/// <summary>
/// see: http://stackoverflow.com/questions/3018313/algorithm-to-convert-rgb-to-hsv-and-hsv-to-rgb
/// and: http://www.cbusforums.com/forums/showthread.php?t=8657
/// range for HSV is H:[0-180], S:[0-255], V:[0-255]
/// </summary>
public unsafe static void ConvertHsvToBgr_Byte(IImage src, IImage dest)
{
Hsv8 *srcPtr = (Hsv8 *)src.ImageData;
Bgr8 *dstPtr = (Bgr8 *)dest.ImageData;
int width = src.Width;
int height = src.Height;
int srcShift = src.Stride - width * sizeof(Hsv8); //DO NOT divide with sizeof(Bgr8) as reminder may not be 0!!!
int dstShift = dest.Stride - width * sizeof(Bgr8);
for (int row = 0; row < height; row++)
{
for (int col = 0; col < width; col++)
{
Hsv8.ConvertHsvToBgr(srcPtr, dstPtr);
srcPtr++;
dstPtr++;
}
srcPtr = (Hsv8 *)((byte *)srcPtr + srcShift);
dstPtr = (Bgr8 *)((byte *)dstPtr + dstShift);
}
}
public unsafe static void ConvertHsvToBgr(Hsv8 *hsv, Bgr8 *bgr)
{
if (hsv->S == 0)
{
bgr->R = hsv->V;
bgr->G = hsv->V;
bgr->B = hsv->V;
return;
}
int hue = hsv->H * 2; //move to [0-360 range] (only needed for byte!)
int hQuadrant = hue / 60; // Hue quadrant 0 - 5 (60deg)
int hOffset = hue % 60; // Hue position in quadrant
int vs = hsv->V * hsv->S;
byte p = (byte)(hsv->V - (vs / 255));
byte q = (byte)(hsv->V - (vs / 255 * hOffset) / 60);
byte t = (byte)(hsv->V - (vs / 255 * (60 - hOffset)) / 60);
switch (hQuadrant)
{
case 0:
bgr->R = hsv->V; bgr->G = t; bgr->B = p;
break;
case 1:
bgr->R = q; bgr->G = hsv->V; bgr->B = p;
break;
case 2:
bgr->R = p; bgr->G = hsv->V; bgr->B = t;
break;
case 3:
bgr->R = p; bgr->G = q; bgr->B = hsv->V;
break;
case 4:
bgr->R = t; bgr->G = p; bgr->B = hsv->V;
break;
default:
bgr->R = hsv->V; bgr->G = p; bgr->B = q;
break;
}
}
private unsafe static void convertBgrToHsv_Byte(Bgr8 *bgr, Hsv8 *hsv)
{
byte rgbMin, rgbMax;
rgbMin = bgr->R < bgr->G ? (bgr->R < bgr->B ? bgr->R : bgr->B) : (bgr->G < bgr->B ? bgr->G : bgr->B);
rgbMax = bgr->R > bgr->G ? (bgr->R > bgr->B ? bgr->R : bgr->B) : (bgr->G > bgr->B ? bgr->G : bgr->B);
hsv->V = rgbMax;
if (hsv->V == 0)
{
hsv->H = 0;
hsv->S = 0;
return;
}
hsv->S = (byte)(255 * (rgbMax - rgbMin) / rgbMax);
if (hsv->S == 0)
{
hsv->H = 0;
return;
}
int hue = 0;
if (rgbMax == bgr->R)
{
hue = 0 + 60 * (bgr->G - bgr->B) / (rgbMax - rgbMin);
if (hue < 0)
{
hue += 360;
}
}
else if (rgbMax == bgr->G)
{
hue = 120 + 60 * (bgr->B - bgr->R) / (rgbMax - rgbMin);
}
else //rgbMax == bgr->B
{
hue = 240 + 60 * (bgr->R - bgr->G) / (rgbMax - rgbMin);
}
hsv->H = (byte)(hue / 2); //scale [0-360] -> [0-180] (only needed for byte!)
Debug.Assert(hue >= 0 && hue <= 360);
}