javax.media.jai.operator
Class HistogramDescriptor
java.lang.Object
|
+--javax.media.jai.OperationDescriptorImpl
|
+--javax.media.jai.operator.HistogramDescriptor
- All Implemented Interfaces:
- OperationDescriptor, RegistryElementDescriptor, Serializable
- public class HistogramDescriptor
- extends OperationDescriptorImpl
This OperationDescriptor defines the "Histogram"
operation.
A histogram of an image is represented by a list of "bins"
where each bin is the total number of pixel samples of the image
whose values lie within a given range. This data are encapulated
in the javax.media.jai.Histogram object, and may be
retrieved by calling the getProperty method on this
operator with "histogram" as the property name.
At a request for the histogram property, this operator scans
the specific region of the source image, generates the pixel count
data, and returns an instance of the Histogram class
where the data are stored. The source image's pixels are unchanged
by this operator.
The region-of-interest (ROI), within which the pixels are counted,
does not have to be a rectangle. It may be null, in
which case the entire image is scanned to accumulate the histogram.
The set of pixels scanned may be further reduced by specifying
the "xPeriod" and "yPeriod" parameters that represent the sampling
rate along the two axis. These variables may not be less than 1.
If they are not set, the default value of 1 is used so that every
pixel within the ROI is counted.
The three arguments, numBins, lowValue,
and highValue, define the type of the histogram to be
generated. Please see the Histogram specification for
their detailed descriptions. The three arrays must either have an
array length of 1, in which case the same value is applied to all
bands of the source image, or an array length that equals to the
number of bands of the source image, in which case each value is
applied to its corresponding band. The numBins must
all be greater than 0, and each lowValue must be less
than its corresponding highValue. Note that the default
values of these three parameters are specific to the case wherein
the image data are of type byte. For other image data
types the values of these parameters should be supplied explicitely.
Resource List
| Name | Value |
|---|
| GlobalName | Histogram |
| LocalName | Histogram |
| Vendor | com.sun.media.jai |
| Description | Generates a histogram based on the pixel values
within a specific region of an image. |
| DocURL | http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/HistogramDescriptor.html |
| Version | 1.1 |
| arg0Desc | The region of the image to be scanned. |
| arg1Desc | The horizontal sampling rate;
may not be less than 1. |
| arg2Desc | The vertical sampling rate;
may not be less than 1. |
| arg3Desc | The number of bins for each band. |
| arg4Desc | The lowest inclusive pixel value to be
checked for each band. |
| arg5Desc | The highest exclusive pixel value to be
checked for each band. |
Parameter List
| Name | Class Type |
Default Value |
|---|
| roi | javax.media.jai.ROI |
null |
| xPeriod | java.lang.Integer |
1 |
| yPeriod | java.lang.Integer |
1 |
| numBins | int[] |
{256} |
| lowValue | double[] |
{0.0} |
| highValue | double[] |
{256.0} |
- See Also:
Histogram,
ROI,
OperationDescriptor, Serialized Form
| Methods inherited from class javax.media.jai.OperationDescriptorImpl |
arePropertiesSupported,
getDefaultSourceClass,
getDestClass,
getDestClass,
getInvalidRegion,
getName,
getNumParameters,
getNumSources,
getParamClasses,
getParamDefaults,
getParamDefaultValue,
getParameterListDescriptor,
getParamMaxValue,
getParamNames,
getPropertyGenerators,
getPropertyGenerators,
getRenderableDestClass,
getRenderableSourceClasses,
getResourceBundle,
getResources,
getSourceClasses,
getSourceClasses,
getSourceNames,
getSupportedModes,
isImmediate,
isModeSupported,
isRenderableSupported,
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 |
HistogramDescriptor
public HistogramDescriptor()
- Constructor.
getParamMinValue
public Number getParamMinValue(int index)
- Returns the minimum legal value of a specified numeric parameter
for this operation.
- 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)
validateParameters
protected boolean validateParameters(ParameterBlock args,
StringBuffer msg)
- Returns
true if this operation is capable of handling
the input parameters.
In addition to the default validations done in the super class,
this method verifies that each element of numBins is
greater than 0, and each lowValue is less than its
corresponding highValue.
- Overrides:
- validateParameters in class OperationDescriptorImpl
- Throws:
- IllegalArgumentException - If
args is null.- IllegalArgumentException - If
msg is null
and the validation fails.