由于自己的一个小程序里要用到颜色空间HSL与RGB的转换,所以呢,到处翻资料,模仿借鉴了一个纯C的HSL与RGB颜色空间的相互转换。因为我需要验证这个2个转换算法的正确性,所以将其HSL的值空间转到了0 ~ 240,RGB的值空间转换到了 0 ~ 255,保持和Windows自带的画图工具的值空间一致,这样可以直接使用Windows画图工具来验证。
当然由于是纯C的关系,我们可以直接到Linux下编译运行!!!
算法一(理论算法):
运行截图:
源代码:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/*********************************
*Author: wangli
*E-mail: wanglilife@163.com
*Build Data: 2009-10-08
********************************/
#include
#define max(a,b,c) ((a > ((b>c)?b:c)) ? a : ((b>c)?b:c))
#define min(a,b,c) ((a < ((b
double Hue_2_RGB (double v1, double v2, double vH);
void RGBtoHSL (double r, double g, double b, double* h, double* s, double* l);
void HSLtoRGB (double h, double s, double l, double* R, double* G, double* B);
int main (int argc, char* argv[])
{
double r, g, b;
double h, s, l;
r = 171;
g = 36;
b = 210;
printf ("R = %f, G = %f, B = %f\n", r, g, b);
printf ("Covert RGB to HSL : \n");
RGBtoHSL (r, g, b, &h, &s, &l);
printf ("H = %f, S = %f, L = %f\n\n", h, s, l);
h = 219;
s = 186;
l = 33;
printf ("H = %f, S = %f, L = %f\n", h, s, l);
printf ("Covert HSL to RGB : \n");
HSLtoRGB (h, s, l, &r, &g, &b);
printf ("R = %f, G = %f, B = %f\n\n", r, g, b);
return 0;
}
//RGB from 0 to 255; HSL results from 0 to 240
void RGBtoHSL (double r, double g, double b, double* h, double* s, double* l)
{
//转到RGB(1, 1, 1)的空间
double var_R = r/255;
double var_G = g/255;
double var_B = b/255;
double vmin = min(var_R, var_G, var_B);
double vmax = max(var_R, var_G, var_B);
double delta = vmax - vmin;
double dr, dg, db;
*l = (vmax+vmin) / 2;
if (0 == delta)
{
*h = 0;
*s = 0;
}
else
{
if (*l < 0.5)
*s = delta / (vmax+vmin);
else
*s = delta / (2-vmax-vmin);
dr = (((vmax-var_R)/6) + (delta/2))/delta;
dg = (((vmax-var_G)/6) + (delta/2))/delta;
db = (((vmax-var_B)/6) + (delta/2))/delta;
if (var_R == vmax)
*h = db - dg;
else if (var_G == vmax)
*h = (1.0/3.0) + dr - db;
else if (var_B == vmax)
*h = (2.0/3.0) + dg - dr;
if (*h < 0)
*h += 1;
if (*h > 1)
*h -= 1;
}
//转回到HSL(240, 240, 240)的空间
*h *= 240;
*s *= 240;
*l *= 240;
}
double Hue_2_RGB (double v1, double v2, double vH)
{
if (vH < 0)
vH += 1;
if (vH > 1)
vH -= 1;
if ((6*vH) < 1)
return (v1 + (v2-v1)*6*vH);
if ((2*vH) < 1)
return v2;
if ((3*vH) < 2)
return (v1 + (v2-v1)*((2.0/3.0)-vH)*6);
return v1;
}
//HSL from 0 to 240; RGB results from 0 to 255
void HSLtoRGB (double h, double s, double l, double* R, double* G, double* B)
{
double v1, v2;
//转到HSL(1, 1, 1)的空间
double H = h/240;
double S = s/240;
double L = l/240;
if (0 == S)
{
//转回到RGB(255, 255, 255)的空间
*R = L * 255;
*G = L * 255;
*B = L * 255;
}
else
{
if (L < 0.5)
v2 = L * (1+S);
else
v2 = (L+S) - (L*S);
v1 = 2 * L - v2;
//转回到RGB(255, 255, 255)的空间
*R = 255 * Hue_2_RGB (v1, v2, H+(1.0/3.0));
*G = 255 * Hue_2_RGB (v1, v2, H);
*B = 255 * Hue_2_RGB (v1, v2, H-(1.0/3.0));
}
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
补充语:
1、我这里没有使用从终端输入浮点数,主要是因为使用scanf()函数的获取数据的时候浮点数不能正确得到,所以干脆直接在程序里填制,在验证的时候直接修改程序里的值再编译运行看结果!
2、在变换中为了使精度较高,大多变量都是用了double类型。当然我们在各种作图工具或者调色工具中,很少有可以调节到小数点这个精度的,所以我们在对精度不高的情况下可以对上面的数据类型稍作调整,一个char类型(8bits)就足够了。这个算法不是唯一的变换算法,也不是一定要达到这个精度,我们甚者可以和原来精度有一个比较大的差距(这得看实际应用了)。
3、在维基百科里面 %E5%92%8CHSV%E8%89%B2%E5%BD%A9%E7%A9%BA%E9%97%B4 ,这里后面出现的几组对比值中有一个好像错了。验证时需注意!!!
