1 /* 2 * $RCSfile: UnsharpMaskDescriptor.java,v $ 3 * 4 * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved. 5 * 6 * Use is subject to license terms. 7 * 8 * $Revision: 1.1 $ 9 * $Date: 2005/02/11 04:57:46 $ 10 * $State: Exp $ 11 */ 12 package com.lightcrafts.mediax.jai.operator; 13 14 import com.lightcrafts.media.jai.util.AreaOpPropertyGenerator; 15 import java.awt.RenderingHints; 16 import java.awt.image.RenderedImage; 17 import com.lightcrafts.mediax.jai.JAI; 18 import com.lightcrafts.mediax.jai.KernelJAI; 19 import com.lightcrafts.mediax.jai.OperationDescriptorImpl; 20 import com.lightcrafts.mediax.jai.ParameterBlockJAI; 21 import com.lightcrafts.mediax.jai.PropertyGenerator; 22 import com.lightcrafts.mediax.jai.RenderedOp; 23 import com.lightcrafts.mediax.jai.registry.RenderedRegistryMode; 24 25 /** 26 * <p>An <code>OperationDescriptor</code> describing the "UnsharpMask" operation. 27 * 28 * <p> Unsharp masking is derived from a photographic technique for 29 * improving the sharpness of images. In its digital form it is implemented 30 * using convolution to create a low-pass filtered version of a source image. 31 * The low-pass image is then subtracted from the original image, 32 * creating a high-pass image. The high pass image is then added back 33 * to the original image, creating enhanced edge contrast. By adjusting 34 * a scaling factor, the degree of high pass add-back can be controlled. 35 * 36 * <p>The operation is implemented algorithmically as follows. At each 37 * original pixel location x,y: 38 * 39 * <pre> 40 * result = original + (original - lowpass) * gainFactor 41 * 42 * where 43 * original = value at position x,y of source image 44 * lowpass = result of convolution with lowpass filter 45 * centered at pixel x,y 46 * gain = controlling parameter for degree of sharpness 47 * gain = 0 : no effect 48 * gain > 0 : sharpening 49 * -1 < gain < 0 : smoothing 50 * </pre> 51 * <p> In general gain factors should be restricted to a range of 52 * [-1, 2], as higher magnitude values are likely to cause 53 * overflows or underflows which must be clamped to the image 54 * data type's range. 55 * 56 * <p> The default gain factor is set to <code>1,0F</code>. 57 * 58 * <p> This operation is widely applied to scanned image enhancement. 59 * The typical gain factor for scanned images takes values in the range 60 * of [1/4, 2] (page 278 in Digital Image Processing by William 61 * K. Pratt, 3rd). 62 * 63 * <p><table border=1> 64 * <caption>Resource List</caption> 65 * <tr><th>Name</th> <th>Value</th></tr> 66 * <tr><td>GlobalName</td> <td>UnsharpMask</td></tr> 67 * <tr><td>LocalName</td> <td>UnsharpMask</td></tr> 68 * <tr><td>Vendor</td> <td>com.lightcrafts.media.jai</td></tr> 69 * <tr><td>Description</td> <td>Performs unsharp masking to sharpen or smooth 70 * an image.</td></tr> 71 * <tr><td>DocURL</td> <td>http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/UnsharpMaskDescriptor.html</td></tr> 72 * <tr><td>Version</td> <td>1.1</td></tr> 73 * <tr><td>arg0Desc</td> <td>The convolution kernel.</td></tr> 74 * <tr><td>arg1Desc</td> <td>The gain factor.