com.idrsolutions.image.png.D3 Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of OpenViewerFX Show documentation
An Open Source JavaFX PDF Viewer
The newest version!
/*
 * ===========================================
 * Java Pdf Extraction Decoding Access Library
 * ===========================================
 *
 * Project Info:  http://www.idrsolutions.com
 * Help section for developers at http://www.idrsolutions.com/support/
 *
 * (C) Copyright 1997-2015 IDRsolutions and Contributors.
 *
 * This file is part of JPedal/JPDF2HTML5
 *
     This library 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 2.1 of the License, or (at your option) any later version.

    This library 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 GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


 *
 * ---------------
 * D3.java
 * ---------------
 */
package com.idrsolutions.image.png;

/**
 * Class performs dithering in 24 bit images
 */
public class D3 {
    
    public final int r;
    public final int g;
    public final int b;
    public final int rgb;
    
    public D3(int r,int g, int b){
        this.r = r;
        this.g = g;
        this.b = b;
        this.rgb = (r << 16) | (g << 8) | b;
    }

    private static int diff(int r, int g, int b, D3 pal) {        
        int Rdiff = r - pal.r;
        int Gdiff = g - pal.g;
        int Bdiff = b - pal.b;
        return Rdiff * Rdiff + Gdiff * Gdiff + Bdiff * Bdiff;
    }
    
    public static int[] findClosest(int argb, D3[] palette) {
        D3 closest = palette[0];
        D3 n;
        int r = (argb>> 16) & 0xff;
        int g = (argb >> 8) & 0xff;
        int b = argb & 0xff;
        int cDiff = diff(r,g,b,closest);
        int nDiff;
        int found = 0;
        for (int i = 1; i < 256; i++) {
            n = palette[i];
            nDiff = diff(r,g,b,n);

            if (nDiff < cDiff) {
                closest = n;
                found = i;
                cDiff = nDiff;
            }
        }
        return new int[]{closest.rgb, found};
    }

    public static byte[] process(byte[] colorPalette, int[][] image, int h, int w) {

        int p = 0;
        D3[] palette = new D3[256];
        for (int i = 0; i < 256; i++) {
            int r = colorPalette[p++] & 0xff;
            int g = colorPalette[p++] & 0xff;
            int b = colorPalette[p++] & 0xff;
            palette[i] = new D3(r, g, b);
        }

        byte[] indexedPixels = new byte[h * w];
        p = 0;
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w; x++) {
                final int argb = image[y][x];

//                byte bb = wu.findMatch(argb);
//                indexedPixels[p++] = bb;
//                int nextArgb = palette[bb&0xff].rgb;
                
                int[] obj = findClosest(argb, palette);
                int nextArgb = obj[0];
                indexedPixels[p++] = (byte) obj[1];

                int r = (argb >> 16) & 0xff;
                int g = (argb >> 8) & 0xff;
                int b = argb & 0xff;

                int nr = (nextArgb >> 16) & 0xff;
                int ng = (nextArgb >> 8) & 0xff;
                int nb = nextArgb & 0xff;

                int errR = r - nr;
                int errG = g - ng;
                int errB = b - nb;

                if (x + 1 < w) {
                    int update = applyFloyd(image[y][x + 1], errR, errG, errB, 7);
                    image[y][x + 1] = update;
                    if (y + 1 < h) {
                        update = applyFloyd(image[y + 1][x + 1], errR, errG, errB, 1);
                        image[y + 1][x + 1] = update;
                    }
                }
                if (y + 1 < h) {
                    int update = applyFloyd(image[y + 1][x], errR, errG, errB, 5);
                    image[y + 1][x] = update;
                    if (x - 1 >= 0) {
                        update = applyFloyd(image[y + 1][x - 1], errR, errG, errB, 3);
                        image[y + 1][x - 1] = update;
                    }
                }
            }
        }
        return indexedPixels;
    }

    private static int applyFloyd(final int argb, final int errR, final int errG, final int errB, final int mul) {
        int r = (argb >> 16) & 0xff;
        int g = (argb >> 8) & 0xff;
        int b = argb & 0xff;

        r += errR * mul / 16;
        g += errG * mul / 16;
        b += errB * mul / 16;

        if (r < 0) {
            r = 0;
        } else if (r > 0xff) {
            r = 0xff;
        }
        if (g < 0) {
            g = 0;
        } else if (g > 0xff) {
            g = 0xff;
        }
        if (b < 0) {
            b = 0;
        } else if (b > 0xff) {
            b = 0xff;
        }

        return (r << 16) | (g << 8) | b;
    }

}