Class ConvolutionKernelFilter


public class ConvolutionKernelFilter extends ImageToImageOperation
Applies a convolution kernel filter to an image.

Supported image types

Only image types that store intensity samples are supported. Right now, this only includes GrayIntegerImage and RGBIntegerImage.

Usage example

Standard approach (set up everything yourself):
 ConvolutionKernelFilter filter = new ConvolutionKernelFilter();
 filter.setKernel(ConvolutionKernelFilter.TYPE_SHARPEN);
 filter.setInputImage(image);
 filter.process();
 PixelImage sharpenedImage = filter.getOutputImage();
Use static convenience method on image img:
 PixelImage filteredImage = ConvolutionKernelFilter.filter(img, ConvolutionKernelFilter.TYPE_BLUR);
 

Credits

The implementation of the filter was created by members of the Java newsgroup de.comp.lang.java and adapted to the JIU framework by Marco Schmidt. As it was done in a contest style where people improved other people's work, and even more people suggested ideas, tested results and discussed the contest it is (1) hard to tell who won the contest and (2) only fair to list all persons involved.

The resulting implementation is significantly faster than the reference implementation. The contest was started by the posting [JPEC#3] Vorschläge to de.comp.lang.java by Marco Schmidt (2001-02-18) and was ended by the posting [JPEC#3] Ergebnisse (2001-03-07). A Usenet archive like Google Groups should be able to provide the postings.

Author:
Bernd Eckenfels, Carl Rosenberger, Dietmar Münzenberger, Karsten Schulz, Marco Kaiser, Marco Schmidt, Peter Luschny, Peter Schneider, Ramin Sadre, Roland Dieterich, Thilo Schwidurski
  • Field Details

    • TYPE_BLUR

      public static final int TYPE_BLUR
      See Also:
    • TYPE_SHARPEN

      public static final int TYPE_SHARPEN
      See Also:
    • TYPE_EDGE_DETECTION

      public static final int TYPE_EDGE_DETECTION
      See Also:
    • TYPE_EMBOSS

      public static final int TYPE_EMBOSS
      See Also:
    • TYPE_PSYCHEDELIC_DISTILLATION

      public static final int TYPE_PSYCHEDELIC_DISTILLATION
      See Also:
    • TYPE_LITHOGRAPH

      public static final int TYPE_LITHOGRAPH
      See Also:
    • TYPE_HORIZONTAL_SOBEL

      public static final int TYPE_HORIZONTAL_SOBEL
      See Also:
    • TYPE_VERTICAL_SOBEL

      public static final int TYPE_VERTICAL_SOBEL
      See Also:
    • TYPE_HORIZONTAL_PREWITT

      public static final int TYPE_HORIZONTAL_PREWITT
      See Also:
    • TYPE_VERTICAL_PREWITT

      public static final int TYPE_VERTICAL_PREWITT
      See Also:
    • BLUR_DATA

      private static final int[] BLUR_DATA
    • SHARPEN_DATA

      private static final int[] SHARPEN_DATA
    • EDGE_DETECTION_DATA

      private static final int[] EDGE_DETECTION_DATA
    • EMBOSS_DATA

      private static final int[] EMBOSS_DATA
    • PSYCHEDELIC_DISTILLATION_DATA

      private static final int[] PSYCHEDELIC_DISTILLATION_DATA
    • LITHOGRAPH_DATA

      private static final int[] LITHOGRAPH_DATA
    • HORIZONTAL_SOBEL_DATA

      private static final int[] HORIZONTAL_SOBEL_DATA
    • VERTICAL_SOBEL_DATA

      private static final int[] VERTICAL_SOBEL_DATA
    • HORIZONTAL_PREWITT_DATA

      private static final int[] HORIZONTAL_PREWITT_DATA
    • VERTICAL_PREWITT_DATA

      private static final int[] VERTICAL_PREWITT_DATA
    • PREDEFINED_KERNELS

      private static ConvolutionKernelData[] PREDEFINED_KERNELS
    • kernelBias

      private int kernelBias
    • kernelData

      private int[] kernelData
    • kernelDiv

      private int kernelDiv
    • kernelHeight

      private int kernelHeight
    • kernelWidth

      private int kernelWidth
  • Constructor Details

    • ConvolutionKernelFilter

      public ConvolutionKernelFilter()
  • Method Details

    • copyRow

      private void copyRow(IntegerImage srcImage, int srcChannelIndex, int rowIndex, int[] dest, int destOffset, int numBorderColumns)
      Copies row data from input image to buffer and replicates samples at the left and right border.
    • filter

      public static PixelImage filter(PixelImage input, int kernelType)
      Filters argument image with argument kernel type and returns output image. Static convenience method to do filtering with one line of code:
      PixelImage blurredImage = ConvolutionKernelFilter.filter(in, ConvolutionKernelFilter.TYPE_BLUR);
    • filter

      public static PixelImage filter(PixelImage input, ConvolutionKernelData data)
    • process

      private void process(int channelIndex, IntegerImage in, IntegerImage out)
      Applies the kernel to one of the channels of an image.
      Parameters:
      channelIndex - index of the channel to be filtered, must be from 0 to ByteChannelImage.getNumChannels() - 1
    • process

      private void process(IntegerImage in, IntegerImage out)
    • process

      public void process() throws MissingParameterException, WrongParameterException
      Description copied from class: Operation
      This method does the actual work of the operation. It must be called after all parameters have been given to the operation object.
      Overrides:
      process in class Operation
      Throws:
      MissingParameterException - if any mandatory parameter was not given to the operation
      WrongParameterException - if at least one of the input parameters was not initialized appropriately (values out of the valid interval, etc.)
    • setKernel

      public void setKernel(int[] data, int width, int height, int div, int bias)
      Sets properties of the kernel to be used in this operation.
      Parameters:
      data - the kernel coefficients; this one-dimensional array stores them in order top-to-bottom, left-to-right; the length of this array must be at least width times height
      width - the width of the kernel; must not be even
      height - the height of the kernel; must not be even
      div - the result is divided by this value after the addition of value (so this value must not be zero)
      bias - this value is added to the result before the division
    • setKernel

      public void setKernel(ConvolutionKernelData ckd)
      Sets kernel data to be used for filtering.
      Parameters:
      ckd - all information necessary for filtering
    • setKernel

      public void setKernel(int type)
      Sets one of the predefined kernel types to be used for filtering.
      Parameters:
      type - one of the TYPE_xyz constants of this class
      Throws:
      IllegalArgumentException - if the argument is not a valid TYPE_xyz constant