Keith Platfoot | 9b8f860 | 2015-01-07 10:16:21 -0800 | [diff] [blame] | 1 | /***************************************************************************** |
| 2 | |
| 3 | quantize.c - quantize a high resolution image into lower one |
| 4 | |
| 5 | Based on: "Color Image Quantization for frame buffer Display", by |
| 6 | Paul Heckbert SIGGRAPH 1982 page 297-307. |
| 7 | |
| 8 | This doesn't really belong in the core library, was undocumented, |
| 9 | and was removed in 4.2. Then it turned out some client apps were |
| 10 | actually using it, so it was restored in 5.0. |
| 11 | |
| 12 | ******************************************************************************/ |
| 13 | |
| 14 | #include <stdlib.h> |
| 15 | #include <stdio.h> |
| 16 | #include "gif_lib.h" |
| 17 | #include "gif_lib_private.h" |
| 18 | |
| 19 | #define ABS(x) ((x) > 0 ? (x) : (-(x))) |
| 20 | |
| 21 | #define COLOR_ARRAY_SIZE 32768 |
| 22 | #define BITS_PER_PRIM_COLOR 5 |
| 23 | #define MAX_PRIM_COLOR 0x1f |
| 24 | |
| 25 | static int SortRGBAxis; |
| 26 | |
| 27 | typedef struct QuantizedColorType { |
| 28 | GifByteType RGB[3]; |
| 29 | GifByteType NewColorIndex; |
| 30 | long Count; |
| 31 | struct QuantizedColorType *Pnext; |
| 32 | } QuantizedColorType; |
| 33 | |
| 34 | typedef struct NewColorMapType { |
| 35 | GifByteType RGBMin[3], RGBWidth[3]; |
| 36 | unsigned int NumEntries; /* # of QuantizedColorType in linked list below */ |
| 37 | unsigned long Count; /* Total number of pixels in all the entries */ |
| 38 | QuantizedColorType *QuantizedColors; |
| 39 | } NewColorMapType; |
| 40 | |
| 41 | static int SubdivColorMap(NewColorMapType * NewColorSubdiv, |
| 42 | unsigned int ColorMapSize, |
| 43 | unsigned int *NewColorMapSize); |
| 44 | static int SortCmpRtn(const void *Entry1, const void *Entry2); |
| 45 | |
| 46 | /****************************************************************************** |
| 47 | Quantize high resolution image into lower one. Input image consists of a |
| 48 | 2D array for each of the RGB colors with size Width by Height. There is no |
| 49 | Color map for the input. Output is a quantized image with 2D array of |
| 50 | indexes into the output color map. |
| 51 | Note input image can be 24 bits at the most (8 for red/green/blue) and |
| 52 | the output has 256 colors at the most (256 entries in the color map.). |
| 53 | ColorMapSize specifies size of color map up to 256 and will be updated to |
| 54 | real size before returning. |
| 55 | Also non of the parameter are allocated by this routine. |
| 56 | This function returns GIF_OK if successful, GIF_ERROR otherwise. |
| 57 | ******************************************************************************/ |
| 58 | int |
| 59 | GifQuantizeBuffer(unsigned int Width, |
| 60 | unsigned int Height, |
| 61 | int *ColorMapSize, |
| 62 | GifByteType * RedInput, |
| 63 | GifByteType * GreenInput, |
| 64 | GifByteType * BlueInput, |
| 65 | GifByteType * OutputBuffer, |
| 66 | GifColorType * OutputColorMap) { |
| 67 | |
| 68 | unsigned int Index, NumOfEntries; |
