projects / imager.git / blame
| Commit | Line | Data |
|---|---|---|
| 6607600c TC |
1 | #include "image.h" |
| 2 | ||
| 3 | /* | |
| 4 | =head1 NAME | |
| 5 | ||
| 6 | color.c - color manipulation functions | |
| 7 | ||
| 8 | =head1 SYNOPSIS | |
| 9 | ||
| 10 | i_fcolor color; | |
| 11 | i_rgb_to_hsvf(&color); | |
| 12 | i_hsv_to_rgbf(&color); | |
| 13 | ||
| 14 | =head1 DESCRIPTION | |
| 15 | ||
| 16 | A collection of utility functions for converting between color spaces. | |
| 17 | ||
| 18 | */ | |
| 19 | ||
| 20 | #define EPSILON (1e-8) | |
| 21 | ||
| 22 | /* | |
| 23 | =item i_rgb2hsvf(&color) | |
| 24 | ||
| 25 | Converts the first 3 channels of color into hue, saturation and value. | |
| 26 | ||
| 27 | Each value is scaled into the range 0 to 1.0. | |
| 28 | ||
| 29 | =cut | |
| 30 | */ | |
| 31 | void i_rgb_to_hsvf(i_fcolor *color) { | |
| 32 | double h, s, v; | |
| 33 | double temp; | |
| 34 | double Cr, Cg, Cb; | |
| 35 | ||
| 36 | v = max(max(color->rgb.r, color->rgb.g), color->rgb.b); | |
| 37 | temp = min(min(color->rgb.r, color->rgb.g), color->rgb.b); | |
| 38 | if (v < EPSILON) | |
| 39 | s = 0; | |
| 40 | else | |
| 41 | s = (v-temp)/v; | |
| 42 | if (s == 0) | |
| 43 | h = 0; | |
| 44 | else { | |
| 45 | Cr = (v - color->rgb.r)/(v-temp); | |
| 46 | Cg = (v - color->rgb.g)/(v-temp); | |
| 47 | Cb = (v - color->rgb.b)/(v-temp); | |
| 48 | if (color->rgb.r == v) | |
| 49 | h = Cb - Cg; | |
| 50 | else if (color->rgb.g == v) | |
| 51 | h = 2 + Cr - Cb; | |
| 52 | else if (color->rgb.b == v) | |
| 53 | h = 4 + Cg - Cr; | |
| 54 | h = 60 * h; | |
| 55 | if (h < 0) | |
| 56 | h += 360; | |
| 57 | } | |
| 58 | color->channel[0] = h / 360.0; | |
| 59 | color->channel[1] = s; | |
| 60 | color->channel[2] = v; | |
| 61 | } | |
| 62 | ||
| 63 | /* | |
| 64 | =item i_hsv_to_rgbf(&color) | |
| 65 | ||
| 66 | Convert a HSV value to an RGB value, each value ranges from 0 to 1. | |
| 67 | ||
| 68 | =cut | |
| 69 | */ | |
| 70 | ||
| 71 | void i_hsv_to_rgbf(i_fcolor *color) { | |
| 72 | double h = color->channel[0]; | |
| 73 | double s = color->channel[1]; | |
| 74 | double v = color->channel[2]; | |
| 75 | ||
| 76 | if (color->channel[1] < EPSILON) { | |
| 77 | /* ignore h in this case */ | |
| 78 | color->rgb.r = color->rgb.g = color->rgb.b = v; | |
| 79 | } | |
| 80 | else { | |
| 81 | int i; | |
| 82 | double f, m, n, k; | |
| 83 | h = fmod(h, 1.0) * 6; | |
| 84 | i = h; | |
| 85 | f = h - i; | |
| 86 | m = v * (1 - s); | |
| 87 | n = v * (1 - s * f); | |
| 88 | k = v * (1 - s * (1 - f)); | |
| 89 | switch (i) { | |
| 90 | case 0: | |
| 91 | color->rgb.r = v; color->rgb.g = k; color->rgb.b = m; | |
| 92 | break; | |
| 93 | case 1: | |
| 94 | color->rgb.r = n; color->rgb.g = v; color->rgb.b = m; | |
| 95 | break; | |
| 96 | case 2: | |
| 97 | color->rgb.r = m; color->rgb.g = v; color->rgb.b = k; | |
| 98 | break; | |
| 99 | case 3: | |
| 100 | color->rgb.r = m; color->rgb.g = n; color->rgb.b = v; | |
| 101 | break; | |
| 102 | case 4: | |
| 103 | color->rgb.r = k; color->rgb.g = m; color->rgb.b = v; | |
| 104 | break; | |
| 105 | case 5: | |
| 106 | color->rgb.r = v; color->rgb.g = m; color->rgb.b = n; | |
| 107 | break; | |
| 108 | } | |
| 109 | } | |
| 110 | } | |
| 111 | ||
| 112 | /* | |
| 113 | =back | |
| 114 | ||
| 115 | =head1 AUTHOR | |
| 116 | ||
| 117 | Tony Cook <tony@develop-help.com> | |
| 118 | ||
| 119 | =head1 SEE ALSO | |
| 120 | ||
| 121 | Imager | |
| 122 | ||
| 123 | =cut | |
| 124 | */ |