RGB2HSV
从OpenCV的源代码中扣出来的将8位RGB值转换为8位HSV值的代码。
速度还不错，比网上找得几个转换代码都要快。
const unsigned char fast_table[] =
{
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207,
208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255
};
#define FAST_CAST_8U(t) (assert(-256 <= (t) || (t) <= 512), fast_table[(t)+256])
#define CALC_MIN_8U(a,b) (a) -= FAST_CAST_8U((a) - (b))
#define CALC_MAX_8U(a,b) (a) += FAST_CAST_8U((b) - (a))
void RGB2HSV(unsigned char * src, unsigned char * dst)
{
const int hsv_shift = 12;
static const int div_table[] = {
0, 1044480, 522240, 348160, 261120, 208896, 174080, 149211,
130560, 116053, 104448, 94953, 87040, 80345, 74606, 69632,
65280, 61440, 58027, 54973, 52224, 49737, 47476, 45412,
43520, 41779, 40172, 38684, 37303, 36017, 34816, 33693,
32640, 31651, 30720, 29842, 29013, 28229, 27486, 26782,
26112, 25475, 24869, 24290, 23738, 23211, 22706, 22223,
21760, 21316, 20890, 20480, 20086, 19707, 19342, 18991,
18651, 18324, 18008, 17703, 17408, 17123, 16846, 16579,
16320, 16069, 15825, 15589, 15360, 15137, 14921, 14711,
14507, 14308, 14115, 13926, 13743, 13565, 13391, 13221,
13056, 12895, 12738, 12584, 12434, 12288, 12145, 12006,
11869, 11736, 11605, 11478, 11353, 11231, 11111, 10995,
10880, 10768, 10658, 10550, 10445, 10341, 10240, 10141,
10043, 9947, 9854, 9761, 9671, 9582, 9495, 9410,
9326, 9243, 9162, 9082, 9004, 8927, 8852, 8777,
8704, 8632, 8561, 8492, 8423, 8356, 8290, 8224,
8160, 8097, 8034, 7973, 7913, 7853, 7795, 7737,
7680, 7624, 7569, 7514, 7461, 7408, 7355, 7304,
7253, 7203, 7154, 7105, 7057, 7010, 6963, 6917,
6872, 6827, 6782, 6739, 6695, 6653, 6611, 6569,
6528, 6487, 6447, 6408, 6369, 6330, 6292, 6254,
6217, 6180, 6144, 6108, 6073, 6037, 6003, 5968,
5935, 5901, 5868, 5835, 5803, 5771, 5739, 5708,
5677, 5646, 5615, 5585, 5556, 5526, 5497, 5468,
5440, 5412, 5384, 5356, 5329, 5302, 5275, 5249,
5222, 5196, 5171, 5145, 5120, 5095, 5070, 5046,
5022, 4998, 4974, 4950, 4927, 4904, 4881, 4858,
4836, 4813, 4791, 4769, 4748, 4726, 4705, 4684,
4663, 4642, 4622, 4601, 4581, 4561, 4541, 4522,
4502, 4483, 4464, 4445, 4426, 4407, 4389, 4370,
4352, 4334, 4316, 4298, 4281, 4263, 4246, 4229,
4212, 4195, 4178, 4161, 4145, 4128, 4112, 4096
};
int blue_idx = 2;
int b = (src)[blue_idx], g = (src)[1], r = (src)[2^blue_idx];
int h, s, v = b;
int vmin = b, diff;
int vr, vg;
CALC_MAX_8U( v, g );
CALC_MAX_8U( v, r );
CALC_MIN_8U( vmin, g );
CALC_MIN_8U( vmin, r );
diff = v - vmin;
vr = v == r ? -1 : 0;
vg = v == g ? -1 : 0;
s = diff * div_table[v] >> hsv_shift;
h = (vr & (g - b)) +
(~vr & ((vg & (b - r + 2 * diff)) + ((~vg) & (r - g + 4 * diff))));
h = ((h * div_table[diff] * 15 + (1 << (hsv_shift + 6))) >> (7 + hsv_shift))\
+ (h < 0 ? 30*6 : 0);
dst[0] = (uchar)h;
dst[1] = (uchar)s;
dst[2] = (uchar)v;
return;
}
