void IrisBitmap::BitmapRGBtoHSL(const COLOR_RGB *rgb, COLOR_HSL *hsl)
{
float h=0, s=0, l=0;
// normalizes red-green-blue values
float r = rgb->red/255.f;
float g = rgb->green/255.f;
float b = rgb->blue/255.f;
float maxVal = max3v(r, g, b);
float minVal = min3v(r, g, b);
// hue
if(maxVal == minVal)
{
h = 0; // undefined
}
else if(maxVal==r && g>=b)
{
h = 60.0f*(g-b)/(maxVal-minVal);
}
else if(maxVal==r && g<b)
{
h = 60.0f*(g-b)/(maxVal-minVal) + 360.0f;
}
else if(maxVal==g)
{
h = 60.0f*(b-r)/(maxVal-minVal) + 120.0f;
}
else if(maxVal==b)
{
h = 60.0f*(r-g)/(maxVal-minVal) + 240.0f;
}
// luminance
l = (maxVal+minVal)/2.0f;
// saturation
if(l == 0 || maxVal == minVal)
{
s = 0;
}
else if(0<l && l<=0.5f)
{
s = (maxVal-minVal)/(maxVal+minVal);
}
else if(l>0.5f)
{
s = (maxVal-minVal)/(2 - (maxVal+minVal)); //(maxVal-minVal > 0)?
}
hsl->hue = (h>360)? 360 : ((h<0)?0:h);
hsl->saturation = ((s>1)? 1 : ((s<0)?0:s))*100;
hsl->luminance = ((l>1)? 1 : ((l<0)?0:l))*100;
}
//RGB转HSL
static void RGBtoHSL(const COLOR_RGB *Rgb, COLOR_HSL *Hsl)
{
int h,s,l,maxVal,minVal,difVal;
int r = Rgb->red;
int g = Rgb->green;
int b = Rgb->blue;
maxVal = max3v(r, g, b);
minVal = min3v(r, g, b);
difVal = maxVal-minVal;
//计算亮度
l = (maxVal+minVal)*240/255/2;
if(maxVal == minVal)//若r=g=b
{
h = 0;
s = 0;
}
else
{
//计算色调
if(maxVal==r)
{
if(g>=b)
h = 40*(g-b)/(difVal);
else
h = 40*(g-b)/(difVal) + 240;
}
else if(maxVal==g)
h = 40*(b-r)/(difVal) + 80;
else if(maxVal==b)
h = 40*(r-g)/(difVal) + 160;
//计算饱和度
if(l == 0)
s = 0;
else if(l<=120)
s = (difVal)*240/(maxVal+minVal);
else
s = (difVal)*240/(511 - (maxVal+minVal));
}
Hsl->hue = (unsigned char)(((h>240)? 240 : ((h<0)?0:h)));
Hsl->saturation = (unsigned char)(((s>240)? 240 : ((s<0)?0:s)));
Hsl->luminance = (unsigned char)(((l>240)? 240 : ((l<0)?0:l)));
}