// Convert from HSL to RGB color space
public static void HSL2RGB(HSL hsl, RGB rgb)
{
if (hsl.Saturation == 0)
{
// gray values
rgb.Red = rgb.Green = rgb.Blue = (byte)(hsl.Luminance * 255);
}
else
{
double v1, v2;
double hue = (double)hsl.Hue / 360;
v2 = (hsl.Luminance < 0.5) ?
(hsl.Luminance * (1 + hsl.Saturation)) :
((hsl.Luminance + hsl.Saturation) - (hsl.Luminance * hsl.Saturation));
v1 = 2 * hsl.Luminance - v2;
rgb.Red = (byte)(255 * Hue_2_RGB(v1, v2, hue + (1.0 / 3)));
rgb.Green = (byte)(255 * Hue_2_RGB(v1, v2, hue));
rgb.Blue = (byte)(255 * Hue_2_RGB(v1, v2, hue - (1.0 / 3)));
}
}
// Process the filter
private unsafe void ProcessFilter(BitmapData data)
{
int width = data.Width;
int height = data.Height;
RGB rgb = new RGB( );
HSL hsl = new HSL( );
int offset = data.Stride - width * 3;
// do the job
byte *ptr = (byte *)data.Scan0.ToPointer( );
// for each row
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, ptr += 3)
{
rgb.Red = ptr[RGB.R];
rgb.Green = ptr[RGB.G];
rgb.Blue = ptr[RGB.B];
// convert to HSL
ColorConverter.RGB2HSL(rgb, hsl);
// modify Hue value
hsl.Hue = hue;
// convert back to RGB
ColorConverter.HSL2RGB(hsl, rgb);
ptr[RGB.R] = rgb.Red;
ptr[RGB.G] = rgb.Green;
ptr[RGB.B] = rgb.Blue;
}
ptr += offset;
}
}
