Class: java.awt.image.AreaAveragingScaleFilter

An ImageFilter class for scaling images using a simple area averaging algorithm that produces smoother results than the nearest neighbor algorithm.

This class extends the basic ImageFilter Class to scale an existing image and provide a source for a new image containing the resampled image. The pixels in the source image are blended to produce pixels for an image of the specified size. The blending process is analogous to scaling up the source image to a multiple of the destination size using pixel replication and then scaling it back down to the destination size by simply averaging all the pixels in the supersized image that fall within a given pixel of the destination image. If the data from the source is not delivered in TopDownLeftRight order then the filter will back off to a simple pixel replication behavior and utilize the requestTopDownLeftRightResend() method to refilter the pixels in a better way at the end.

It is meant to be used in conjunction with a FilteredImageSource object to produce scaled versions of existing images. Due to implementation dependencies, there may be differences in pixel values of an image filtered on different platforms.

Authors:
@author Jim Graham
See:
@see java.awt.image.FilteredImageSource
@see java.awt.image.ReplicateScaleFilter
@see java.awt.image.ImageFilter

Inheritance

Superclass tree: Implements:

Methods

  • AreaAveragingScaleFiltertop

    public AreaAveragingScaleFilter(int width, int height)
    Constructs an AreaAveragingScaleFilter that scales the pixels from its source Image as specified by the width and height parameters.
    Parameters:
    @param width the target width to scale the image
    @param height the target height to scale the image
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  • accumPixelstop

    private void accumPixels(int x, int y, int w, int h, ColorModel model, Object pixels, int off, int scansize)
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  • calcRowtop

    private int[] calcRow()
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  • makeAccumBufferstop

    private void makeAccumBuffers()
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  • setHintstop

    public void setHints(int hints)
    Detect if the data is being delivered with the necessary hints to allow the averaging algorithm to do its work.

    Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

    See:
    @see java.awt.image.ImageConsumer.setHints(int)
    Specified by:
    setHints from ImageConsumer
    Override hierarchy:
    setHints from ImageFilter
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  • setPixelstop

    public void setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize)
    Combine the components for the delivered byte pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete. If the correct hints were not specified in the setHints call then relay the work to our superclass which is capable of scaling pixels regardless of the delivery hints.

    Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

    Parameters:
    @param x the X coordinate of the upper-left corner of the area of pixels to be set
    @param y the Y coordinate of the upper-left corner of the area of pixels to be set
    @param w the width of the area of pixels
    @param h the height of the area of pixels
    @param model the specified ColorModel
    @param pixels the array of pixels
    @param off the offset into the pixels array
    @param scansize the distance from one row of pixels to the next in the pixels array
    See:
    @see java.awt.image.ReplicateScaleFilter
    Specified by:
    setPixels from ImageConsumer
    Override hierarchy:
    setPixels from ReplicateScaleFilter
    setPixels from ImageFilter
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  • setPixelstop

    public void setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize)
    Combine the components for the delivered int pixels into the accumulation arrays and send on any averaged data for rows of pixels that are complete. If the correct hints were not specified in the setHints call then relay the work to our superclass which is capable of scaling pixels regardless of the delivery hints.

    Note: This method is intended to be called by the ImageProducer of the Image whose pixels are being filtered. Developers using this class to filter pixels from an image should avoid calling this method directly since that operation could interfere with the filtering operation.

    Parameters:
    @param x the X coordinate of the upper-left corner of the area of pixels to be set
    @param y the Y coordinate of the upper-left corner of the area of pixels to be set
    @param w the width of the area of pixels
    @param h the height of the area of pixels
    @param model the specified ColorModel
    @param pixels the array of pixels
    @param off the offset into the pixels array
    @param scansize the distance from one row of pixels to the next in the pixels array
    See:
    @see java.awt.image.ReplicateScaleFilter
    Specified by:
    setPixels from ImageConsumer
    Override hierarchy:
    setPixels from ReplicateScaleFilter
    setPixels from ImageFilter
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Fields

  • alphas

    private float[] alphas

  • blues

    private float[] blues

  • greens

    private float[] greens

  • neededHints

    static final private int neededHints = 6

  • passthrough

    private boolean passthrough

  • reds

    private float[] reds

  • rgbmodel

    static final private ColorModel rgbmodel

  • savedy

    private int savedy

  • savedyrem

    private int savedyrem