/// <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 RGB2YCbCr(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 YCbCr2RGB(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>
/// Gather statistics about specified image
/// </summary>
///
/// <param name="imageData">Image data</param>
///
private void ProcessImage(BitmapData imageData)
{
// get image dimension
int width = imageData.Width;
int height = imageData.Height;
pixels = pixelsWithoutBlack = 0;
int[] yhisto = new int[256];
int[] cbhisto = new int[256];
int[] crhisto = new int[256];
int[] yhistoWB = new int[256];
int[] cbhistoWB = new int[256];
int[] crhistoWB = new int[256];
RGB rgb = new RGB( );
YCbCr ycbcr = new YCbCr( );
int offset = imageData.Stride - width * 3;
// do the job
unsafe
{
byte *p = (byte *)imageData.Scan0.ToPointer( );
// for each line
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, p += 3)
{
rgb.Red = p[RGB.R];
rgb.Green = p[RGB.G];
rgb.Blue = p[RGB.B];
// convert to YCbCr color space
BaseControls.ImageBox.Imaging.ColorConverter.RGB2YCbCr(rgb, ycbcr);
yhisto [(int)(ycbcr.Y * 255)]++;
cbhisto[(int)((ycbcr.Cb + 0.5) * 255)]++;
crhisto[(int)((ycbcr.Cr + 0.5) * 255)]++;
pixels++;
if ((ycbcr.Y != 0.0) || (ycbcr.Cb != 0.0) || (ycbcr.Cr != 0.0))
{
yhistoWB [(int)(ycbcr.Y * 255)]++;
cbhistoWB[(int)((ycbcr.Cb + 0.5) * 255)]++;
crhistoWB[(int)((ycbcr.Cr + 0.5) * 255)]++;
pixelsWithoutBlack++;
}
}
p += offset;
}
}
// create histograms
yHistogram = new ContinuousHistogram(yhisto, new DoubleRange(0.0, 1.0));
cbHistogram = new ContinuousHistogram(cbhisto, new DoubleRange(-0.5, 0.5));
crHistogram = new ContinuousHistogram(crhisto, new DoubleRange(-0.5, 0.5));
yHistogramWithoutBlack = new ContinuousHistogram(yhistoWB, new DoubleRange(0.0, 1.0));
cbHistogramWithoutBlack = new ContinuousHistogram(cbhistoWB, new DoubleRange(-0.5, 0.5));
crHistogramWithoutBlack = new ContinuousHistogram(crhistoWB, new DoubleRange(-0.5, 0.5));
}