</td></tr> 75 * </table></p> 76 * 77 * <p><table border=1> 78 * <caption>Parameter List</caption> 79 * <tr><th>Name</th> <th>Class Type</th> 80 * <th>Default Value</th></tr> 81 * <tr><td>kernel</td> <td>com.lightcrafts.mediax.jai.KernelJAI</td> 82 * <td>3 X 3 average</td> 83 * <tr><td>gain</td> <td>java.lang.Float</td> 84 * <td>1.0F</td> 85 * </table></p> 86 * 87 * @see com.lightcrafts.mediax.jai.OperationDescriptor 88 * @see com.lightcrafts.mediax.jai.KernelJAI 89 * @see com.lightcrafts.mediax.jai.operator.ConvolveDescriptor 90 * 91 * @since JAI 1.1 92 */ 93 public class UnsharpMaskDescriptor extends OperationDescriptorImpl { 94 95 /** 96 * The resource strings that provide the general documentation and 97 * specify the parameter list for a UnsharpMask operation. 98 */ 99 private static final String[][] resources = { 100 {"GlobalName", "UnsharpMask"}, 101 {"LocalName", "UnsharpMask"}, 102 {"Vendor", "com.lightcrafts.media.jai"}, 103 {"Description", JaiI18N.getString("UnsharpMaskDescriptor0")}, 104 {"DocURL", "http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/UnsharpMaskDescriptor.html"}, 105 {"Version", JaiI18N.getString("DescriptorVersion")}, 106 {"arg0Desc", JaiI18N.getString("UnsharpMaskDescriptor1")}, 107 {"arg1Desc", JaiI18N.getString("UnsharpMaskDescriptor2")} 108 }; 109 110 /** The parameter names for the UnsharpMask operation. */ 111 private static final String[] paramNames = { 112 "kernel", "gain" 113 }; 114 115 /** The parameter class types for the UnsharpMask operation. */ 116 private static final Class[] paramClasses = { 117 com.lightcrafts.mediax.jai.KernelJAI.class, 118 java.lang.Float.class 119 }; 120 121 /** The parameter default values for the UnsharpMask operation. */ 122 private static final Object[] paramDefaults = { 123 new KernelJAI(3, 3, 1, 1, new float[]{1/9F, 1/9F, 1/9F, 1/9F, 1/9F, 1/9F, 1/9F, 1/9F, 1/9F}), 124 new Float(1.0F) 125 }; 126 127 /** Constructor. */ UnsharpMaskDescriptor()128 public UnsharpMaskDescriptor() { 129 super(resources, 1, paramClasses, paramNames, paramDefaults); 130 } 131 132 /** 133 * Returns an array of <code>PropertyGenerators</code> implementing 134 * property inheritance for the "UnsharpMask" operation. 135 * 136 * @return An array of property generators. 137 */ getPropertyGenerators()138 public PropertyGenerator[] getPropertyGenerators() { 139 PropertyGenerator[] pg = new PropertyGenerator[1]; 140 pg[0] = new AreaOpPropertyGenerator(); 141 return pg; 142 } 143 144 145 /** 146 * Performs UnsharpMask operation on the image. 147 * 148 * <p>Creates a <code>ParameterBlockJAI</code> from all 149 * supplied arguments except <code>hints</code> and invokes 150 * {@link JAI#create(String,ParameterBlock,RenderingHints)}. 151 * 152 * @see JAI 153 * @see ParameterBlockJAI 154 * @see RenderedOp 155 * 156 * @param source0 <code>RenderedImage</code> source 0. 157 * @param kernel The low-pass convolution kernel. 158 * May be <code>null</code>. 159 * @param gain The sharpening value. 160 * May be <code>null</code>. 161 * @param hints The <code>RenderingHints</code> to use. 162 * May be <code>null</code>. 163 * @return The <code>RenderedOp</code> destination. 164 * @throws IllegalArgumentException if <code>source0</code> is <code>null</code>. 165 */ create(RenderedImage source0, KernelJAI kernel, Float gain, RenderingHints hints)166 public static RenderedOp create(RenderedImage source0, 167 KernelJAI kernel, 168 Float gain, 169 RenderingHints hints) { 170 ParameterBlockJAI pb = 171 new ParameterBlockJAI("UnsharpMask", 172 RenderedRegistryMode.MODE_NAME); 173 174 pb.setSource("source0", source0); 175 176 pb.setParameter("kernel", kernel); 177 pb.setParameter("gain", gain); 178 179 return JAI.create("UnsharpMask", pb, hints); 180 } 181 } 182