public static Bitmap BlurImage(Bitmap bitmap, float sigma)
{
int range = (int)(1 + sigma * 2f);
float c = 1 / MathF.Sqrt(sigma * sigma * 2 * MathF.PI);
float[] blurMatrix = new float[range];
for (int i = 0; i < range; i++)
{
blurMatrix[i] = MathF.Pow(MathF.E, -(i * i) / (2 * sigma * sigma)) * c;
}
Color[] colors = BitmapConvert.ColorArrayFromBitmap(bitmap);
Color[] colors2 = new Color[colors.Length];
DirectBitmap result = new DirectBitmap(bitmap.Width, bitmap.Height);
int width = bitmap.Width;
int height = bitmap.Height;
Parallel.For(0, bitmap.Width, x => {
for (int y = 0; y < height; y++)
{
float r = 0;
float g = 0;
float b = 0;
for (int i = x - range + 1; i < x + range; i++)
{
if (i < 0 || i >= width)
{
r += colors[x + y * width].R * blurMatrix[Math.Abs(x - i)];
g += colors[x + y * width].G * blurMatrix[Math.Abs(x - i)];
b += colors[x + y * width].B * blurMatrix[Math.Abs(x - i)];
}
else
{
r += colors[i + y * width].R * blurMatrix[Math.Abs(x - i)];
g += colors[i + y * width].G * blurMatrix[Math.Abs(x - i)];
b += colors[i + y * width].B * blurMatrix[Math.Abs(x - i)];
}
}
colors2[x + y * width] = ColorConvertors.ClampRgbToColor((int)r, (int)g, (int)b);
}
});
Parallel.For(0, bitmap.Height, y => {
for (int x = 0; x < width; x++)
{
float r = 0;
float g = 0;
float b = 0;
for (int j = y - range + 1; j < y + range; j++)
{
if (j < 0 || j >= height)
{
r += colors[x + y * width].R * blurMatrix[Math.Abs(y - j)];
g += colors[x + y * width].G * blurMatrix[Math.Abs(y - j)];
b += colors[x + y * width].B * blurMatrix[Math.Abs(y - j)];
}
else
{
r += colors2[x + j * width].R * blurMatrix[Math.Abs(y - j)];
g += colors2[x + j * width].G * blurMatrix[Math.Abs(y - j)];
b += colors2[x + j * width].B * blurMatrix[Math.Abs(y - j)];
}
}
result.SetPixel(x, y, ColorConvertors.ClampRgbToColor((int)r, (int)g, (int)b));
}
});
return(result.Bitmap);
}