source: trunk/src/oleaut32/libgif/quantize.c@ 22012

Last change on this file since 22012 was 10266, checked in by sandervl, 22 years ago

PF: GIF and JPEG static libs for IPicture interface implementation
File size: 12.3 KB
Line 
1/*****************************************************************************
2* "Gif-Lib" - Yet another gif library. *
3* *
4* Written by: Gershon Elber IBM PC Ver 0.1, Jun. 1989 *
5******************************************************************************
6* Module to quatize high resolution image into lower one. You may want to *
7* peek into the following article this code is based on: *
8* "Color Image Quantization for frame buffer Display", by Paul Heckbert *
9* SIGGRAPH 1982 page 297-307. *
10******************************************************************************
11* History: *
12* 5 Jan 90 - Version 1.0 by Gershon Elber. *
13*****************************************************************************/
14
15#ifdef __MSDOS__
16#include <dos.h>
17#include <alloc.h>
18#include <stdlib.h>
19#include <graphics.h>
20#endif /* __MSDOS__ */
21
22#ifndef __MSDOS__
23#include <stdlib.h>
24#endif
25#include <stdio.h>
26#include "gif_lib.h"
27
28#define PROGRAM_NAME "GIF_LIBRARY"
29
30#define ABS(x) ((x) > 0 ? (x) : (-(x)))
31
32/* The colors are stripped to 5 bits per primary color if non MSDOS system */
33/* or to 4 (not enough memory...) if MSDOS as first step. */
34#ifdef __MSDOS__
35#define COLOR_ARRAY_SIZE 4096
36#define BITS_PER_PRIM_COLOR 4
37#define MAX_PRIM_COLOR 0x0f
38#else
39#define COLOR_ARRAY_SIZE 32768
40#define BITS_PER_PRIM_COLOR 5
41#define MAX_PRIM_COLOR 0x1f
42#endif /* __MSDOS__ */
43
44extern int _GifError;
45
46#ifdef SYSV
47static char *VersionStr =
48 "Gif library module,\t\tEric S. Raymond\n\
49 (C) Copyright 1997 Eric S. Raymond\n";
50#else
51static char *VersionStr =
52 PROGRAM_NAME
53 " IBMPC "
54 GIF_LIB_VERSION
55 " Eric S. Raymond, "
56 __DATE__ ", " __TIME__ "\n"
57 "(C) Copyright 1997 Eric S. Raymond\n";
58#endif /* SYSV */
59
60static int SortRGBAxis;
61
62typedef struct QuantizedColorType {
63 GifByteType RGB[3];
64 GifByteType NewColorIndex;
65 long Count;
66 struct QuantizedColorType *Pnext;
67} QuantizedColorType;
68
69typedef struct NewColorMapType {
70 GifByteType RGBMin[3], RGBWidth[3];
71 unsigned int NumEntries;/* # of QuantizedColorType in linked list below. */
72 long Count; /* Total number of pixels in all the entries. */
73 QuantizedColorType *QuantizedColors;
74} NewColorMapType;
75
76static int SubdivColorMap(NewColorMapType *NewColorSubdiv,
77 unsigned int ColorMapSize,
78 unsigned int *NewColorMapSize);
79static int SortCmpRtn(const VoidPtr Entry1, const VoidPtr Entry2);
80
81/******************************************************************************
82* Quantize high resolution image into lower one. Input image consists of a *
83* 2D array for each of the RGB colors with size Width by Height. There is no *
84* Color map for the input. Output is a quantized image with 2D array of *
85* indexes into the output color map. *
86* Note input image can be 24 bits at the most (8 for red/green/blue) and *
87* the output has 256 colors at the most (256 entries in the color map.). *
88* ColorMapSize specifies size of color map up to 256 and will be updated to *
