/// <summary>
/// Converts 8-bit Hsv color to the 8-bit Bgr color.
/// </summary>
public unsafe Bgr8 ToBgr()
{
Hsv8 hsv = this; Bgr8 bgr;
ConvertHsvToBgr(&hsv, &bgr);
return(bgr);
}
private static unsafe 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);
}
/// <summary>
/// Draws lines in various colors regarding their angle.
/// </summary>
/// <param name="image">Input image.</param>
/// <param name="lines">Line segments (treated as vectors)</param>
/// <param name="thickness">Line thickness.</param>
public static void Draw <TColor>(this Image <TColor, byte> image, IEnumerable <LineSegment> lines, float thickness)
where TColor : IColor3
{
Func <LineSegment, Bgr> colorFunc = (segment) =>
{
/************** calculate angle ************/
var diff = segment.End - segment.Start;
var angle = System.Math.Atan2(diff.Y, diff.X);
angle = angle * 180 / System.Math.PI; //to degrees
angle = (angle < 0) ? angle + 360 : angle;
/************** calculate angle ************/
Hsv8 hsv = new Hsv8 {
H = (byte)(angle / 2), S = Byte.MaxValue / 2, V = Byte.MaxValue / 2
};
return(hsv.ToBgr());
};
Draw(image, lines, thickness, colorFunc);
}
public static unsafe 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;
}
}