| 69 | int i, j, MaxRGBError[3]; |
| 70 | unsigned int NewColorMapSize; |
| 71 | long Red, Green, Blue; |
| 72 | NewColorMapType NewColorSubdiv[256]; |
| 73 | QuantizedColorType *ColorArrayEntries, *QuantizedColor; |
| 74 | |
| 75 | ColorArrayEntries = (QuantizedColorType *)malloc( |
| 76 | sizeof(QuantizedColorType) * COLOR_ARRAY_SIZE); |
| 77 | if (ColorArrayEntries == NULL) { |
| 78 | return GIF_ERROR; |
| 79 | } |
| 80 | |
| 81 | for (i = 0; i < COLOR_ARRAY_SIZE; i++) { |
| 82 | ColorArrayEntries[i].RGB[0] = i >> (2 * BITS_PER_PRIM_COLOR); |
| 83 | ColorArrayEntries[i].RGB[1] = (i >> BITS_PER_PRIM_COLOR) & |
| 84 | MAX_PRIM_COLOR; |
| 85 | ColorArrayEntries[i].RGB[2] = i & MAX_PRIM_COLOR; |
| 86 | ColorArrayEntries[i].Count = 0; |
| 87 | } |
| 88 | |
| 89 | /* Sample the colors and their distribution: */ |
| 90 | for (i = 0; i < (int)(Width * Height); i++) { |
| 91 | Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << |
| 92 | (2 * BITS_PER_PRIM_COLOR)) + |
| 93 | ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << |
| 94 | BITS_PER_PRIM_COLOR) + |
| 95 | (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR)); |
| 96 | ColorArrayEntries[Index].Count++; |
| 97 | } |
| 98 | |
| 99 | /* Put all the colors in the first entry of the color map, and call the |
| 100 | * recursive subdivision process. */ |
| 101 | for (i = 0; i < 256; i++) { |
| 102 | NewColorSubdiv[i].QuantizedColors = NULL; |
| 103 | NewColorSubdiv[i].Count = NewColorSubdiv[i].NumEntries = 0; |
| 104 | for (j = 0; j < 3; j++) { |
| 105 | NewColorSubdiv[i].RGBMin[j] = 0; |
| 106 | NewColorSubdiv[i].RGBWidth[j] = 255; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /* Find the non empty entries in the color table and chain them: */ |
| 111 | for (i = 0; i < COLOR_ARRAY_SIZE; i++) |
| 112 | if (ColorArrayEntries[i].Count > 0) |
| 113 | break; |
| 114 | QuantizedColor = NewColorSubdiv[0].QuantizedColors = &ColorArrayEntries[i]; |
| 115 | NumOfEntries = 1; |
| 116 | while (++i < COLOR_ARRAY_SIZE) |
| 117 | if (ColorArrayEntries[i].Count > 0) { |
| 118 | QuantizedColor->Pnext = &ColorArrayEntries[i]; |
| 119 | QuantizedColor = &ColorArrayEntries[i]; |
| 120 | NumOfEntries++; |
| 121 | } |
| 122 | QuantizedColor->Pnext = NULL; |
| 123 | |
| 124 | NewColorSubdiv[0].NumEntries = NumOfEntries; /* Different sampled colors */ |
| 125 | NewColorSubdiv[0].Count = ((long)Width) * Height; /* Pixels */ |
| 126 | NewColorMapSize = 1; |
| 127 | if (SubdivColorMap(NewColorSubdiv, *ColorMapSize, &NewColorMapSize) != |
| 128 | GIF_OK) { |
| 129 | free((char *)ColorArrayEntries); |
| 130 | return GIF_ERROR; |
| 131 | } |
| 132 | if (NewColorMapSize < *ColorMapSize) { |
| 133 | /* And clear rest of color map: */ |
| 134 | for (i = NewColorMapSize; i < *ColorMapSize; i++) |
| 135 | OutputColorMap[i].Red = OutputColorMap[i].Green = |
| 136 | OutputColorMap[i].Blue = 0; |
| 137 | } |
| 138 | |
| 139 | /* Average the colors in each entry to be the color to be used in the |
| 140 | * output color map, and plug it into the output color map itself. */ |