89* real size before returning. *
90* Also non of the parameter are allocated by this routine. *
91* This function returns GIF_OK if succesfull, GIF_ERROR otherwise. *
92******************************************************************************/
93int QuantizeBuffer(unsigned int Width, unsigned int Height, int *ColorMapSize,
94 GifByteType *RedInput, GifByteType *GreenInput, GifByteType *BlueInput,
95 GifByteType *OutputBuffer, GifColorType *OutputColorMap)
96{
97 unsigned int Index, NumOfEntries;
98 int i, j, MaxRGBError[3];
99 int NewColorMapSize;
100 long Red, Green, Blue;
101 NewColorMapType NewColorSubdiv[256];
102 QuantizedColorType *ColorArrayEntries, *QuantizedColor;
103
104 if ((ColorArrayEntries = (QuantizedColorType *)
105 malloc(sizeof(QuantizedColorType) * COLOR_ARRAY_SIZE)) == NULL) {
106 _GifError = E_GIF_ERR_NOT_ENOUGH_MEM;
107 return GIF_ERROR;
108 }
109
110 for (i = 0; i < COLOR_ARRAY_SIZE; i++) {
111 ColorArrayEntries[i].RGB[0]= i >> (2 * BITS_PER_PRIM_COLOR);
112 ColorArrayEntries[i].RGB[1] = (i >> BITS_PER_PRIM_COLOR) &
113 MAX_PRIM_COLOR;
114 ColorArrayEntries[i].RGB[2] = i & MAX_PRIM_COLOR;
115 ColorArrayEntries[i].Count = 0;
116 }
117
118 /* Sample the colors and their distribution: */
119 for (i = 0; i < (int)(Width * Height); i++) {
120 Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR))
121 << (2 * BITS_PER_PRIM_COLOR)) +
122 ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR))
123 << BITS_PER_PRIM_COLOR) +
124 (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
125 ColorArrayEntries[Index].Count++;
126 }
127
128 /* Put all the colors in the first entry of the color map, and call the */
129 /* recursive subdivision process. */
130 for (i = 0; i < 256; i++) {
131 NewColorSubdiv[i].QuantizedColors = NULL;
132 NewColorSubdiv[i].Count = NewColorSubdiv[i].NumEntries = 0;
133 for (j = 0; j < 3; j++) {
134 NewColorSubdiv[i].RGBMin[j] = 0;
135 NewColorSubdiv[i].RGBWidth[j] = 255;
136 }
137 }
138
139 /* Find the non empty entries in the color table and chain them: */
140 for (i = 0; i < COLOR_ARRAY_SIZE; i++)
141 if (ColorArrayEntries[i].Count > 0) break;
142 QuantizedColor = NewColorSubdiv[0].QuantizedColors = &ColorArrayEntries[i];
143 NumOfEntries = 1;
144 while (++i < COLOR_ARRAY_SIZE)
145 if (ColorArrayEntries[i].Count > 0) {
146 QuantizedColor -> Pnext = &ColorArrayEntries[i];
147 QuantizedColor = &ColorArrayEntries[i];
148 NumOfEntries++;
149 }
150 QuantizedColor -> Pnext = NULL;
151
152 NewColorSubdiv[0].NumEntries = NumOfEntries;/* Different sampled colors. */
153 NewColorSubdiv[0].Count = ((long) Width) * Height; /* Pixels. */
154 NewColorMapSize = 1;
155 if (SubdivColorMap(NewColorSubdiv, *ColorMapSize, &NewColorMapSize) !=
156 GIF_OK) {
157 free((char *) ColorArrayEntries);
158 return GIF_ERROR;
159 }
160 if (NewColorMapSize < *ColorMapSize) {
161 /* And clear rest of color map: */
162 for (i = NewColorMapSize; i < *ColorMapSize; i++)
163 OutputColorMap[i].Red =
164 OutputColorMap[i].Green =
165 OutputColorMap[i].Blue = 0;
166 }
167
168 /* Average the colors in each entry to be the color to be used in the */
169 /* output color map, and plug it into the output color map itself. */
170 for (i = 0; i < NewColorMapSize; i++) {
171 if ((j = NewColorSubdiv[i].NumEntries) > 0) {
