage theThumbnail)
    Broadcasts the end of a thumbnail progressive pass to all registered `IIOReadUpdateListener`s by calling their `thumbnailPassComplete` method. Subclasses may use this method as a convenience.
    Parameters:
      `theThumbnail` - the `BufferedImage` thumbnail being updated.

  - ### processWarningOccurred

    protected void processWarningOccurred​(String warning)
    Broadcasts a warning message to all registered `IIOReadWarningListener`s by calling their `warningOccurred` method. Subclasses may use this method as a convenience.
    Parameters:
      `warning` - the warning message to send.
    Throws:
      `IllegalArgumentException` - if `warning` is `null`.

  - ### processWarningOccurred

    protected void processWarningOccurred​(String baseName, String keyword)
    Broadcasts a localized warning message to all registered `IIOReadWarningListener`s by calling their `warningOccurred` method with a string taken from a `ResourceBundle`. Subclasses may use this method as a convenience.
    Parameters:
      `baseName` - the base name of a set of `ResourceBundle`s containing localized warning messages.
      `keyword` - the keyword used to index the warning message within the set of `ResourceBundle`s.
    Throws:
      `IllegalArgumentException` - if `baseName` is `null`.
      `IllegalArgumentException` - if `keyword` is `null`.
      `IllegalArgumentException` - if no appropriate `ResourceBundle` may be located.
      `IllegalArgumentException` - if the named resource is not found in the located `ResourceBundle`.
      `IllegalArgumentException` - if the object retrieved from the `ResourceBundle` is not a `String`.

  - ### reset

    public void reset()
    Restores the `ImageReader` to its initial state.

    The default implementation calls `setInput(null, false)`, `setLocale(null)`, `removeAllIIOReadUpdateListeners()`, `removeAllIIOReadWarningListeners()`, `removeAllIIOReadProgressListeners()`, and `clearAbortRequest`.

  - ### dispose

    public void dispose()
    Allows any resources held by this object to be released. The result of calling any other method (other than `finalize`) subsequent to a call to this method is undefined.

    It is important for applications to call this method when they know they will no longer be using this `ImageReader`. Otherwise, the reader may continue to hold on to resources indefinitely.

    The default implementation of this method in the superclass does nothing. Subclass implementations should ensure that all resources, especially native resources, are released.

  - ### getSourceRegion

    protected static Rectangle getSourceRegion​(ImageReadParam param, int srcWidth, int srcHeight)
    A utility method that may be used by readers to compute the region of the source image that should be read, taking into account any source region and subsampling offset settings in the supplied `ImageReadParam`. The actual subsampling factors, destination size, and destination offset are not taken into consideration, thus further clipping must take place. The `computeRegions` method performs all necessary clipping.
    Parameters:
      `param` - the `ImageReadParam` being used, or `null`.
      `srcWidth` - the width of the source image.
      `srcHeight` - the height of the source image.
    Returns:
      the source region as a `Rectangle`.

  - ### computeRegions

    protected static void computeRegions​(ImageReadParam param, int srcWidth, int srcHeight, BufferedImage image, Rectangle srcRegion, Rectangle destRegion)
    Computes the source region of interest and the destination region of interest, taking the width and height of the source image, an optional destination image, and an optional `ImageReadParam` into account. The source region begins with the entire source image. Then that is clipped to the source region specified in the `ImageReadParam`, if one is specified.

    If either of the destination offsets are negative, the source region is clipped so that its top left will coincide with the top left of the destination image, taking subsampling into account. Then the result is clipped to the destination image on the right and bottom, if one is specified, taking subsampling and destination offsets into account.

    Similarly, the destination region begins with the source image, is translated to the destination offset given in the `ImageReadParam` if there is one, and finally is clipped to the destination image, if there is one.

    If either the source or destination regions end up having a width or height of 0, an `IllegalArgumentException` is thrown.

    The `getSourceRegion>` method may be used if only source clipping is desired.

    Parameters:
      `param` - an `ImageReadParam`, or `null`.
      `srcWidth` - the width of the source image.
      `srcHeight` - the height of the source image.
      `image` - a `BufferedImage` that will be the destination image, or `null`.
      `srcRegion` - a `Rectangle` that will be filled with the source region of interest.
      `destRegion` - a `Rectangle` that will be filled with the destination region of interest.
    Throws:
      `IllegalArgumentException` - if `srcRegion` is `null`.
      `IllegalArgumentException` - if `dstRegion` is `null`.
      `IllegalArgumentException` - if the resulting source or destination region is empty.

  - ### checkReadParamBandSettings

    protected static void checkReadParamBandSettings​(ImageReadParam param, int numSrcBands, int numDstBands)
    A utility method that may be used by readers to test the validity of the source and destination band settings of an `ImageReadParam`. This method may be called as soon as the reader knows both the number of bands of the source image as it exists in the input stream, and the number of bands of the destination image that being written.

    The method retrieves the source and destination band setting arrays from param using the `getSourceBands` and `getDestinationBands` methods (or considers them to be `null` if `param` is `null`). If the source band setting array is `null`, it is considered to be equal to the array `{ 0, 1, ..., numSrcBands - 1 }`, and similarly for the destination band setting array.

    The method then tests that both arrays are equal in length, and that neither array contains a value larger than the largest available band index.

    Any failure results in an `IllegalArgumentException` being thrown; success results in the method returning silently.

    Parameters:
      `param` - the `ImageReadParam` being used to read the image.
      `numSrcBands` - the number of bands of the image as it exists int the input source.
      `numDstBands` - the number of bands in the destination image being written.
    Throws:
      `IllegalArgumentException` - if `param` contains an invalid specification of a source and/or destination band subset.

  - ### getDestination

    protected static BufferedImage getDestination​(ImageReadParam param, Iterator<ImageTypeSpecifier> imageTypes, int width, int height) throws IIOException
    Returns the `BufferedImage` to which decoded pixel data should be written. The image is determined by inspecting the supplied `ImageReadParam` if it is non-`null`; if its `getDestination` method returns a non-`null` value, that image is simply returned. Otherwise, `param.getDestinationType` method is called to determine if a particular image type has been specified. If so, the returned `ImageTypeSpecifier` is used after checking that it is equal to one of those included in `imageTypes`.

    If `param` is `null` or the above steps have not yielded an image or an `ImageTypeSpecifier`, the first value obtained from the `imageTypes` parameter is used. Typically, the caller will set `imageTypes` to the value of `getImageTypes(imageIndex)`.

    Next, the dimensions of the image are determined by a call to `computeRegions`. The actual width and height of the image being decoded are passed in as the `width` and `height` parameters.

    Parameters:
      `param` - an `ImageReadParam` to be used to get the destination image or image type, or `null`.
      `imageTypes` - an `Iterator` of `ImageTypeSpecifier`s indicating the legal image types, with the default first.
      `width` - the true width of the image or tile being decoded.
      `height` - the true width of the image or tile being decoded.
    Returns:
      the `BufferedImage` to which decoded pixel data should be written.
    Throws:
      `IIOException` - if the `ImageTypeSpecifier` specified by `param` does not match any of the legal ones from `imageTypes`.
      `IllegalArgumentException` - if `imageTypes` is `null` or empty, or if an object not of type `ImageTypeSpecifier` is retrieved from it.
      `IllegalArgumentException` - if the resulting image would have a width or height less than 1.
      `IllegalArgumentException` - if the product of `width` and `height` is greater than `Integer.MAX_VALUE`.