public static PinnedBitmap Convolute(Bitmap source, double[,] kernel)
{
var kernelHeight = kernel.GetUpperBound(0) + 1;
var kernelWidth = kernel.GetUpperBound(1) + 1;
if ((kernelWidth % 2) == 0 || (kernelHeight % 2) == 0)
{
throw new InvalidOperationException("Invalid kernel size");
}
using (var pinnedSource = PinnedBitmap.FromBitmap(source))
{
var width = source.Width;
var height = source.Height;
var result = new PinnedBitmap(width, height);
var index = 0;
var halfKernelWidth = kernelWidth >> 1;
var halfKernelHeight = kernelHeight >> 1;
for (var y = 0; y < height; y++)
{
for (var x = 0; x < width; x++)
{
var a = 0.0;
var r = 0.0;
var g = 0.0;
var b = 0.0;
for (var kernelX = -halfKernelWidth; kernelX <= halfKernelWidth; kernelX++)
{
var pixelX = kernelX + x;
if (pixelX < 0)
{
pixelX = 0;
}
else if (pixelX >= width)
{
pixelX = width - 1;
}
for (var kernelY = -halfKernelHeight; kernelY <= halfKernelHeight; kernelY++)
{
var pixelY = kernelY + y;
if (pixelY < 0)
{
pixelY = 0;
}
else if (pixelY >= height)
{
pixelY = height - 1;
}
var col = pinnedSource.Data[pixelY * width + pixelX];
var k = kernel[kernelY + halfKernelWidth, kernelX + halfKernelHeight];
a += ((col >> 24) & 0x000000FF) * k;
r += ((col >> 16) & 0x000000FF) * k;
g += ((col >> 8) & 0x000000FF) * k;
b += ((col) & 0x000000FF) * k;
}
}
var alphaInt = (int)a;
var alpha = (byte)((alphaInt > 255) ? 255 : ((alphaInt < 0) ? 0 : alphaInt));
if (alpha == 1)
{
alpha = 0;
}
var redInt = (int)r;
var red = (byte)((redInt > 255) ? 255 : ((redInt < 0) ? 0 : redInt));
var greenInt = (int)g;
var green = (byte)((greenInt > 255) ? 255 : ((greenInt < 0) ? 0 : greenInt));
var blueInt = (int)b;
var blue = (byte)((blueInt > 255) ? 255 : ((blueInt < 0) ? 0 : blueInt));
result.Data[index++] = (alpha << 24) | (red << 16) | (green << 8) | blue;
}
}
return(result);
}
}
