Class ImageToImageOperation

  • Direct Known Subclasses:
    ArbitraryPaletteQuantizer, AreaFilterOperation, ClusteredDotDither, ConvolutionKernelFilter, Crop, ErrorDiffusionDithering, Flip, HueSaturationValue, Invert, LookupTableOperation, MedianCutContourRemoval, MedianCutQuantizer, Mirror, OctreeColorQuantizer, OrderedDither, PopularityQuantizer, PromotionGray16, PromotionGray8, PromotionPaletted8, PromotionRGB24, PromotionRGB48, ReduceRGB, ReduceShadesOfGray, ReduceToBilevelThreshold, Resample, RGBToGrayConversion, Rotate180, Rotate90Left, Rotate90Right, ScaleReplication, Shear, UniformPaletteQuantizer

    public abstract class ImageToImageOperation
    extends Operation
    An operation that acesses an input image and produces data for an output image. This abstract class only provides methods to get and set those images.

    Normally, an operation creates the output image itself. However, an output image can be specified by the user with setOutputImage(net.sourceforge.jiu.data.PixelImage). This could be done when existing image objects are to be reused.

    An operation extending ImageToImageOperation must check if (1) a user-defined output image is available and (2) whether that image matches the required criteria. The criteria depend on the operation - example: for an operation that rotates an image by 180 degrees, an output image must have the same resolution as the input image and be of the same type.

    If an output image is not available (case #1), the operation must create the matching output image itself. It should know best what is required. Very generic methods (like rotation of images by 90 degrees) must know relatively little about the image. They can make use of PixelImage.createCompatibleImage(int, int) and provide width and height. That way, the operation works for all kinds of images, like BilevelImage, Paletted8Image, Gray8Image, RGB24Image etc.

    If a user-provided image does not match the required criteria, an appropriate exception (most of the time WrongParameterException will do) with a descriptive error message must be thrown. In the example of the 90-degree rotation, the width of the output image must be equal to the height of the input image and vice versa. The types of input and output must be equal.

    However, there are limits to the checks on user-provided output images. As an example, a generic test could not check if a paletted output image has the same palette as the input counterpart because it treats all images based on IntegerImage the same.

    When performing an image-to-image-operation, the input image can possibly be used as the output image. This can be done

    • if input and output are of the same type and resolution and
    • if the operation needs only one input pixel to compute the output pixel at any given position.

    Mirroring the image horizontally is an example of an operation that can be implemented that way - the operation starts at the top left and at the bottom right pixel, swaps them and proceeds one pixel to the right of the top left pixel (and one to the left of the bottom right pixel).

    Since:
    0.6.0
    Author:
    Marco Schmidt
    • Field Detail

      • canInAndOutBeEqual

        private boolean canInAndOutBeEqual
    • Constructor Detail

      • ImageToImageOperation

        public ImageToImageOperation​(PixelImage in,
                                     PixelImage out)
        Creates an object of this class and sets input image and output image to the argument values.
      • ImageToImageOperation

        public ImageToImageOperation​(PixelImage in)
        Creates an object of this class and sets the input image to the argument value, output image to null.
      • ImageToImageOperation

        public ImageToImageOperation()
        Creates an object of this class and sets both input image and output image to null.
    • Method Detail

      • canInputAndOutputBeEqual

        public boolean canInputAndOutputBeEqual()
        Returns if input and output image are allowed to be the same object.
        See Also:
        setCanInputAndOutputBeEqual(boolean)
      • ensureImagesHaveSameResolution

        public void ensureImagesHaveSameResolution()
                                            throws WrongParameterException
        If both an input and an output image have been specified (both non-null), this method compares their width and height properties and throws an exception if the two images do not have the same resolution.
        Throws:
        WrongParameterException - if input and output images exist and their resolutions differ
      • ensureOutputImageResolution

        public void ensureOutputImageResolution​(int width,
                                                int height)
                                         throws WrongParameterException
        If an output image has been specified this method will compare its resolution with the argument resolution and throw an exception if the resolutions differ. If no output image has been specified nothing happens.
        Parameters:
        width - the horizontal pixel resolution that the output image must have
        height - the vertical pixel resolution that the output image must have
        Throws:
        WrongParameterException - if the resolutions differ
      • getInputImage

        public PixelImage getInputImage()
        Returns the input image stored in this object.
        Returns:
        input image, possibly null
      • getOutputImage

        public PixelImage getOutputImage()
        Returns the output image stored in this object.
        Returns:
        output image, possibly null
      • setCanInputAndOutputBeEqual

        public void setCanInputAndOutputBeEqual​(boolean newValue)
        Specify if input and output image are allowed to be the same object.
        See Also:
        canInputAndOutputBeEqual()
      • setInputImage

        public void setInputImage​(PixelImage in)
        Sets the input image stored in this object to the argument. Argument can be null.
        Parameters:
        in - the new input image of this object
      • setOutputImage

        public void setOutputImage​(PixelImage out)
        Sets the output image stored in this object to the argument. Argument can be null.
        Parameters:
        out - the new output image of this object