com.github.ojil.algorithm.RgbSelectGray Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of ojil-core Show documentation
Open Java Imaging Library.
There is a newer version: 0.0.11
/*
 * RgbSelectGray.java
 *
 * Created on August 27, 2006, 11:33 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 .
 *
 */

package com.github.ojil.algorithm;

import com.github.ojil.core.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.ImageError;
import com.github.ojil.core.PipelineStage;
import com.github.ojil.core.RgbImage;
import com.github.ojil.core.RgbVal;

/**
 * 
 * Transforms a RgbImage into a Gray8Image by selecting one of the three bands.
 * The pixel value chosen is adjusted from the range 0→255 to the range
 * -128→127.
 * 
 * 
 * Usage: 

 * 
 * 
 *        RgbImage imageRgb = ...;

 *        RgbSelectGray rgb = new RgbSelectGray(RgbSelectGray.RED);

 *        rgb.push(imageRgb);
 *    
 * 
 * 
 * @author webb
 */
public class RgbSelectGray extends PipelineStage {
    /*
     * In the absence of enums in version 1.3 we use three empty singleton
     * classes to represent the color choice.
     */
    /**
     * Used to represent the three colors red, green, or blue.
     */
    public static class ColorClass {
        private final String name;
        private static final ColorClass RED = new ColorClass("RED");
        private static final ColorClass GREEN = new ColorClass("GREEN");
        private static final ColorClass BLUE = new ColorClass("BLUE");
        
        private ColorClass(final String name) {
            this.name = name;
        }
        
        /**
         * Represents the color red.
         * 
         * @return A ColorClass object that represents the color red.
         */
        public static ColorClass Red() {
            return ColorClass.RED;
        }
        
        /**
         * Represents the color green.
         * 
         * @return A ColorClass object that represents the color green.
         */
        public static ColorClass Green() {
            return ColorClass.GREEN;
        }
        
        /**
         * Represents the color blue.
         * 
         * @return A ColorClass object that represents the color blue.
         */
        public static ColorClass Blue() {
            return ColorClass.BLUE;
        }
        
        /**
         * Returns a string representation of the RgbSelectGray operation.
         * 
         * @return a String representing the RgbSelectGray operation.
         */
        @Override
        public String toString() {
            return name;
        }
    };
    
    /**
     * The class represents the color red. It is used like an enumerated value
     * when calling the RgbSelectGray constructor.
     */
    public static final ColorClass RED = ColorClass.Red();
    
    /**
     * The class represents the color green. It is used like an enumerated value
     * when calling the RgbSelectGray constructor.
     */
    public static final ColorClass GREEN = ColorClass.Green();
    /**
     * The class represents the color blue. It is used like an enumerated value
     * when calling the RgbSelectGray constructor.
     */
    public static final ColorClass BLUE = ColorClass.Blue();
    
    /**
     * Aliases for red, green, and blue used when we're thinking of the RGB
     * image as an HSV image.
     */
    public static final ColorClass HUE = ColorClass.Red();
    public static final ColorClass SATURATION = ColorClass.Green();
    public static final ColorClass VALUE = ColorClass.Blue();
    
    private ColorClass colorChosen;
    
    /**
     * Creates a new instance of RgbSelectGray.
     * 
     * @param color
     *            the color selected from the color image to create the gray
     *            image.
     * @throws ImageError
     *             if color is not RED, GREEN, or BLUE.
     */
    public RgbSelectGray(final ColorClass color) throws ImageError {
        setColor(color);
    }
    
    /**
     * Returns the current color selected.
     *
     * @return the current color, as a ColorClass object.
     */
    public ColorClass getColor() {
        return colorChosen;
    }
    
    /**
     * Convert a color image to gray by selecting one of the color bands: red,
     * green, or blue. The band selected is chosen in the class constructor. The
     * gray pixel value is adjusted so its range is from -128→127 instead
     * of the 0-255 value in the ARGB word.
     *
     * @param image
     *            the input image
     * @throws ImageError
     *             if the input image is not a color image.
     */
    @Override
    public void push(final Image image) throws ImageError {
        if (!(image instanceof RgbImage)) {
            throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.IMAGE_NOT_RGBIMAGE, image.toString(), null, null);
        }
        final RgbImage rgb = (RgbImage) image;
        final Integer[] rgbData = rgb.getData();
        final Gray8Image gray = new Gray8Image<>(image.getWidth(), image.getHeight());
        final Byte[] grayData = gray.getData();
        if (colorChosen.equals(RgbSelectGray.RED)) {
            for (int i = 0; i < (image.getWidth() * image.getHeight()); i++) {
                /*
                 * get individual color value, unmasking it from the ARGB word
                 */
                grayData[i] = RgbVal.getR(rgbData[i]);
            }
        } else if (colorChosen.equals(RgbSelectGray.GREEN)) {
            for (int i = 0; i < (image.getWidth() * image.getHeight()); i++) {
                /*
                 * get individual color value, unmasking it from the ARGB word
                 */
                grayData[i] = RgbVal.getG(rgbData[i]);
            }
        } else /* must be BLUE, from constructor */{
            for (int i = 0; i < (image.getWidth() * image.getHeight()); i++) {
                /*
                 * get individual color value, unmasking it from the ARGB word
                 */
                grayData[i] = RgbVal.getB(rgbData[i]);
            }
        }
        super.setOutput(gray);
    }
    
    /**
     * Changes the color selected.
     * 
     * @param color
     *            the new color selected
     * @throws ImageError
     *             if the input color is not ColorClass.RED, GREEN, or BLUE.
     */
    public void setColor(final ColorClass color) throws ImageError {
        /*
         * as I understand the language this can't happen, but just in case...
         */
        if (!(color.equals(RgbSelectGray.RED) || color.equals(RgbSelectGray.GREEN) || color.equals(RgbSelectGray.BLUE))) {
            throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.ILLEGAL_COLOR_CHOICE, color.toString(), null, null);
            
        }
        colorChosen = color;
    }
    
    /**
     * Return a string describing the RGB select operation.
     *
     * @return the string describing the RGB select operation.
     */
    @Override
    public String toString() {
        return super.toString() + " (" + colorChosen.toString() + //$NON-NLS-1$
                ")"; //$NON-NLS-1$
    }
    
}