算法二(Windows算法):
运行截图:
源代码:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/*********************************
*Author: wangli
*E-mail: wanglilife@163.com
*Build Data: 2009-10-08
********************************/
#include
typedef unsigned char BYTE; //0 ~ 2^8 - 1
typedef unsigned short WORD; //0 ~ 2^16 - 1
typedef unsigned long DWORD; //0 ~ 2^32 - 1
#define HSLMAX 240
#define RGBMAX 255
#define UNDEFINED (HSLMAX*2/3)
#define max(a,b,c) ((a > ((b>c)?b:c)) ? a : ((b>c)?b:c))
#define min(a,b,c) ((a < ((b
void RGBtoHSL (WORD r, WORD g, WORD b, WORD* h, WORD* s, WORD* l);
WORD HueToRGB (WORD n1, WORD n2, WORD hue);
void HSLtoRGB (WORD h, WORD s, WORD l, WORD* r, WORD* g, WORD* b);
int main (int argc, char* argv[])
{
WORD r, g, b;
WORD h, s, l;
r = 1;
g = 255;
b = 120;
printf ("R = %d, G = %d, B = %d\n", r, g, b);
printf ("Covert RGB to HSL : \n");
RGBtoHSL (r, g, b, &h, &s, &l);
printf ("H = %d, S = %d, L = %d\n\n", h, s, l);
h = 239;
s = 189;
l = 1;
printf ("H = %d, S = %d, L = %d\n", h, s, l);
printf ("Covert HSL to RGB : \n");
HSLtoRGB (h, s, l, &r, &g, &b);
printf ("R = %d, G = %d, B = %d\n\n", r, g, b);
return 0;
}
void RGBtoHSL (WORD r, WORD g, WORD b, WORD* h, WORD* s, WORD* l)
{
BYTE cMax, cMin;
WORD Rdelta, Gdelta, Bdelta;
cMax = max(r, g, b);
cMin = min(r, g, b);
*l = (((cMax+cMin)*HSLMAX)+RGBMAX) / (2*RGBMAX);
if (cMax == cMin)
{
*s = 0;
*h = UNDEFINED;
}
else
{
if (*l <= (HSLMAX/2))
*s = (((cMax-cMin)*HSLMAX)+((cMax+cMin)/2)) / (cMax+cMin);
else
*s = (((cMax-cMin)*HSLMAX)+((2*RGBMAX-cMax-cMin)/2)) / (2*RGBMAX-cMax-cMin);
Rdelta = (((cMax-r)*(HSLMAX/6))+((cMax-cMin)/2)) / (cMax-cMin);
Gdelta = (((cMax-g)*(HSLMAX/6))+((cMax-cMin)/2)) / (cMax-cMin);
Bdelta = (((cMax-b)*(HSLMAX/6))+((cMax-cMin)/2)) / (cMax-cMin);
if (r == cMax)
*h = Bdelta - Gdelta;
else if (g == cMax)
*h = (HSLMAX/3) + Rdelta - Bdelta;
else
*h = ((2*HSLMAX)/3) + Gdelta - Rdelta;
if (*h < 0)
*h += HSLMAX;
if (*h > HSLMAX)
*h -= HSLMAX;
}
}
//utility routine for HLStoRGB
WORD HueToRGB (WORD n1, WORD n2, WORD hue)
{
if (hue < 0)
hue += HSLMAX;
if (hue > HSLMAX)
hue -= HSLMAX;
if (hue < (HSLMAX/6))
return (n1 + (((n2-n1)*hue+(HSLMAX/12))/(HSLMAX/6)));
if (hue < (HSLMAX/2))
return (n2);
if (hue < ((HSLMAX*2)/3))
return (n1 + (((n2-n1)*(((HSLMAX*2)/3)-hue)+(HSLMAX/12))/(HSLMAX/6)));
else
return (n1);
}
void HSLtoRGB (WORD h, WORD s, WORD l, WORD* r, WORD* g, WORD* b)
{
WORD Magic1, Magic2;
if (0 == s)
{
*r = *g = *b = (l*RGBMAX) / HSLMAX;
if (h != UNDEFINED)
/*error*/;
}
else
{
if (l <= (HSLMAX/2))
Magic2 = (l*(HSLMAX+s)+(HSLMAX/2)) / HSLMAX;
else
Magic2 = l + s - ((l*s)+(HSLMAX/2))/HSLMAX;
Magic1 = 2*l - Magic2;
*r = (HueToRGB(Magic1, Magic2, h+(HSLMAX/3))*RGBMAX+(HSLMAX/2)) / HSLMAX;
*g = (HueToRGB(Magic1, Magic2, h)*RGBMAX+(HSLMAX/2)) / HSLMAX;
*b = (HueToRGB(Magic1, Magic2, h-(HSLMAX/3))*RGBMAX+(HSLMAX/2)) / HSLMAX;
}
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
补充语:
1、这个本来是在MS官方网站上找到的算法,不过对其进行了些许修改,使之成为纯C环境下的代码,应该可以移植到Linux下,我没试过。不过这个是Windows自己的计算方法,Linux下一般都是HSV颜色空间,需要的话自己写代码去,或者参考GIMP等画图软件的源码;
2、官方算法,和Windows画图程序中使用的一模一样,而且RGB值范围为0 ~ 255的整形数,HSL值范围为 0 ~ 240的整形数,非常完美的匹配!
转自:http://wanglilife.blog.163.com/blog/static/464852712009982333791/
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