public static void convolve(Kernel2D_F64 kernel, GrayF64 input, GrayF64 output) {
final double[] dataSrc = input.data;
final double[] dataDst = output.data;
final double[] dataKer = kernel.data;
final int kernelWidth = kernel.getWidth();
final int offsetL = kernel.getOffset();
final int offsetR = kernelWidth - offsetL - 1;
final int width = input.getWidth();
final int height = input.getHeight();
// convolve across the left and right borders
for (int y = 0; y < height; y++) {
int minI = y >= offsetL ? -offsetL : -y;
int maxI = y < height - offsetR ? offsetR : height - y - 1;
int indexDst = output.startIndex + y * output.stride;
for (int x = 0; x < offsetL; x++) {
double total = 0;
double weight = 0;
for (int i = minI; i <= maxI; i++) {
int indexSrc = input.startIndex + (y + i) * input.stride + x;
int indexKer = (i + offsetL) * kernelWidth;
for (int j = -x; j <= offsetR; j++) {
double w = dataKer[indexKer + j + offsetL];
weight += w;
total += (dataSrc[indexSrc + j]) * w;
}
}
dataDst[indexDst++] = (total / weight);
}
indexDst = output.startIndex + y * output.stride + width - offsetR;
for (int x = width - offsetR; x < width; x++) {
int maxJ = width - x - 1;
double total = 0;
double weight = 0;
for (int i = minI; i <= maxI; i++) {
int indexSrc = input.startIndex + (y + i) * input.stride + x;
int indexKer = (i + offsetL) * kernelWidth;
for (int j = -offsetL; j <= maxJ; j++) {
double w = dataKer[indexKer + j + offsetL];
weight += w;
total += (dataSrc[indexSrc + j]) * w;
}
}
dataDst[indexDst++] = (total / weight);
}
}
// convolve across the top border while avoiding convolving the corners again
for (int y = 0; y < offsetL; y++) {
int indexDst = output.startIndex + y * output.stride + offsetL;
for (int x = offsetL; x < width - offsetR; x++) {
double total = 0;
double weight = 0;
for (int i = -y; i <= offsetR; i++) {
int indexSrc = input.startIndex + (y + i) * input.stride + x;
int indexKer = (i + offsetL) * kernelWidth;
for (int j = -offsetL; j <= offsetR; j++) {
double w = dataKer[indexKer + j + offsetL];
weight += w;
total += (dataSrc[indexSrc + j]) * w;
}
}
dataDst[indexDst++] = (total / weight);
}
}
// convolve across the bottom border
for (int y = height - offsetR; y < height; y++) {
int maxI = height - y - 1;
int indexDst = output.startIndex + y * output.stride + offsetL;
for (int x = offsetL; x < width - offsetR; x++) {
double total = 0;
double weight = 0;
for (int i = -offsetL; i <= maxI; i++) {
int indexSrc = input.startIndex + (y + i) * input.stride + x;
int indexKer = (i + offsetL) * kernelWidth;
for (int j = -offsetL; j <= offsetR; j++) {
double w = dataKer[indexKer + j + offsetL];
weight += w;
total += (dataSrc[indexSrc + j]) * w;
}
}
dataDst[indexDst++] = (total / weight);
}
}
}
