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floyd_steinberg_dither.c

  1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
  2 the authors of referenced articles or incorporated external code:
  3 http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?action=history&offset=20080916082812
  4 
  5 Permission is hereby granted, free of charge, to any person obtaining
  6 a copy of this software and associated documentation files (the
  7 "Software"), to deal in the Software without restriction, including
  8 without limitation the rights to use, copy, modify, merge, publish,
  9 distribute, sublicense, and/or sell copies of the Software, and to
 10 permit persons to whom the Software is furnished to do so, subject to
 11 the following conditions:
 12 
 13 The above copyright notice and this permission notice shall be
 14 included in all copies or substantial portions of the Software.
 15 
 16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 23 
 24 Retrieved from: http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?oldid=14630
 25 */
 26 
 27 #include <stdlib.h>

 28 
 29 #include "floyd_steinberg_dither.h"

 30 
 31 #define plus_truncate_uchar(a, b) \

 32     if (((int)(a)) + (b) < 0) \
 33         (a) = 0; \
 34     else if (((int)(a)) + (b) > 255) \
 35         (a) = 255; \
 36     else \
 37         (a) += (b);
 38 
 39 
 40 static
 41 unsigned char FindNearestColor(RGBTriple color, RGBPalette palette) {
 42     int i, distanceSquared, minDistanceSquared, bestIndex = 0;
 43     minDistanceSquared = 255*255 + 255*255 + 255*255 + 1;
 44     for (i=0; i<palette.size; i++) {
 45         int Rdiff = ((int)color.R) - palette.table[i].R;
 46         int Gdiff = ((int)color.G) - palette.table[i].G;
 47         int Bdiff = ((int)color.B) - palette.table[i].B;
 48         distanceSquared = Rdiff*Rdiff + Gdiff*Gdiff + Bdiff*Bdiff;
 49         if (distanceSquared < minDistanceSquared) {
 50             minDistanceSquared = distanceSquared;
 51             bestIndex = i;
 52         }
 53     }
 54     return bestIndex;
 55 }
 56 
 57 
 58 #define compute_disperse(channel) \

 59 error = ((int)(currentPixel->channel)) - palette.table[index].channel; \
 60 if (x + 1 < image.width) { \
 61     plus_truncate_uchar(image.pixels[(x+1) + (y+0)*image.width].channel, (error*7) >> 4); \
 62 } \
 63 if (y + 1 < image.height) { \
 64     if (x - 1 > 0) { \
 65         plus_truncate_uchar(image.pixels[(x-1) + (y+1)*image.width].channel, (error*3) >> 4); \
 66     } \
 67     plus_truncate_uchar(image.pixels[(x+0) + (y+1)*image.width].channel, (error*5) >> 4); \
 68     if (x + 1 < image.width) { \
 69         plus_truncate_uchar(image.pixels[(x+1) + (y+1)*image.width].channel, (error*1) >> 4); \
 70     } \
 71 }
 72 
 73 
 74 PalettizedImage FloydSteinbergDither(RGBImage image, RGBPalette palette)
 75 
 76 {
 77     PalettizedImage result;
 78     result.width = image.width;
 79     result.height = image.height;
 80     result.pixels = malloc(sizeof(unsigned char) * result.width * result.height);
 81 
 82 
 83     {
 84     int x, y;
 85     for(y = 0; y < image.height; y++) {
 86         for(x = 0; x < image.width; x++) {
 87         RGBTriple* currentPixel = &(image.pixels[x + y*image.width]);
 88         unsigned char index = FindNearestColor(*currentPixel, palette);
 89 	result.pixels[x + y*result.width] = index;
 90 
 91         {
 92 	    int error;
 93 	    compute_disperse(R);
 94 	    compute_disperse(G);
 95 	    compute_disperse(B);
 96 	}
 97 
 98         }
 99     }
100     }
101 
102     return result;
103 }
104 
105 
106


floyd_steinberg_dither.h

 1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
 2 the authors of referenced articles or incorporated external code:
 3 http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?action=history&offset=20080916082812
 4 
 5 Permission is hereby granted, free of charge, to any person obtaining
 6 a copy of this software and associated documentation files (the
 7 "Software"), to deal in the Software without restriction, including
 8 without limitation the rights to use, copy, modify, merge, publish,
 9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12 
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15 
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 
24 Retrieved from: http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?oldid=14630
25 */
26 
27 #ifndef _FLOYD_STEINBERG_DITHER_H_

