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Package org.geotoolkit.coverage.processing.operation

Implementations of operations.

See:
          Description

Class Summary
Absolute Computes the mathematical absolute value of each sample value.
AddConst Adds constants (one for each band) to every sample values of the source coverage.
Convolve Computes each output sample by multiplying elements of a kernel with the samples surrounding a particular source sample.
DivideByConst Divides every sample values of the source coverage by constants (one for each band).
Exp Takes the exponential of the sample values of a coverage.
GradientMagnitude Edge detector which computes the magnitude of the image gradient vector in two orthogonal directions.
Interpolate Specifies the interpolation type to be used to interpolate values for points which fall between grid cells.
Invert Inverts the sample values of a coverage.
Log Takes the natural logarithm of the sample values of a coverage.
MaxFilter For each position of the mask, replaces the center pixel by the maximum of the pixel values covered by the mask.
MedianFilter For each position of the mask, replaces the center pixel by the median of the pixel values covered by the mask.
MinFilter For each position of the mask, replaces the center pixel by the minimum of the pixel values covered by the mask.
MultiplyConst Multiplies every sample values of the source coverage by constants (one for each band).
NodataFilter Replaces NaN values by the weighted average of neighbors values.
Recolor Replaces the colors of a GridCoverage2D.
Resample Resample a grid coverage using a different grid geometry.
Rescale Maps the sample values of a coverage from one range to another range.
SelectSampleDimension Chooses N sample dimensions from a grid coverage and copies their sample data to the destination grid coverage in the order specified.
SubtractConst Subtracts constants (one for each band) from every sample values of the source coverage.
SubtractFromConst Subtracts every sample values of the source coverage from constants (one for each band).
 

Package org.geotoolkit.coverage.processing.operation Description

Implementations of operations. This package is useful for documentation purpose since class names match exactly operation names, and the javadoc for each class provides a table of valid arguments. But the classes provided there should not be used directly. There is no need to instantiate them, since it is already done by the default coverage processor which manage them.

If the operation to apply is know at compile time, then the easiest way to use this package is to use the Operations convenience class. For example a grid coverage can be resampled to a different coordinate reference system using the following code: 

Coverage reprojected = Operations.DEFAULT.resample(myCoverage, newCRS);
If the operation to apply is unknown at compile time (for example because it is selected at runtime by the user in some widget), or if the operation is not listed in the Operations convenience class, then the generic way is to invoke the doOperation method on the default processor instance. Available operations are listed in this package, but the tables below summarize the main ones.

Supported operations

 

 

Convolve

Computes each output sample by multiplying elements of a kernel with the samples surrounding a particular source sample.

Name: "Convolve"
JAI operator: "Convolve"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"kernel" KernelJAI N/A N/A N/A

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LaplaceType1Filter

Perform a laplacian filter operation on a grid coverage. This is a high pass filter which highlights the edges having positive and negative brightness slopes. This filter mulitples the co-efficients in the tabe below with the corresponding grid data value in the kernel window. The new grid value will be calculated as the sum of (grid value * co-efficient) for each kernel cell divised by 9.

0 -1 0
-1 4 -1
0 -1 0

Name: "LaplaceType1Filter"
JAI operator: "Convolve"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A

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LaplaceType2Filter

Perform a laplacian filter operation on a grid coverage. This is a high pass filter which highlights the edges having positive and negative brightness slopes. This filter mulyiplies the co-efficients in the tabe below with the corresponding grid data value in the kernel window. The new grid value will be calculated as the sum of (grid value * co-efficient) for each kernel cell divised by 9.

-1 -1 -1
-1 8 -1
-1 -1 -1

Name: "LaplaceType1Filter"
JAI operator: "Convolve"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A

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MaxFilter

Non-linear filter which is useful for removing isolated lines or pixels while preserving the overall appearance of an image. The filter is implemented by moving a mask over the image. For each position of the mask, the center pixel is replaced by the max of the pixel values covered by the mask. There are several shapes possible for the mask, which are enumerated in the JAI documentation.

Name: "MaxFilter"
JAI operator: "MaxFilter"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"Xsize" Integer 3 1 N/A
"Ysize" Integer 3 1 N/A
"maskShape" MaxFilterShape MaxFilterDescriptor.MAX_MASK_SQUARE N/A N/A

Note: In current implementation, Xsize and Ysize must have the same value (i.e. rectangular shapes are not supported).

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MedianFilter

Non-linear filter which is useful for removing isolated lines or pixels while preserving the overall appearance of an image. The filter is implemented by moving a mask over the image. For each position of the mask, the center pixel is replaced by the median of the pixel values covered by the mask. This filter results in a smoothing of the image values. There are several shapes possible for the mask, which are enumerated in the JAI documentation.

Name: "MedianFilter"
JAI operator: "MedianFilter"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"Xsize" Integer 3 1 N/A
"Ysize" Integer 3 1 N/A
"maskShape" MedianFilterShape MedianFilterDescriptor.MEDIAN_MASK_SQUARE N/A N/A

Note: In current implementation, Xsize and Ysize must have the same value (i.e. rectangular shapes are not supported).

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MinFilter

Non-linear filter which is useful for removing isolated lines or pixels while preserving the overall appearance of an image. The filter is implemented by moving a mask over the image. For each position of the mask, the center pixel is replaced by the min of the pixel values covered by the mask. There are several shapes possible for the mask, which are enumerated in the JAI documentation.

Name: "MinFilter"
JAI operator: "MinFilter"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"Xsize" Integer 3 1 N/A
"Ysize" Integer 3 1 N/A
"maskShape" MinFilterShape MinFilterDescriptor.MIN_MASK_SQUARE N/A N/A

Note: In current implementation, Xsize and Ysize must have the same value (i.e. rectangular shapes are not supported).

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Recolor

Changes the colors associated to arbitrary categories in arbitrary bands. The ColorMaps arguments must be an array of Maps with a minimal length of 1. The Map in array element 0 is used for band 0; the Map in array element 1 is used for band 1, etc. If there is more bands than array elements in ColorMaps, then the last Map is reused for all remaining bands.

For each Map in ColorMaps, the keys are category names as String and the values are colors as an array of type Color[]. All categories with a name matching a key in the Map will be recolored with the associated colors. All categories with no corresponding entries in the Map will be left unchanged. The null key is a special value meaning "any quantitative category". For example in order to repaint forest in green, river in blue and lets other categories unchanged, one can write:

Map map = new HashMap();
map.put("Forest", new Color[]{Color.GREEN});
map.put("River",  new Color[]{Color.BLUE });
Map[] colorMaps = new Map[] {
    map  // Use for all bands
}

Name: "Recolor"
JAI operator: N/A
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"ColorMaps" Map[] A gray scale N/A N/A

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Threshold

A gray scale threshold classifies the grid coverage values into a boolean value. The sample dimensions will be modified into a boolean value and the dimension type of the source sample dimension will be represented as 1 bit.

Name: "Threshold"
JAI operator: "Binarize"
Parameters:

Name Class Default value Minimum value Maximum value
"Source" GridCoverage2D N/A N/A N/A
"threshold" double[] N/A N/A N/A

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Since:
2.1
Version:
3.00
Author:
Martin Desruisseaux (IRD)
Module:
coverage/geotk-coverage (download)
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