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| 1 | /* |
| 2 | * ccube.c - Color mapper based on color cube model |
| 3 | * |
| 4 | * Written 2011 by Werner Almesberger |
| 5 | * Copyright 2011 Werner Almesberger |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | */ |
| 12 | |
| 13 | |
| 14 | #include <stdint.h> |
| 15 | |
| 16 | #include "ubb-vga.h" |
| 17 | |
| 18 | |
| 19 | #define W_RGB (256*0.5) |
| 20 | #define W_Y (256*0.25) |
| 21 | #define W_0 (256*0.125) |
| 22 | |
| 23 | |
| 24 | static struct col { |
| 25 | uint8_t r, g, b; |
| 26 | } col[16]; |
| 27 | |
| 28 | |
| 29 | uint8_t ccube_map(uint8_t r, uint8_t g, uint8_t b) |
| 30 | { |
| 31 | unsigned best = 0; |
| 32 | int best_i = 0; |
| 33 | unsigned d; |
| 34 | int i; |
| 35 | |
| 36 | for (i = 0; i != 16; i++) { |
| 37 | d = (r-col[i].r)*(r-col[i].r)+ |
| 38 | (g-col[i].g)*(g-col[i].g)+ |
| 39 | (b-col[i].b)*(b-col[i].b); |
| 40 | if (!i || d < best) { |
| 41 | best = d; |
| 42 | best_i = i; |
| 43 | } |
| 44 | } |
| 45 | return best_i; |
| 46 | } |
| 47 | |
| 48 | |
| 49 | void ccube_init(void) |
| 50 | { |
| 51 | int i; |
| 52 | |
| 53 | for (i = 0; i != 16; i++) { |
| 54 | col[i].r = W_0+(i & R_VAL ? W_RGB : 0)+(i & Y_VAL ? W_Y : 0); |
| 55 | col[i].g = W_0+(i & G_VAL ? W_RGB : 0)+(i & Y_VAL ? W_Y : 0); |
| 56 | col[i].b = W_0+(i & B_VAL ? W_RGB : 0)+(i & Y_VAL ? W_Y : 0); |
| 57 | } |
| 58 | } |
| 59 |
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