 Timestamp:
 May 27, 2009, 7:04:48 AM (11 years ago)
 File:

 1 edited
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libpipi/trunk/examples/img2twit.cpp
r3531 r3532 66 66 #define RANGE_H 4000 67 67 68 /* How does the algorithm work: one point per cell, or two */ 68 /* How does the algorithm work: one point per cell, or two? XXX: changing 69 * this value breaks compatibility with other images. */ 69 70 #define POINTS_PER_CELL 2 70 71 … … 128 129 /* Global triangulation */ 129 130 static Delaunay_triangulation dt; 131 132 /* 133 * Bit allocation handling 134 */ 135 136 void compute_ranges(int width, int height) 137 { 138 TOTAL_BITS = MAX_MSG_LEN * logf(NUM_CHARACTERS) / logf(2); 139 HEADER_BITS = logf(RANGE_W * RANGE_H) / logf(2); 140 DATA_BITS = TOTAL_BITS  HEADER_BITS; 141 #if POINTS_PER_CELL == 1 142 CELL_BITS = logf(RANGE_SYXRGB) / logf(2); 143 #else 144 // TODO: implement the following shit 145 //float coord_bits = logf((RANGE_Y * RANGE_X) * (RANGE_Y * RANGE_X + 1) / 2); 146 //float other_bits = logf(RANGE_R * RANGE_G * RANGE_B * RANGE_S); 147 //CELL_BITS = (coord_bits + 2 * other_bits) / logf(2); 148 CELL_BITS = 2 * logf(RANGE_SYXRGB) / logf(2); 149 #endif 150 TOTAL_CELLS = (int)(DATA_BITS / CELL_BITS); 151 MAX_ITERATIONS = ITERATIONS_PER_POINT * POINTS_PER_CELL * TOTAL_CELLS; 152 153 /* Compute "best" w/h ratio */ 154 dw = 1; dh = TOTAL_CELLS; 155 for(unsigned int i = 1; i <= TOTAL_CELLS; i++) 156 { 157 int j = TOTAL_CELLS / i; 158 159 float r = (float)width / (float)height; 160 float ir = (float)i / (float)j; 161 float dwr = (float)dw / (float)dh; 162 163 if(fabs(logf(r / ir)) < fabs(logf(r / dwr))) 164 { 165 dw = i; 166 dh = TOTAL_CELLS / dw; 167 } 168 } 169 while((dh + 1) * dw <= TOTAL_CELLS) dh++; 170 while(dh * (dw + 1) <= TOTAL_CELLS) dw++; 171 } 130 172 131 173 /* … … 445 487 static inline void index2cell(int index, int *dx, int *dy) 446 488 { 447 // This check will be used once we add points to our list 448 //if(index < dw * dh * POINTS_PER_CELL) 449 { 450 *dx = (index / POINTS_PER_CELL) % dw; 451 *dy = (index / POINTS_PER_CELL) / dw; 452 } 489 *dx = (index / POINTS_PER_CELL) % dw; 490 *dy = (index / POINTS_PER_CELL) / dw; 453 491 } 454 492 … … 1022 1060 } 1023 1061 1024 TOTAL_BITS = MAX_MSG_LEN * logf(NUM_CHARACTERS) / logf(2); 1025 HEADER_BITS = logf(RANGE_W * RANGE_H) / logf(2); 1026 DATA_BITS = TOTAL_BITS  HEADER_BITS; 1027 #if POINTS_PER_CELL == 1 1028 CELL_BITS = logf(RANGE_SYXRGB) / logf(2); 1029 #else 1030 // TODO: implement the following shit 1031 //float coord_bits = logf((RANGE_Y * RANGE_X) * (RANGE_Y * RANGE_X + 1) / 2); 1032 //float other_bits = logf(RANGE_R * RANGE_G * RANGE_B * RANGE_S); 1033 //CELL_BITS = (coord_bits + 2 * other_bits) / logf(2); 1034 CELL_BITS = 2 * logf(RANGE_SYXRGB) / logf(2); 1035 #endif 1036 TOTAL_CELLS = (int)(DATA_BITS / CELL_BITS); 1037 MAX_ITERATIONS = ITERATIONS_PER_POINT * POINTS_PER_CELL * TOTAL_CELLS; 1038 1039 /* Compute "best" w/h ratio */ 1040 dw = 1; dh = TOTAL_CELLS; 1041 for(unsigned int i = 1; i <= TOTAL_CELLS; i++) 1042 { 1043 int j = TOTAL_CELLS / i; 1044 1045 float r = (float)width / (float)height; 1046 float ir = (float)i / (float)j; 1047 float dwr = (float)dw / (float)dh; 1048 1049 if(fabs(logf(r / ir)) < fabs(logf(r / dwr))) 1050 { 1051 dw = i; 1052 dh = TOTAL_CELLS / dw; 1053 } 1054 } 1055 while((dh + 1) * dw <= TOTAL_CELLS) dh++; 1056 while(dh * (dw + 1) <= TOTAL_CELLS) dw++; 1062 compute_ranges(width, height); 1063 1064 /* Try to cram some more information into our points as long as it 1065 * does not change the cell distribution. This cannot be too clever, 1066 * because we want the computation to depend only on the source image 1067 * coordinates. */ 1068 #define TRY(op, revert) \ 1069 do { \ 1070 unsigned int olddw = dw, olddh = dh; \ 1071 op; compute_ranges(width, height); \ 1072 if(dw != olddw  dh != olddh) \ 1073 { revert; compute_ranges(width, height); } \ 1074 } while(0) 1075 1076 for(int i = 0; i < 5; i++) 1077 { 1078 TRY(RANGE_G++, RANGE_G); 1079 TRY(RANGE_R++, RANGE_R); 1080 TRY(RANGE_B++, RANGE_B); 1081 } 1082 1083 for(int i = 0; i < 10; i++) 1084 { 1085 if((float)width / dw >= (float)height / dh) 1086 { 1087 TRY(RANGE_X++, RANGE_X); 1088 TRY(RANGE_Y++, RANGE_Y); 1089 } 1090 else 1091 { 1092 TRY(RANGE_Y++, RANGE_Y); 1093 TRY(RANGE_X++, RANGE_X); 1094 } 1095 } 1057 1096 1058 1097 /* Print debug information */
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