# Class LookupOp

java.lang.Object
java.awt.image.LookupOp

All Implemented Interfaces:
  `BufferedImageOp, RasterOp`

public class LookupOp extends Object implements BufferedImageOp, RasterOp
This class implements a lookup operation from the source to the destination. The LookupTable object may contain a single array or multiple arrays, subject to the restrictions below.

For Rasters, the lookup operates on bands. The number of lookup arrays may be one, in which case the same array is applied to all bands, or it must equal the number of Source Raster bands.

For BufferedImages, the lookup operates on color and alpha components. The number of lookup arrays may be one, in which case the same array is applied to all color (but not alpha) components. Otherwise, the number of lookup arrays may equal the number of Source color components, in which case no lookup of the alpha component (if present) is performed. If neither of these cases apply, the number of lookup arrays must equal the number of Source color components plus alpha components, in which case lookup is performed for all color and alpha components. This allows non-uniform rescaling of multi-band BufferedImages.

BufferedImage sources with premultiplied alpha data are treated in the same manner as non-premultiplied images for purposes of the lookup. That is, the lookup is done per band on the raw data of the BufferedImage source without regard to whether the data is premultiplied. If a color conversion is required to the destination ColorModel, the premultiplied state of both source and destination will be taken into account for this step.

Images with an IndexColorModel cannot be used.

If a RenderingHints object is specified in the constructor, the color rendering hint and the dithering hint may be used when color conversion is required.

This class allows the Source to be the same as the Destination.

See Also:
  - `LookupTable`
  - `RenderingHints.KEY_COLOR_RENDERING`
  - `RenderingHints.KEY_DITHERING`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `LookupOp(LookupTable lookup, RenderingHints hints)`
  Constructs a `LookupOp` object given the lookup table and a `RenderingHints` object, which might be `null`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `BufferedImage`
  `createCompatibleDestImage(BufferedImage src, ColorModel destCM)`
  Creates a zeroed destination image with the correct size and number of bands.
  `WritableRaster`
  `createCompatibleDestRaster(Raster src)`
  Creates a zeroed-destination `Raster` with the correct size and number of bands, given this source.
  `final BufferedImage`
  `filter(BufferedImage src, BufferedImage dst)`
  Performs a lookup operation on a `BufferedImage`.
  `final WritableRaster`
  `filter(Raster src, WritableRaster dst)`
  Performs a lookup operation on a `Raster`.
  `final Rectangle2D`
  `getBounds2D(BufferedImage src)`
  Returns the bounding box of the filtered destination image.
  `final Rectangle2D`
  `getBounds2D(Raster src)`
  Returns the bounding box of the filtered destination Raster.
  `final Point2D`
  `getPoint2D(Point2D srcPt, Point2D dstPt)`
  Returns the location of the destination point given a point in the source.
  `final RenderingHints`
  `getRenderingHints()`
  Returns the rendering hints for this op.
  `final LookupTable`
  `getTable()`
  Returns the `LookupTable`.

  ### Methods declared in class Object

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

- ## Constructor Details

  - ### LookupOp

    public LookupOp(LookupTable lookup, RenderingHints hints)
    Constructs a `LookupOp` object given the lookup table and a `RenderingHints` object, which might be `null`.
    Parameters:
      `lookup` - the specified `LookupTable`
      `hints` - the specified `RenderingHints`, or `null`

- ## Method Details

  - ### getTable

    public final LookupTable getTable()
    Returns the `LookupTable`.
    Returns:
      the `LookupTable` of this `LookupOp`.