| 141 | for (i = 0; i < NewColorMapSize; i++) { |
| 142 | if ((j = NewColorSubdiv[i].NumEntries) > 0) { |
| 143 | QuantizedColor = NewColorSubdiv[i].QuantizedColors; |
| 144 | Red = Green = Blue = 0; |
| 145 | while (QuantizedColor) { |
| 146 | QuantizedColor->NewColorIndex = i; |
| 147 | Red += QuantizedColor->RGB[0]; |
| 148 | Green += QuantizedColor->RGB[1]; |
| 149 | Blue += QuantizedColor->RGB[2]; |
| 150 | QuantizedColor = QuantizedColor->Pnext; |
| 151 | } |
| 152 | OutputColorMap[i].Red = (Red << (8 - BITS_PER_PRIM_COLOR)) / j; |
| 153 | OutputColorMap[i].Green = (Green << (8 - BITS_PER_PRIM_COLOR)) / j; |
| 154 | OutputColorMap[i].Blue = (Blue << (8 - BITS_PER_PRIM_COLOR)) / j; |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | /* Finally scan the input buffer again and put the mapped index in the |
| 159 | * output buffer. */ |
| 160 | MaxRGBError[0] = MaxRGBError[1] = MaxRGBError[2] = 0; |
| 161 | for (i = 0; i < (int)(Width * Height); i++) { |
| 162 | Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << |
| 163 | (2 * BITS_PER_PRIM_COLOR)) + |
| 164 | ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << |
| 165 | BITS_PER_PRIM_COLOR) + |
| 166 | (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR)); |
| 167 | Index = ColorArrayEntries[Index].NewColorIndex; |
| 168 | OutputBuffer[i] = Index; |
| 169 | if (MaxRGBError[0] < ABS(OutputColorMap[Index].Red - RedInput[i])) |
| 170 | MaxRGBError[0] = ABS(OutputColorMap[Index].Red - RedInput[i]); |
| 171 | if (MaxRGBError[1] < ABS(OutputColorMap[Index].Green - GreenInput[i])) |
| 172 | MaxRGBError[1] = ABS(OutputColorMap[Index].Green - GreenInput[i]); |
| 173 | if (MaxRGBError[2] < ABS(OutputColorMap[Index].Blue - BlueInput[i])) |
| 174 | MaxRGBError[2] = ABS(OutputColorMap[Index].Blue - BlueInput[i]); |
| 175 | } |
| 176 | |
| 177 | #ifdef DEBUG |
| 178 | fprintf(stderr, |
| 179 | "Quantization L(0) errors: Red = %d, Green = %d, Blue = %d.\n", |
| 180 | MaxRGBError[0], MaxRGBError[1], MaxRGBError[2]); |
| 181 | #endif /* DEBUG */ |
| 182 | |
| 183 | free((char *)ColorArrayEntries); |
| 184 | |
| 185 | *ColorMapSize = NewColorMapSize; |
| 186 | |
| 187 | return GIF_OK; |
| 188 | } |
| 189 | |
| 190 | /****************************************************************************** |
| 191 | Routine to subdivide the RGB space recursively using median cut in each |
| 192 | axes alternatingly until ColorMapSize different cubes exists. |
| 193 | The biggest cube in one dimension is subdivide unless it has only one entry. |
| 194 | Returns GIF_ERROR if failed, otherwise GIF_OK. |
| 195 | *******************************************************************************/ |
| 196 | static int |
| 197 | SubdivColorMap(NewColorMapType * NewColorSubdiv, |
| 198 | unsigned int ColorMapSize, |
| 199 | unsigned int *NewColorMapSize) { |
| 200 | |
| 201 | int MaxSize; |
| 202 | unsigned int i, j, Index = 0, NumEntries, MinColor, MaxColor; |
| 203 | long Sum, Count; |
| 204 | QuantizedColorType *QuantizedColor, **SortArray; |
