/*
* $RCSfile: GradientMagnitudeDescriptor.java,v $
*
* Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
*
* Use is subject to license terms.
*
* $Revision: 1.1 $
* $Date: 2005/02/11 04:57:36 $
* $State: Exp $
*/
package com.lightcrafts.mediax.jai.operator;
import com.lightcrafts.media.jai.util.AreaOpPropertyGenerator;
import java.awt.RenderingHints;
import java.awt.image.RenderedImage;
import java.awt.image.renderable.ParameterBlock;
import com.lightcrafts.mediax.jai.JAI;
import com.lightcrafts.mediax.jai.KernelJAI;
import com.lightcrafts.mediax.jai.OperationDescriptorImpl;
import com.lightcrafts.mediax.jai.ParameterBlockJAI;
import com.lightcrafts.mediax.jai.PropertyGenerator;
import com.lightcrafts.mediax.jai.RenderedOp;
import com.lightcrafts.mediax.jai.registry.RenderedRegistryMode;
/**
* An <code>OperationDescriptor</code> describing the "GradientMagnitude"
* operation.
*
* <p> The "GradientMagnitude" operation is an edge detector which computes
* the magnitude of the image gradient vector in two orthogonal directions.
*
* <p> The result of the "GradientMagnitude" operation may be defined as:
* <pre>
* dst[x][y][b] = ((SH(x,y,b))^2 + (SV(x,y,b))^2 )^0.5
* </pre>
*
* where SH(x,y,b) and SV(x,y,b) are the horizontal and vertical gradient
* images generated from band <i>b</i> of the source image by correlating it
* with the supplied orthogonal (horizontal and vertical) gradient masks.
*
* Origins set on the kernels will be ignored. The origins are assumed to be
* width/2 & height/2.
*
* It should be noted that this operation automatically adds a
* value of <code>Boolean.TRUE</code> for the
* <code>JAI.KEY_REPLACE_INDEX_COLOR_MODEL</code> to the given
* <code>configuration</code> so that the operation is performed
* on the pixel values instead of being performed on the indices into
* the color map if the source(s) have an <code>IndexColorModel</code>.
* This addition will take place only if a value for the
* <code>JAI.KEY_REPLACE_INDEX_COLOR_MODEL</code> has not already been
* provided by the user. Note that the <code>configuration</code> Map
* is cloned before the new hint is added to it. The operation can be
* smart about the value of the <code>JAI.KEY_REPLACE_INDEX_COLOR_MODEL</code>
* <code>RenderingHints</code>, i.e. while the default value for the
* <code>JAI.KEY_REPLACE_INDEX_COLOR_MODEL</code> is
* <code>Boolean.TRUE</code>, in some cases the operator could set the
* default.
*
* <p><table align=center border=1>
* <caption>Resource List</caption>
* <tr><th>Name</th> <th>Value</th></tr>
* <tr><td>GlobalName</td> <td>GradientMagnitude</td></tr>
* <tr><td>LocallName</td> <td>GradientMagnitude</td></tr>
* <tr><td>Vendor</td> <td>com.lightcrafts.media.jai</td></tr>
* <tr><td>Description</td> <td>Performs gradient magnitude edge detection
* on an image.</td></tr>
* <tr><td>DocURL</td> <td>http://java.sun.com/products/java-media/jai/forDevelopers/jaiapi/com.lightcrafts.mediax.jai.operator.GradientMagnitudeDescriptor.html</td></tr>
* <tr><td>Version</td> <td>1.0</td></tr>
* <tr><td>arg0Desc</td> <td>A gradient mask</td></tr>
* <tr><td>arg1Desc</td> <td>A gradient mask orthogonal to the first one.</td></tr>
* </table></p>
*
* <p><table border=1>
* <caption>Parameter List</caption>
* <tr><th>Name</th> <th>Class Type</th>
* <th>Default Value</th></tr>
* <tr><td>mask1</td> <td>com.lightcrafts.mediax.jai.KernelJAI</td>
* <td>KernalJAI.GRADIENT_MASK_SOBEL_HORIZONTAL</td>
* <tr><td>mask2</td> <td>com.lightcrafts.mediax.jai.KernelJAI</td>
* <td>KernalJAI.GRADIENT_MASK_SOBEL_VERTICAL</td>
* </table></p>
*
* @see com.lightcrafts.mediax.jai.OperationDescriptor
* @see com.lightcrafts.mediax.jai.KernelJAI
*/
public class GradientMagnitudeDescriptor extends OperationDescriptorImpl {
/**
* The resource strings that provide the general documentation
* and specify the parameter list for the GradientMagnitude operation.