172 QuantizedColor = NewColorSubdiv[i].QuantizedColors;
173 Red = Green = Blue = 0;
174 while (QuantizedColor) {
175 QuantizedColor -> NewColorIndex = i;
176 Red += QuantizedColor -> RGB[0];
177 Green += QuantizedColor -> RGB[1];
178 Blue += QuantizedColor -> RGB[2];
179 QuantizedColor = QuantizedColor -> Pnext;
180 }
181 OutputColorMap[i].Red = (Red << (8 - BITS_PER_PRIM_COLOR)) / j;
182 OutputColorMap[i].Green = (Green << (8 - BITS_PER_PRIM_COLOR)) / j;
183 OutputColorMap[i].Blue= (Blue << (8 - BITS_PER_PRIM_COLOR)) / j;
184 }
185 else
186 GIF_MESSAGE("Null entry in quantized color map - thats weird.");
187 }
188
189 /* Finally scan the input buffer again and put the mapped index in the */
190 /* output buffer. */
191 MaxRGBError[0] = MaxRGBError[1] = MaxRGBError[2] = 0;
192 for (i = 0; i < (int)(Width * Height); i++) {
193 Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR))
194 << (2 * BITS_PER_PRIM_COLOR)) +
195 ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR))
196 << BITS_PER_PRIM_COLOR) +
197 (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
198 Index = ColorArrayEntries[Index].NewColorIndex;
199 OutputBuffer[i] = Index;
200 if (MaxRGBError[0] < ABS(OutputColorMap[Index].Red - RedInput[i]))
201 MaxRGBError[0] = ABS(OutputColorMap[Index].Red - RedInput[i]);
202 if (MaxRGBError[1] < ABS(OutputColorMap[Index].Green - GreenInput[i]))
203 MaxRGBError[1] = ABS(OutputColorMap[Index].Green - GreenInput[i]);
204 if (MaxRGBError[2] < ABS(OutputColorMap[Index].Blue - BlueInput[i]))
205 MaxRGBError[2] = ABS(OutputColorMap[Index].Blue - BlueInput[i]);
206 }
207
208#ifdef DEBUG
209 fprintf(stderr,
210 "Quantization L(0) errors: Red = %d, Green = %d, Blue = %d.\n",
211 MaxRGBError[0], MaxRGBError[1], MaxRGBError[2]);
212#endif /* DEBUG */
213
214 free((char *) ColorArrayEntries);
215
216 *ColorMapSize = NewColorMapSize;
217
218 return GIF_OK;
219}
220
221/******************************************************************************
222* Routine to subdivide the RGB space recursively using median cut in each *
223* axes alternatingly until ColorMapSize different cubes exists. *
224* The biggest cube in one dimension is subdivide unless it has only one entry.*
225* Returns GIF_ERROR if failed, otherwise GIF_OK. *
226******************************************************************************/
227static int SubdivColorMap(NewColorMapType *NewColorSubdiv,
228 unsigned int ColorMapSize,
229 unsigned int *NewColorMapSize)
230{
231 int MaxSize;
232 unsigned int i, j, Index = 0, NumEntries, MinColor, MaxColor;
233 long Sum, Count;
234 QuantizedColorType *QuantizedColor, **SortArray;
235
236 while (ColorMapSize > *NewColorMapSize) {
237 /* Find candidate for subdivision: */
238 MaxSize = -1;
239 for (i = 0; i < *NewColorMapSize; i++) {
240 for (j = 0; j < 3; j++) {
241 if (((int) NewColorSubdiv[i].RGBWidth[j]) > MaxSize &&
242 NewColorSubdiv[i].NumEntries > 1) {
243 MaxSize = NewColorSubdiv[i].RGBWidth[j];
244 Index = i;
245 SortRGBAxis = j;
246 }
247 }
248 }
249
250 if (MaxSize == -1)
251 return GIF_OK;
252
253 /* Split the entry Index into two along the axis SortRGBAxis: */
254
255 /* Sort all elements in that entry along the given axis and split at */
256 /* the median. */
257 if ((SortArray = (QuantizedColorType **)
