RgbGray8ApplyMask.java

/*
 * RgbGray8ApplyMask.java
 *   Shows a mask on an RgbImage by making all the unmasked pixels gray.
 *   This is not a pipeline stage since it takes two images.
 *
 * Created on August 27, 2006, 9:02 AM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 *
 * Copyright 2007 by Jon A. Webb
 *     This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the Lesser GNU General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
*/

package jjil.algorithm;
import jjil.core.Error;
import jjil.core.Gray8Image;
import jjil.core.RgbImage;
import jjil.core.RgbVal;
/** RgbGray8ApplyMask shows a mask on an RgbImage by making all the unmasked pixels gray.
 *   This is not a pipeline stage since it takes two images.
 * @author webb
 */
public class RgbGray8ApplyMask {
    
    /** Creates a new instance of RgbGray8ApplyMask */
    public RgbGray8ApplyMask() {
    }
    
    /**
     * Highlights an area in a RgbImage by turning the non-masked areas gray and dimming them.
     * @return the masked color image.
     * @param imRgb the input RgbImage.
     * @param imMask The input mask. Pixels with the value Byte.MIN_VALUE are 
     * unmasked. Everything else is considered to be masked.
     * @throws jjil.core.Error if the input sizes do not match
     */
    public RgbImage push(
            RgbImage imRgb,
            Gray8Image imMask) throws jjil.core.Error {
        if (imRgb.getWidth() != imMask.getWidth() ||
            imRgb.getHeight() != imMask.getHeight()) {
            throw new Error(
                            Error.PACKAGE.CORE,
                            jjil.core.ErrorCodes.IMAGE_MASK_SIZE_MISMATCH,
                            imRgb.toString(),
                            imMask.toString(),
                            null);
        }
        int[] rgbData = imRgb.getData();
        byte[] maskData = imMask.getData();
        for (int i=0; i<imRgb.getWidth() * imRgb.getHeight(); i++) {
            if (maskData[i] == Byte.MIN_VALUE) {
                /* get individual r, g, and b values, unmasking them from the
                 * ARGB word and converting to an unsigned byte.
                 */
                int r = RgbVal.getR(rgbData[i]) - Byte.MIN_VALUE;
                int g = RgbVal.getG(rgbData[i]) - Byte.MIN_VALUE;
                int b = RgbVal.getB(rgbData[i]) - Byte.MIN_VALUE;
                // also darken unmasked pixels
                int gray = (r + g + b) / 5;
                /* average the values to get the grayvalue
                 */
                    /* Create ARGB word */
                    rgbData[i] = 
                            ((gray)<<16) | 
                            ((gray)<<8) | 
                            gray;

            }
        }
        return imRgb;
    }
}