  - ### filter

    public final BufferedImage filter(BufferedImage src, BufferedImage dst)
    Performs a lookup operation on a `BufferedImage`. If the color model in the source image is not the same as that in the destination image, the pixels will be converted in the destination. If the destination image is `null`, a `BufferedImage` will be created with an appropriate `ColorModel`. An `IllegalArgumentException` might be thrown if the number of arrays in the `LookupTable` does not meet the restrictions stated in the class comment above, or if the source image has an `IndexColorModel`.
    Specified by:
      `filter` in interface `BufferedImageOp`
    Parameters:
      `src` - the `BufferedImage` to be filtered
      `dst` - the `BufferedImage` in which to store the results of the filter operation
    Returns:
      the filtered `BufferedImage`.
    Throws:
      `IllegalArgumentException` - if the number of arrays in the `LookupTable` does not meet the restrictions described in the class comments, or if the source image has an `IndexColorModel`.

  - ### filter

    public final WritableRaster filter(Raster src, WritableRaster dst)
    Performs a lookup operation on a `Raster`. If the destination `Raster` is `null`, a new `Raster` will be created. The `IllegalArgumentException` might be thrown if the source `Raster` and the destination `Raster` do not have the same number of bands or if the number of arrays in the `LookupTable` does not meet the restrictions stated in the class comment above.
    Specified by:
      `filter` in interface `RasterOp`
    Parameters:
      `src` - the source `Raster` to filter
      `dst` - the destination `WritableRaster` for the filtered `src`
    Returns:
      the filtered `WritableRaster`.
    Throws:
      `IllegalArgumentException` - if the source and destinations rasters do not have the same number of bands, or the number of arrays in the `LookupTable` does not meet the restrictions described in the class comments.

  - ### getBounds2D

    public final Rectangle2D getBounds2D(BufferedImage src)
    Returns the bounding box of the filtered destination image. Since this is not a geometric operation, the bounding box does not change.
    Specified by:
      `getBounds2D` in interface `BufferedImageOp`
    Parameters:
      `src` - the `BufferedImage` to be filtered
    Returns:
      the bounds of the filtered definition image.

  - ### getBounds2D

    public final Rectangle2D getBounds2D(Raster src)
    Returns the bounding box of the filtered destination Raster. Since this is not a geometric operation, the bounding box does not change.
    Specified by:
      `getBounds2D` in interface `RasterOp`
    Parameters:
      `src` - the `Raster` to be filtered
    Returns:
      the bounds of the filtered definition `Raster`.

  - ### createCompatibleDestImage

    public BufferedImage createCompatibleDestImage(BufferedImage src, ColorModel destCM)
    Creates a zeroed destination image with the correct size and number of bands. If destCM is `null`, an appropriate `ColorModel` will be used.
    Specified by:
      `createCompatibleDestImage` in interface `BufferedImageOp`
    Parameters:
      `src` - Source image for the filter operation.
      `destCM` - the destination's `ColorModel`, which can be `null`.
    Returns:
      a filtered destination `BufferedImage`.

  - ### createCompatibleDestRaster

    public WritableRaster createCompatibleDestRaster(Raster src)
    Creates a zeroed-destination `Raster` with the correct size and number of bands, given this source.
    Specified by:
      `createCompatibleDestRaster` in interface `RasterOp`
    Parameters:
      `src` - the `Raster` to be transformed
    Returns:
      the zeroed-destination `Raster`.

  - ### getPoint2D

    public final Point2D getPoint2D(Point2D srcPt, Point2D dstPt)
    Returns the location of the destination point given a point in the source. If `dstPt` is not `null`, it will be used to hold the return value. Since this is not a geometric operation, the `srcPt` will equal the `dstPt`.
    Specified by:
      `getPoint2D` in interface `BufferedImageOp`
    Specified by:
      `getPoint2D` in interface `RasterOp`
    Parameters:
      `srcPt` - a `Point2D` that represents a point in the source image
      `dstPt` - a `Point2D` that represents the location in the destination
    Returns:
      the `Point2D` in the destination that corresponds to the specified point in the source.

  - ### getRenderingHints

    public final RenderingHints getRenderingHints()
    Returns the rendering hints for this op.
    Specified by:
      `getRenderingHints` in interface `BufferedImageOp`
    Specified by:
      `getRenderingHints` in interface `RasterOp`
    Returns:
      the `RenderingHints` object associated with this op.