| 205 | |
| 206 | while (ColorMapSize > *NewColorMapSize) { |
| 207 | /* Find candidate for subdivision: */ |
| 208 | MaxSize = -1; |
| 209 | for (i = 0; i < *NewColorMapSize; i++) { |
| 210 | for (j = 0; j < 3; j++) { |
| 211 | if ((((int)NewColorSubdiv[i].RGBWidth[j]) > MaxSize) && |
| 212 | (NewColorSubdiv[i].NumEntries > 1)) { |
| 213 | MaxSize = NewColorSubdiv[i].RGBWidth[j]; |
| 214 | Index = i; |
| 215 | SortRGBAxis = j; |
| 216 | } |
| 217 | } |
| 218 | } |
| 219 | |
| 220 | if (MaxSize == -1) |
| 221 | return GIF_OK; |
| 222 | |
| 223 | /* Split the entry Index into two along the axis SortRGBAxis: */ |
| 224 | |
| 225 | /* Sort all elements in that entry along the given axis and split at |
| 226 | * the median. */ |
| 227 | SortArray = (QuantizedColorType **)malloc( |
| 228 | sizeof(QuantizedColorType *) * |
| 229 | NewColorSubdiv[Index].NumEntries); |
| 230 | if (SortArray == NULL) |
| 231 | return GIF_ERROR; |
| 232 | for (j = 0, QuantizedColor = NewColorSubdiv[Index].QuantizedColors; |
| 233 | j < NewColorSubdiv[Index].NumEntries && QuantizedColor != NULL; |
| 234 | j++, QuantizedColor = QuantizedColor->Pnext) |
| 235 | SortArray[j] = QuantizedColor; |
| 236 | |
Leon Scroggins III | df596d3 | 2017-03-13 14:03:21 -0400 | [diff] [blame] | 237 | /* |
| 238 | * Because qsort isn't stable, this can produce differing |
| 239 | * results for the order of tuples depending on platform |
| 240 | * details of how qsort() is implemented. |
| 241 | * |
| 242 | * We mitigate this problem by sorting on all three axes rather |
| 243 | * than only the one specied by SortRGBAxis; that way the instability |
| 244 | * can only become an issue if there are multiple color indices |
| 245 | * referring to identical RGB tuples. Older versions of this |
| 246 | * sorted on only the one axis. |
| 247 | */ |
Keith Platfoot | 9b8f860 | 2015-01-07 10:16:21 -0800 | [diff] [blame] | 248 | qsort(SortArray, NewColorSubdiv[Index].NumEntries, |
| 249 | sizeof(QuantizedColorType *), SortCmpRtn); |
| 250 | |
| 251 | /* Relink the sorted list into one: */ |
| 252 | for (j = 0; j < NewColorSubdiv[Index].NumEntries - 1; j++) |
| 253 | SortArray[j]->Pnext = SortArray[j + 1]; |
| 254 | SortArray[NewColorSubdiv[Index].NumEntries - 1]->Pnext = NULL; |
| 255 | NewColorSubdiv[Index].QuantizedColors = QuantizedColor = SortArray[0]; |
| 256 | free((char *)SortArray); |
| 257 | |
| 258 | /* Now simply add the Counts until we have half of the Count: */ |
| 259 | Sum = NewColorSubdiv[Index].Count / 2 - QuantizedColor->Count; |
| 260 | NumEntries = 1; |
| 261 | Count = QuantizedColor->Count; |
| 262 | while (QuantizedColor->Pnext != NULL && |
| 263 | (Sum -= QuantizedColor->Pnext->Count) >= 0 && |
| 264 | QuantizedColor->Pnext->Pnext != NULL) { |
| 265 | QuantizedColor = QuantizedColor->Pnext; |
| 266 | NumEntries++; |
| 267 | Count += QuantizedColor->Count; |
| 268 | } |
| 269 | /* Save the values of the last color of the first half, and first |
| 270 | * of the second half so we can update the Bounding Boxes later. |