258 malloc(sizeof(QuantizedColorType *) *
259 NewColorSubdiv[Index].NumEntries)) == NULL)
260 return GIF_ERROR;
261 for (j = 0, QuantizedColor = NewColorSubdiv[Index].QuantizedColors;
262 j < NewColorSubdiv[Index].NumEntries && QuantizedColor != NULL;
263 j++, QuantizedColor = QuantizedColor -> Pnext)
264 SortArray[j] = QuantizedColor;
265 qsort(SortArray, NewColorSubdiv[Index].NumEntries,
266 sizeof(QuantizedColorType *), SortCmpRtn);
267
268 /* Relink the sorted list into one: */
269 for (j = 0; j < NewColorSubdiv[Index].NumEntries - 1; j++)
270 SortArray[j] -> Pnext = SortArray[j + 1];
271 SortArray[NewColorSubdiv[Index].NumEntries - 1] -> Pnext = NULL;
272 NewColorSubdiv[Index].QuantizedColors = QuantizedColor = SortArray[0];
273 free((char *) SortArray);
274
275 /* Now simply add the Counts until we have half of the Count: */
276 Sum = NewColorSubdiv[Index].Count / 2 - QuantizedColor -> Count;
277 NumEntries = 1;
278 Count = QuantizedColor -> Count;
279 while ((Sum -= QuantizedColor -> Pnext -> Count) >= 0 &&
280 QuantizedColor -> Pnext != NULL &&
281 QuantizedColor -> Pnext -> Pnext != NULL) {
282 QuantizedColor = QuantizedColor -> Pnext;
283 NumEntries++;
284 Count += QuantizedColor -> Count;
285 }
286 /* Save the values of the last color of the first half, and first */
287 /* of the second half so we can update the Bounding Boxes later. */
288 /* Also as the colors are quantized and the BBoxes are full 0..255, */
289 /* they need to be rescaled. */
290 MaxColor = QuantizedColor -> RGB[SortRGBAxis];/* Max. of first half. */
291 MinColor = QuantizedColor -> Pnext -> RGB[SortRGBAxis];/* of second. */
292 MaxColor <<= (8 - BITS_PER_PRIM_COLOR);
293 MinColor <<= (8 - BITS_PER_PRIM_COLOR);
294
295 /* Partition right here: */
296 NewColorSubdiv[*NewColorMapSize].QuantizedColors =
297 QuantizedColor -> Pnext;
298 QuantizedColor -> Pnext = NULL;
299 NewColorSubdiv[*NewColorMapSize].Count = Count;
300 NewColorSubdiv[Index].Count -= Count;
301 NewColorSubdiv[*NewColorMapSize].NumEntries =
302 NewColorSubdiv[Index].NumEntries - NumEntries;
303 NewColorSubdiv[Index].NumEntries = NumEntries;
304 for (j = 0; j < 3; j++) {
305 NewColorSubdiv[*NewColorMapSize].RGBMin[j] =
306 NewColorSubdiv[Index].RGBMin[j];
307 NewColorSubdiv[*NewColorMapSize].RGBWidth[j] =
308 NewColorSubdiv[Index].RGBWidth[j];
309 }
310 NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] =
311 NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] +
312 NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] -
313 MinColor;
314 NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] = MinColor;
315
316 NewColorSubdiv[Index].RGBWidth[SortRGBAxis] =
317 MaxColor - NewColorSubdiv[Index].RGBMin[SortRGBAxis];
318
319 (*NewColorMapSize)++;
320 }
321
322 return GIF_OK;
323}
324
325/******************************************************************************
326* Routine called by qsort to compare to entries. *
327******************************************************************************/
328static int SortCmpRtn(const VoidPtr Entry1, const VoidPtr Entry2)
329{
330 return (* ((QuantizedColorType **) Entry1)) -> RGB[SortRGBAxis] -
331 (* ((QuantizedColorType **) Entry2)) -> RGB[SortRGBAxis];
332}
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