如何在C / C ++中将RGB转换为HSL?
(注意:这是一个(简短的)自我答案 - 我在这里发布,所以人们可以通过搜索快速找到它。)
答案 0 :(得分:3)
从here翻译代码,您得到:
// Assuming sizeof(unsigned int) == 4 * sizeof(unsigned char)
unsigned int RgbToHsl(unsigned int rgb) // Alpha value is simply passed through
{
#ifdef __cplusplus
using std::max;
using std::min;
#endif
double
r = (rgb >> (0 * CHAR_BIT)) & UCHAR_MAX,
g = (rgb >> (1 * CHAR_BIT)) & UCHAR_MAX,
b = (rgb >> (2 * CHAR_BIT)) & UCHAR_MAX;
r /= UCHAR_MAX;
g /= UCHAR_MAX;
b /= UCHAR_MAX;
double
maxv = max(max(r, g), b),
minv = min(min(r, g), b),
h = 0, s = 0, d = maxv - minv,
l = (maxv + minv) / 2;
if (maxv != minv)
{
s = l > 0.5 ? d / (2 - maxv - minv) : d / (maxv + minv);
if (maxv == r) { h = (g - b) / d + (g < b ? 6 : 0); }
else if (maxv == g) { h = (b - r) / d + 2; }
else if (maxv == b) { h = (r - g) / d + 4; }
h /= 6;
}
return ((unsigned int)(h * UCHAR_MAX) << (0 * CHAR_BIT)) |
((unsigned int)(s * UCHAR_MAX) << (1 * CHAR_BIT)) |
((unsigned int)(l * UCHAR_MAX) << (2 * CHAR_BIT)) |
(((rgb >> (3 * CHAR_BIT)) & UCHAR_MAX) << (3 * CHAR_BIT));
}
假设顺序是RGBA,其中R是最低有效字节。