28 
29 typedef struct {
30     unsigned char R, G, B;
31 } RGBTriple;
32 
33 typedef struct {
34     int size;
35     RGBTriple* table;
36 } RGBPalette;
37 
38 typedef struct {
39     int width, height;
40     RGBTriple* pixels;
41 } RGBImage;
42 
43 typedef struct {
44     int width, height;
45     unsigned char* pixels;
46 } PalettizedImage;
47 
48 PalettizedImage FloydSteinbergDither(RGBImage image, RGBPalette palette)
49 ;
50 
51 #endif /* #ifndef _FLOYD_STEINBERG_DITHER_H_ */

52


floyd_steinberg_dither_sample.c

  1 /* Copyright (c) 2010 the authors listed at the following URL, and/or
  2 the authors of referenced articles or incorporated external code:
  3 http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?action=history&offset=20080916082812
  4 
  5 Permission is hereby granted, free of charge, to any person obtaining
  6 a copy of this software and associated documentation files (the
  7 "Software"), to deal in the Software without restriction, including
  8 without limitation the rights to use, copy, modify, merge, publish,
  9 distribute, sublicense, and/or sell copies of the Software, and to
 10 permit persons to whom the Software is furnished to do so, subject to
 11 the following conditions:
 12 
 13 The above copyright notice and this permission notice shall be
 14 included in all copies or substantial portions of the Software.
 15 
 16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 23 
 24 Retrieved from: http://en.literateprograms.org/Floyd-Steinberg_dithering_(C)?oldid=14630
 25 */
 26 
 27 #include <stdio.h>

 28 #include <stdlib.h>

 29 #include "floyd_steinberg_dither.h"

 30 
 31 int main(int argc, char* argv[]) {
 32     int x, y;
 33     RGBImage image;
 34     RGBPalette palette;
 35     PalettizedImage result;
 36     FILE * raw_in, * raw_out;
 37 
 38     image.width = 100;
 39     image.height = 145;
 40     image.pixels = malloc(sizeof(RGBTriple) *
 41                    image.width * image.height);
 42 
 43     raw_in = fopen(argv[1], "rb");
 44     for(y = 0; y < image.height; y++) {
 45         for(x = 0; x < image.width; x++) {
 46             fread(&image.pixels[x + y*image.width],
 47                   3, 1, raw_in);
 48         }
 49     }
 50     fclose(raw_in);
 51 
 52     palette.size = 16;
 53     palette.table = malloc(sizeof(RGBTriple) * 16);
 54     palette.table[0].R = 149;
 55     palette.table[0].G = 91;
 56     palette.table[0].B = 110;
 57     palette.table[1].R = 176;
 58     palette.table[1].G = 116;
 59     palette.table[1].B = 137;
 60     palette.table[2].R = 17;
 61     palette.table[2].G = 11;
 62     palette.table[2].B = 15;
 63     palette.table[3].R = 63;
 64     palette.table[3].G = 47;
 65     palette.table[3].B = 69;
 66     palette.table[4].R = 93;
 67     palette.table[4].G = 75;
 68     palette.table[4].B = 112;
 69     palette.table[5].R = 47;
 70     palette.table[5].G = 62;
 71     palette.table[5].B = 24;
 72     palette.table[6].R = 76;
 73     palette.table[6].G = 90;
 74     palette.table[6].B = 55;
 75     palette.table[7].R = 190;
 76     palette.table[7].G = 212;
 77     palette.table[7].B = 115;
 78     palette.table[8].R = 160;
 79     palette.table[8].G = 176;
 80     palette.table[8].B = 87;
 81     palette.table[9].R = 116;
 82     palette.table[9].G = 120;
 83     palette.table[9].B = 87;
 84     palette.table[10].R = 245;
 85     palette.table[10].G = 246;
 86     palette.table[10].B = 225;
 87     palette.table[11].R = 148;
 88     palette.table[11].G = 146;
 89     palette.table[11].B = 130;
 90     palette.table[12].R = 200;
 91     palette.table[12].G = 195;
 92     palette.table[12].B = 180;
 93     palette.table[13].R = 36;
 94     palette.table[13].G = 32;
 95     palette.table[13].B = 27;
 96     palette.table[14].R = 87;
 97     palette.table[14].G = 54;
 98     palette.table[14].B = 45;
 99     palette.table[15].R = 121;
100     palette.table[15].G = 72;
101     palette.table[15].B = 72;
102 
103     result = FloydSteinbergDither(image, palette);
104 
105     raw_out = fopen(argv[2], "wb");
106     for(y = 0; y < result.height; y++) {
107         for(x = 0; x < result.width; x++) {
108             fwrite(&palette.table[result.pixels[x + y*image.width]],
109                    3, 1, raw_out);
110         }
111     }
112     fclose(raw_out);
113 
114     return 0;
115 }
116


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