RGB HSV HLS三种色彩模式转换（C语言实现）

void RGB2HSV( uint16_t * h, uint16_t * s, uint16_t * v, uint8_t r, uint8_t g, uint8_t b)
{
double rr, gg, bb;
double hh, ss, vv;
double cmax, cmin, cdes;

rr = r;
gg = g;
bb = b;

cmax = (rr > gg) ? rr : gg;
if (bb > cmax) {
cmax = bb;
}

cmin = (rr < gg) ? rr : gg;
if (bb < cmin) {
cmin = bb;
}

cdes = cmax - cmin;
vv = cmax;
if (cdes != 0) {
ss = cdes * SCALE / cmax;
if (cmax == rr) {
hh = (gg - bb) * SCALE / cdes;
}else if (cmax == gg) {
hh = (bb - rr) * SCALE / cdes + 2 * H_SCALE;
}else {
hh = (rr - gg) * SCALE / cdes + 4 * H_SCALE;
}
}else if (cmax != 0) {
ss = cdes * SCALE / cmax;
hh = 0;
}else {
ss = 0;
hh = 0;
}
if (hh < 0) {
hh += 6 * H_SCALE;
}

*h = hh * H_GETA;
*s = ss * H_GETA;
*v = vv * H_GETA;
}

void HSV2RGB( uint8_t *r, uint8_t *g, uint8_t *b, uint16_t h, uint16_t s, uint16_t v)
{
double rr = 0, gg = 0, bb = 0;
double hh, ss, vv;

if (h == 6 * H_GETA * H_SCALE) {
h = 0;
}
hh = (double)h / H_GETA;
ss = (double)s / GETA;
vv = (double)v / GETA;

switch((int)(hh / H_SCALE)) {
case 0:
rr = SCALE;
gg = hh;
bb = 0;
break;
case 1:
rr = 2 * H_SCALE - hh;
gg = SCALE;
bb = 0;
break;
case 2:
rr = 0;
gg = SCALE;
bb = hh - 2 * H_SCALE;
break;
case 3:
rr = 0;
gg = 4 * H_SCALE - hh;
bb = SCALE;
break;
case 4:
rr = hh - 4 * H_SCALE;
gg = 0;
bb = SCALE;
break;
case 5:
rr = SCALE;
gg = 0;
bb = 6 * H_SCALE - hh;
break;
}

rr = (rr + (SCALE - rr) * (SCALE - ss) / SCALE) * vv / SCALE;
gg = (gg + (SCALE - gg) * (SCALE - ss) / SCALE) * vv / SCALE;
bb = (bb + (SCALE - bb) * (SCALE - ss) / SCALE) * vv / SCALE;

*r = rr;
*g = gg;
*b = bb;
if (*r > 255)*r = 255;
if (*g > 255)*g = 255;
if (*b > 255)*b = 255;
}

void RGB2HLS( double *h, double *l, double *s, uint8_t r, uint8_t g, uint8_t b)
{
double dr = (double)r/255;
double dg = (double)g/255;
double db = (double)b/255;
double cmax = MAX(dr, MAX(dg, db));
double cmin = MIN(dr, MIN(dg, db));
double cdes = cmax - cmin;
double hh, ll, ss;

ll = (cmax+cmin)/2;
if(cdes){
if(ll <= 0.5)
ss = (cmax-cmin)/(cmax+cmin);
else
ss = (cmax-cmin)/(2-cmax-cmin);

if(cmax == dr)
hh = (0+(dg-db)/cdes)*60;
else if(cmax == dg)
hh = (2+(db-dr)/cdes)*60;
else// if(cmax == b)
hh = (4+(dr-dg)/cdes)*60;
if(hh<0)
hh+=360;
}else
hh = ss = 0;

*h = hh;
*l = ll;
*s = ss;
}

void HLS2RGB( uint8_t *r, uint8_t *g, uint8_t *b, double h, double l, double s)
{
double cmax,cmin;

if(l <= 0.5)
cmax = l*(1+s);
else
cmax = l*(1-s)+s;
cmin = 2*l-cmax;

if(s == 0){
*r = *g = *b = l*255;
}else{
*r = HLS2RGBvalue(cmin,cmax,h+120)*255;
*g = HLS2RGBvalue(cmin,cmax,h)*255;
*b = HLS2RGBvalue(cmin,cmax,h-120)*255;
}
}

double HLS2RGBvalue(double n1,double n2, double hue)
{
if(hue > 360)
hue -= 360;
else if(hue < 0)
hue += 360;
if(hue < 60)
return n1+(n2-n1)*hue/60;
else if(hue < 180)
return n2;
else if(hue < 240)
return n1+(n2-n1)*(240-hue)/60;
else
return n1;
}