javax.media.jai.operator
Class SubsampleBinaryToGrayDescriptor

java.lang.Object
  |
  +--javax.media.jai.OperationDescriptorImpl
        |
        +--javax.media.jai.operator.SubsampleBinaryToGrayDescriptor

All Implemented Interfaces:

OperationDescriptor, RegistryElementDescriptor, Serializable

public class SubsampleBinaryToGrayDescriptor

extends OperationDescriptorImpl

An OperationDescriptor describing the "SubsampleBinaryToGray" operation.

The "SubsampleBinaryToGray" operation collects a Binary image pixels into a gray scale image. Roughly speaking, each pixel (x, y) of the destination, is the sum of the source pixel values of the source pixel matrix of size 1/xScale by 1/yScale. In the noninteger case, the next bigger inter is used. Thus when xScale = yScale = 1/2.2, a 3 x 3 pixel matrix into a single destination pixel, resulting in 10 levels [0..9]. The resulting gray values are then normalized to have gray values in [0..255].

The source is a Binary image and the result of the operation is a grayscale image. The scale factors xScale and yScale must be between (0, 1] and strictly bigger than 0.

The destination image is a byte image whose dimensions are:

       dstWidth  = floor(srcWidth * xScale)
       dstHeight = floor(srcHeight * yScale)
 

It may be noted that the minX, minY, width and height hints as specified through the JAI.KEY_IMAGE_LAYOUT hint in the RenderingHints object are not honored, as this operator calculates the destination image bounds itself. The other ImageLayout hints, like tileWidth and tileHeight, however, are honored.

Specifying a scale factor of greater than 1 or less than 0 will cause an exception. To scale image sizes up or down, see Scale operator.

Note that if your packed binary source image is not tiled, this operation takes the source image size as the default tile size, resulting in possibly a big destination tile for a small image after subsampling. An ImageLayout through RenderingHints can be passed in to save memory usage as follows:

   	// example of using SubsampleBinaryToGray operator
      // src is a RenderedImage

      pb = new ParameterBlock();
      pb.addSource(src);
      pb.add(scaleX);	
      pb.add(scaleY);	
      ImageLayout il = new ImageLayout();
      il.setTileWidth(newTileWidth);
      il.setTileHeight(newTileHeight);
      RenderingHints hints = new RenderingHints(JAI.KEY_IMAGE_LAYOUT, il);
      RenderedImage   dst  = (RenderedImage)JAI.create("subsamplebinarytogray",
  	                                                  pb,  hints);
 

Resource List

Name	Value
GlobalName	SubsampleBinaryToGray
LocalName	SubsampleBinaryToGray
Vendor	com.sun.media.jai
Description	Subsamples a binary image into a gray scale image.
DocURL	http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/SubsampleBinaryToGrayDescriptor.html
Version	1.0
arg0Desc	The X scale factor.
arg1Desc	The Y scale factor.

Parameter List

Name	Class Type	Default Value
xScale	java.lang.Float	1.0F
yScale	java.lang.Float	1.0F

Since:

JAI 1.1

See Also:

OperationDescriptor, Serialized Form

Fields inherited from class javax.media.jai.OperationDescriptorImpl

resources, sourceNames, supportedModes

Constructor Summary

SubsampleBinaryToGrayDescriptor()
Constructor.

Method Summary

Number	getParamMinValue(int index) Returns the minimum legal value of a specified numeric parameter for this operation.
PropertyGenerator[]	getPropertyGenerators() Returns an array of PropertyGenerators implementing property inheritance for the "SubsampleBinaryToGray" operation.
boolean	isRenderableSupported() Returns true since renderable operation is supported.
protected boolean	validateParameters(ParameterBlock args, StringBuffer msg) Validates the input parameters.

Methods inherited from class javax.media.jai.OperationDescriptorImpl

arePropertiesSupported, getDefaultSourceClass, getDestClass, getDestClass, getInvalidRegion, getName, getNumParameters, getNumSources, getParamClasses, getParamDefaults, getParamDefaultValue, getParameterListDescriptor, getParamMaxValue, getParamNames, getPropertyGenerators, getRenderableDestClass, getRenderableSourceClasses, getResourceBundle, getResources, getSourceClasses, getSourceClasses, getSourceNames, getSupportedModes, isImmediate, isModeSupported, isRenderedSupported, makeDefaultSourceClassList, validateArguments, validateArguments, validateParameters, validateRenderableArguments, validateRenderableSources, validateSources, validateSources

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SubsampleBinaryToGrayDescriptor

public SubsampleBinaryToGrayDescriptor()

Constructor.

Method Detail

isRenderableSupported

public boolean isRenderableSupported()

Returns true since renderable operation is supported.

Overrides:

isRenderableSupported in class OperationDescriptorImpl

Tags copied from class: OperationDescriptorImpl

See Also:

OperationDescriptorImpl.isModeSupported(java.lang.String)

getPropertyGenerators

public PropertyGenerator[] getPropertyGenerators()

Returns an array of PropertyGenerators implementing property inheritance for the "SubsampleBinaryToGray" operation.

Overrides:

getPropertyGenerators in class OperationDescriptorImpl

Returns:

An array of property generators.

validateParameters

protected boolean validateParameters(ParameterBlock args,
                                     StringBuffer msg)

Validates the input parameters.

In addition to the standard checks performed by the superclass method, this method checks that "xScale" and "yScale" are both greater than 0 and less than or equal to 1.

The src image must be a binary, a one band, one bit per pixel image with a MultiPixelPackedSampleModel.

Overrides:

validateParameters in class OperationDescriptorImpl

Tags copied from class: OperationDescriptorImpl

Throws:

IllegalArgumentException - if args is null.

IllegalArgumentException - if msg is null and the validation fails.

See Also:

OperationDescriptorImpl.validateParameters(java.lang.String, java.awt.image.renderable.ParameterBlock, java.lang.StringBuffer)

getParamMinValue

public Number getParamMinValue(int index)

Returns the minimum legal value of a specified numeric parameter for this operation.

For the minimum value of "xScale" and "yScale", this method returns 0. However, the scale factors must be a positive floating number and can not be 0.

Overrides:

getParamMinValue in class OperationDescriptorImpl

Tags copied from class: OperationDescriptorImpl

Parameters:

index - The index of the parameter to be queried.

Returns:

A Number representing the minimum legal value, or null if the specified parameter is not numeric.

Throws:

IllegalArgumentException - if this operation has no parameters.

ArrayIndexOutOfBoundsException - if there is no parameter corresponding to the specified index.

See Also:

ParameterListDescriptor.getParamValueRange(java.lang.String), ParameterListDescriptor.getEnumeratedParameterValues(java.lang.String), ParameterListDescriptor.isParameterValueValid(java.lang.String, java.lang.Object)