/// <summary>
/// Convert from RGB to YCbCr color space (Rec 601-1 specification).
/// </summary>
///
/// <param name="rgb">Source color in <b>RGB</b> color space.</param>
/// <param name="ycbcr">Destination color in <b>YCbCr</b> color space.</param>
///
public static void FromRGB(RGB rgb, YCbCr ycbcr)
{
double r = (double)rgb.Red / 255;
double g = (double)rgb.Green / 255;
double b = (double)rgb.Blue / 255;
ycbcr.Y = 0.2989 * r + 0.5866 * g + 0.1145 * b;
ycbcr.Cb = -0.1687 * r - 0.3313 * g + 0.5000 * b;
ycbcr.Cr = 0.5000 * r - 0.4184 * g - 0.0816 * b;
}
/// <summary>
/// Convert from YCbCr to RGB color space.
/// </summary>
///
/// <param name="ycbcr">Source color in <b>YCbCr</b> color space.</param>
/// <param name="rgb">Destination color in <b>RGB</b> color spacs.</param>
///
public static void ToRGB(YCbCr ycbcr, RGB rgb)
{
// don't warry about zeros. compiler will remove them
double r = Math.Max(0.0, Math.Min(1.0, ycbcr.Y + 0.0000 * ycbcr.Cb + 1.4022 * ycbcr.Cr));
double g = Math.Max(0.0, Math.Min(1.0, ycbcr.Y - 0.3456 * ycbcr.Cb - 0.7145 * ycbcr.Cr));
double b = Math.Max(0.0, Math.Min(1.0, ycbcr.Y + 1.7710 * ycbcr.Cb + 0.0000 * ycbcr.Cr));
rgb.Red = (byte)(r * 255);
rgb.Green = (byte)(g * 255);
rgb.Blue = (byte)(b * 255);
}
/// <summary>
/// Color filtering in YCbCr color space.
/// </summary>
public static unsafe Bitmap YCbCrFilter(Bitmap image, Rectangle rect, DoubleRange Y, DoubleRange Cb, DoubleRange Cr)
{
Bitmap dest = new Bitmap(image.Width, image.Height, PixelFormat.Format8bppIndexed);
BitmapData source = image.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadWrite, image.PixelFormat);
BitmapData destination = dest.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadWrite, dest.PixelFormat);
int startX = rect.Left;
int startY = rect.Top;
int stopX = rect.Right;
int stopY = rect.Bottom;
// get pixel size
int pixelSize = (image.PixelFormat == PixelFormat.Format24bppRgb) ? 3 : 4;
int srcOffset = source.Stride - rect.Width * pixelSize;
int dstOffset = destination.Stride - rect.Width;
RGB rgb = new RGB();
YCbCr ycbcr = new YCbCr();
// do the job
byte *src = (byte *)source.Scan0 + startY * source.Stride + startX * pixelSize;
byte *dst = (byte *)destination.Scan0 + startY * destination.Stride + startX;
// for each row
for (int y = startY; y < stopY; y++)
{
// for each pixel
for (int x = startX; x < stopX; x++, src += pixelSize, dst++)
{
rgb.Red = src[RGB.R];
rgb.Green = src[RGB.G];
rgb.Blue = src[RGB.B];
// convert to YCbCr
ycbcr = YCbCr.FromRGB(rgb);
// check YCbCr values
if (Y.IsInside(ycbcr.Y) & Cb.IsInside(ycbcr.Cb) && Cr.IsInside(ycbcr.Cr))
{
*dst = 0;
}
else
{
*dst = 255;
}
}
src += srcOffset;
dst += dstOffset;
}
int width = image.Width;
int height = image.Height;
int stride = destination.Stride;
// remove upper part
for (int y = 0; y < startY; y++)
{
dst = (byte *)destination.Scan0.ToPointer() + y * stride;
SystemTools.SetUnmanagedMemory(dst, 255, stride);
}
// remove lower part
for (int y = stopY; y < height; y++)
{
dst = (byte *)destination.Scan0.ToPointer() + y * stride;
SystemTools.SetUnmanagedMemory(dst, 255, stride);
}
for (int y = startY; y < stopY; y++)
{
// remove left part
dst = (byte *)destination.Scan0.ToPointer() + y * stride;
SystemTools.SetUnmanagedMemory(dst, 255, startX);
// remove right part
dst += stopX;
SystemTools.SetUnmanagedMemory(dst, 255, stride - stopX);
}
image.UnlockBits(source);
dest.UnlockBits(destination);
return(dest);
}