| 271 | * Also as the colors are quantized and the BBoxes are full 0..255, |
| 272 | * they need to be rescaled. |
| 273 | */ |
| 274 | MaxColor = QuantizedColor->RGB[SortRGBAxis]; /* Max. of first half */ |
| 275 | /* coverity[var_deref_op] */ |
| 276 | MinColor = QuantizedColor->Pnext->RGB[SortRGBAxis]; /* of second */ |
| 277 | MaxColor <<= (8 - BITS_PER_PRIM_COLOR); |
| 278 | MinColor <<= (8 - BITS_PER_PRIM_COLOR); |
| 279 | |
| 280 | /* Partition right here: */ |
| 281 | NewColorSubdiv[*NewColorMapSize].QuantizedColors = |
| 282 | QuantizedColor->Pnext; |
| 283 | QuantizedColor->Pnext = NULL; |
| 284 | NewColorSubdiv[*NewColorMapSize].Count = Count; |
| 285 | NewColorSubdiv[Index].Count -= Count; |
| 286 | NewColorSubdiv[*NewColorMapSize].NumEntries = |
| 287 | NewColorSubdiv[Index].NumEntries - NumEntries; |
| 288 | NewColorSubdiv[Index].NumEntries = NumEntries; |
| 289 | for (j = 0; j < 3; j++) { |
| 290 | NewColorSubdiv[*NewColorMapSize].RGBMin[j] = |
| 291 | NewColorSubdiv[Index].RGBMin[j]; |
| 292 | NewColorSubdiv[*NewColorMapSize].RGBWidth[j] = |
| 293 | NewColorSubdiv[Index].RGBWidth[j]; |
| 294 | } |
| 295 | NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] = |
| 296 | NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] + |
| 297 | NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] - MinColor; |
| 298 | NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] = MinColor; |
| 299 | |
| 300 | NewColorSubdiv[Index].RGBWidth[SortRGBAxis] = |
| 301 | MaxColor - NewColorSubdiv[Index].RGBMin[SortRGBAxis]; |
| 302 | |
| 303 | (*NewColorMapSize)++; |
| 304 | } |
| 305 | |
| 306 | return GIF_OK; |
| 307 | } |
| 308 | |
| 309 | /**************************************************************************** |
| 310 | Routine called by qsort to compare two entries. |
| 311 | *****************************************************************************/ |
Leon Scroggins III | df596d3 | 2017-03-13 14:03:21 -0400 | [diff] [blame] | 312 | |
Keith Platfoot | 9b8f860 | 2015-01-07 10:16:21 -0800 | [diff] [blame] | 313 | static int |
| 314 | SortCmpRtn(const void *Entry1, |
| 315 | const void *Entry2) { |
Leon Scroggins III | df596d3 | 2017-03-13 14:03:21 -0400 | [diff] [blame] | 316 | QuantizedColorType *entry1 = (*((QuantizedColorType **) Entry1)); |
| 317 | QuantizedColorType *entry2 = (*((QuantizedColorType **) Entry2)); |
Keith Platfoot | 9b8f860 | 2015-01-07 10:16:21 -0800 | [diff] [blame] | 318 | |
Leon Scroggins III | df596d3 | 2017-03-13 14:03:21 -0400 | [diff] [blame] | 319 | /* sort on all axes of the color space! */ |
| 320 | int hash1 = entry1->RGB[SortRGBAxis] * 256 * 256 |
| 321 | + entry1->RGB[(SortRGBAxis+1) % 3] * 256 |
| 322 | + entry1->RGB[(SortRGBAxis+2) % 3]; |
| 323 | int hash2 = entry2->RGB[SortRGBAxis] * 256 * 256 |
| 324 | + entry2->RGB[(SortRGBAxis+1) % 3] * 256 |
| 325 | + entry2->RGB[(SortRGBAxis+2) % 3]; |
| 326 | |
| 327 | return hash1 - hash2; |
Keith Platfoot | 9b8f860 | 2015-01-07 10:16:21 -0800 | [diff] [blame] | 328 | } |
| 329 | |
| 330 | /* end */ |