001/*******************************************************************************
002 * This software is provided as a supplement to the authors' textbooks on digital
003 * image processing published by Springer-Verlag in various languages and editions.
004 * Permission to use and distribute this software is granted under the BSD 2-Clause
005 * "Simplified" License (see http://opensource.org/licenses/BSD-2-Clause).
006 * Copyright (c) 2006-2023 Wilhelm Burger, Mark J. Burge. All rights reserved.
007 * Visit https://imagingbook.com for additional details.
008 ******************************************************************************/
009package Ch03_Point_Operations;
010
011import ij.ImagePlus;
012import ij.gui.GenericDialog;
013import ij.plugin.filter.PlugInFilter;
014import ij.process.ImageProcessor;
015import imagingbook.common.ij.DialogUtils;
016import imagingbook.core.jdoc.JavaDocHelp;
017import imagingbook.sampleimages.GeneralSampleImage;
018
019import static imagingbook.common.ij.IjUtils.noCurrentImage;
020
021/**
022 * <p>
023 * This ImageJ performs simple gamma correction (with fixed &gamma; = 2.8) on
024 * a 8-bit grayscale image, which is modified.
025 * See Sec. 3.7 (Prog. 3.4) of [1] for additional details.
026 * </p>
027 * <p>
028 * [1] W. Burger, M.J. Burge, <em>Digital Image Processing &ndash; An Algorithmic Introduction</em>,
029 * 3rd ed, Springer (2022).
030 * </p>
031 * @author WB
032 *
033 */
034public class Gamma_Correction implements PlugInFilter, JavaDocHelp {
035        
036        private static double GAMMA = 2.8;
037
038        /** Constructor, asks to open a predefined sample image if no other image is currently open. */
039        public Gamma_Correction() {
040                if (noCurrentImage()) {
041                        DialogUtils.askForSampleImage(GeneralSampleImage.IrishManor);
042                }
043        }
044
045        @Override
046        public int setup(String arg, ImagePlus im) {
047                return DOES_8G;
048        }
049    
050        @Override
051        public void run(ImageProcessor ip) {
052                if (!runDialog()) {
053                        return;
054                }
055
056                // works for 8-bit images only 
057            int K = 256;
058            int aMax = K - 1;
059        
060            // create and fill the lookup table:
061            int[] Fgc = new int[K];                
062        
063            for (int a = 0; a < K; a++) {
064                double aa = (double) a / aMax;          // scale to [0,1]
065                double bb = Math.pow(aa, GAMMA);        // power function
066                // scale back to [0,255]
067                int b = (int) Math.round(bb * aMax); 
068                Fgc[a] = b;  
069            }
070            
071            ip.applyTable(Fgc);  // modify the image
072        }
073
074        private boolean runDialog() {
075                GenericDialog gd = new GenericDialog(this.getClass().getSimpleName());
076                gd.addHelp(getJavaDocUrl());
077                gd.addNumericField("gamma (\u03B3 > 0)", GAMMA, 2);
078
079                gd.showDialog();
080                if (gd.wasCanceled())
081                        return false;
082
083                GAMMA = gd.getNextNumber();
084                return true;
085        }
086}