Java Doc for MlibConvolveOpImage.java in  » 6.0-JDK-Modules » Java-Advanced-Imaging » com » sun » media » jai » mlib » Java Source Code / Java DocumentationJava Source Code and Java Documentation

This class implements a convolution operation. Convolution is a spatial operation that computes each output sample by multiplying elements of a kernel with the samples surrounding a particular source sample.

For each destination sample, the kernel is rotated 180 degrees and its "key element" is placed over the source pixel corresponding with the destination pixel. The kernel elements are multiplied with the source pixels under them, and the resulting products are summed together to produce the destination sample value.

Example code for the convolution operation on a single sample dst[x][y] is as follows, assuming the kernel is of size M rows x N columns and has already been rotated through 180 degrees. The kernel's key element is located at position (xKey, yKey):

 dst[x][y] = 0;
 for (int i = -xKey; i < M - xKey; i++) {
 for (int j = -yKey; j < N - yKey; j++) {
 dst[x][y] += src[x + i][y + j] * kernel[xKey + i][yKey + j];
 }
 }
 

Convolution, or any neighborhood operation, leaves a band of pixels around the edges undefined, i.e., for a 3x3 kernel, only four kernel elements and four source pixels contribute to the destination pixel located at (0,0). Such pixels are not includined in the destination image, unless a non-null BorderExtender is provided.

The Kernel cannot be bigger in any dimension than the image data.
See Also:   KernelJAI