Java Reference
In-Depth Information
ConvolveOp lets you perform spatial convolutions (combining source pixel
and neighbor pixel colors/samples) such as blurring and sharpening.
LookupOp lets you modify pixel component values through lookup tables.
RescaleOp multipliespixelcomponentvaluesbyascalefactorandthenadds
(although lookup tables can be used for this purpose as well).
Caution LookupOp 's Java documentation for its WritableRaster fil-
ter(Raster src, WritableRaster dst) method states that a new raster
is created when you pass null to dst . However, passing null to dst causes
java.lang.NullPointerException to be thrown instead.
Convolving Images
ConvolveOp combines fractions of a source pixel's alpha (when present) and color
components with fractions of its immediate neighbor pixels' components to produce a
destination pixel. The percentage of each pixel's component values to combine is ob-
tainedfromatableoffloating-pointvalues,whichisknownasa kernel .Acomponent's
values are multiplied by the corresponding kernel value and the results are summed.
opaque) maximum.
ConvolveOp moves the kernel across the image to convolve each pixel. The ker-
volved, whereas the other values apply to the neighboring pixels.
The identity kernel hasallvaluessetto0.0exceptforthecentervalue,whichissetto
component values by 1.0 doesn't change these components, and multiplying neighbor
ded to the multiplication results.
Kernelsarerepresentedbyinstancesofthe java.awt.image.Kernel class.To
create a kernel, first create an array of floating-point percentage values, and then pass
to the Kernel(int width, int height, float[] data) constructor.
The following example shows you how to create an identity-based kernel:
float[] identityKernel =
0.0f, 0.0f, 0.0f,
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