/* Change the contrast of an image.
 @Copyright (c) 1998-2005 The Regents of the University of California.
 All rights reserved.

 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the
 above copyright notice and the following two paragraphs appear in all
 copies of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION 2
 COPYRIGHTENDKEY
 */
package ptolemy.domains.sdf.lib.vq;

import ptolemy.actor.lib.Transformer;
import ptolemy.data.IntMatrixToken;
import ptolemy.data.type.BaseType;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;

//////////////////////////////////////////////////////////////////////////
//// ImageContrast

/**
 Change the contrast of an image.

 <p>If the input image has a lot of pixels with the same or similar color,
 This actor uses gray scale equalization to redistribute the value of each
 pixel between 0 and 255.

 @author Michael Leung, Steve Neuendorffer
 @version $Id$
 @since Ptolemy II 0.2
 @Pt.ProposedRating Red (mikele)
 @Pt.AcceptedRating Red (cxh)
 */
public class ImageContrast extends Transformer {
    /** Construct an actor with the given container and name.
     *  @param container The container.
     *  @param name The name of this actor.
     *  @exception IllegalActionException If the actor cannot be contained
     *   by the proposed container.
     *  @exception NameDuplicationException If the container already has an
     *   actor with this name.
     */
    public ImageContrast(CompositeEntity container, String name)
            throws IllegalActionException, NameDuplicationException {
        super(container, name);

        output.setTypeEquals(BaseType.INT_MATRIX);
        input.setTypeEquals(BaseType.INT_MATRIX);
    }

    ///////////////////////////////////////////////////////////////////
    ////                         public variables                  ////
    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Fire the actor.
     *  Consume one image on the input port.
     *
     *  Summary:
     *  Contrast the image so that
     *  an more evenly color distributed image can be obtained.
     *  Assume that color is bounded from 0 to 255 inclusively.
     *  @exception IllegalActionException If image color is out-of-bound.
     *
     *  Algorithm:
     *  Construct a color histogram for the input image.
     *  Construct a cdf for the color histogram.
     *  Using Gray Scale Equalization, re-map each image pixel color.
     *
     *  Send the new image out the output port.
     */
    public void fire() throws IllegalActionException {
        super.fire();
        int i;
        int j;
        int[][] frame;
        int frameElement;

        IntMatrixToken message = (IntMatrixToken) input.get(0);
        frame = message.intMatrix();

        // Construct a color distribution histogram for the input image:
        // Assuming the color bound for the input 0 and 255. If color detected
        // that has color either bigger than 255 OR small than 0, then throw an
        // illegal action exception.
        for (i = 0; i < 256; i++) {
            colorHistogram[i] = 0;
        }

        int pixels = frame.length * frame[0].length;

        for (i = 0; i < frame.length; i++) {
            for (j = 0; j < frame[i].length; j++) {
                frameElement = frame[i][j];

                if ((frameElement < 0) || (frameElement > 255)) {
                    throw new IllegalActionException("ImageContrast:"
                            + "input image pixel contains at" + j + "," + i
                            + "with value" + frameElement
                            + "that is out of bounds."
                            + " Not between 0 and 255.");
                }

                colorHistogram[frameElement]++;
            }
        }

        //Construct the cdf of the color distribution histogram
        //colorHistogram[0] = colorHistogram[0]
        for (i = 1; i < 256; i++) {
            colorHistogram[i] = colorHistogram[i - 1] + colorHistogram[i];
        }

        // Search each pixel in the image and re-map it to a new
        // color number to make a new relatively even color distribution
        // image.
        int distributionConstant = pixels / 255;

        for (i = 0; i < frame.length; i++) {
            for (j = 0; j < frame[i].length; j++) {
                frameElement = frame[i][j];
                frame[i][j] = colorHistogram[frameElement]
                        / distributionConstant;
            }
        }

        message = new IntMatrixToken(frame);
        output.send(0, message);
    }

    ///////////////////////////////////////////////////////////////////
    ////                         private variables                 ////
    private int[] colorHistogram = new int[256];
}