*/
private static final String[][] resources = {
{"GlobalName", "GradientMagnitude"},
{"LocalName", "GradientMagnitude"},
{"Vendor", "com.lightcrafts.media.jai"},
{"Description", JaiI18N.getString("GradientMagnitudeDescriptor0")},
{"DocURL", "http://java.sun.com/products/java-media/jai/forDevelopers/jaiapi/com.lightcrafts.mediax.jai.operator.GradientMagnitudeDescriptor.html"},
{"Version", JaiI18N.getString("DescriptorVersion")},
{"arg0Desc", "A gradient mask."},
{"arg1Desc", "A gradient mask orthogonal to the first one."}
};
/** The parameter names for the GradientMagnitude operation. */
private static final String[] paramNames = {
"mask1",
"mask2"
};
/** The parameter class types for the GradientMagnitude operation. */
private static final Class[] paramClasses = {
com.lightcrafts.mediax.jai.KernelJAI.class,
com.lightcrafts.mediax.jai.KernelJAI.class
};
/** The parameter default values for the GradientMagnitude operation. */
private static final Object[] paramDefaults = {
KernelJAI.GRADIENT_MASK_SOBEL_HORIZONTAL,
KernelJAI.GRADIENT_MASK_SOBEL_VERTICAL
};
/** Constructor for the GradientMagnitudeDescriptor. */
public GradientMagnitudeDescriptor() {
super(resources, 1, paramClasses, paramNames, paramDefaults);
}
/**
* Validates the input parameters.
*
* <p> In addition to the standard checks performed by the
* superclass method, this method checks that "mask1" and "mask2"
* have the same dimensions.
*/
protected boolean validateParameters(ParameterBlock args,
StringBuffer msg) {
if (!super.validateParameters(args, msg)) {
return false;
}
KernelJAI h_kernel = (KernelJAI)args.getObjectParameter(0);
KernelJAI v_kernel = (KernelJAI)args.getObjectParameter(1);
/* Check if both kernels are equivalent in terms of dimensions. */
if ((h_kernel.getWidth() != v_kernel.getWidth()) ||
(h_kernel.getHeight() != v_kernel.getHeight())) {
msg.append(getName() + " " +
JaiI18N.getString("GradientMagnitudeDescriptor1"));
return false;
}
return true;
}
/**
* Returns an array of <code>PropertyGenerators</code> implementing
* property inheritance for the "GradientMagnitude" operation.
*
* @return An array of property generators.
*/
public PropertyGenerator[] getPropertyGenerators() {
PropertyGenerator[] pg = new PropertyGenerator[1];
pg[0] = new AreaOpPropertyGenerator();
return pg;
}
/**
* Computes the gradient of an image
*
* <p>Creates a <code>ParameterBlockJAI</code> from all
* supplied arguments except <code>hints</code> and invokes
* {@link JAI#create(String,ParameterBlock,RenderingHints)}.
*
* @see JAI
* @see ParameterBlockJAI
* @see RenderedOp
*
* @param source0 <code>RenderedImage</code> source 0.
* @param mask1 A gradient mask.
* May be <code>null</code>.
* @param mask2 A gradient mask orthogonal to the first one.
* May be <code>null</code>.
* @param hints The <code>RenderingHints</code> to use.
* May be <code>null</code>.
* @return The <code>RenderedOp</code> destination.
* @throws IllegalArgumentException if <code>source0</code> is <code>null</code>.
*/
public static RenderedOp create(RenderedImage source0,
KernelJAI mask1,
KernelJAI mask2,
RenderingHints hints) {
ParameterBlockJAI pb =
new ParameterBlockJAI("GradientMagnitude",
RenderedRegistryMode.MODE_NAME);
pb.setSource("source0", source0);
pb.setParameter("mask1", mask1);
pb.setParameter("mask2", mask2);
return JAI.create("GradientMagnitude", pb, hints);
}
}