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greg |
2.1 |
#ifndef lint |
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greg |
2.18 |
static const char RCSid[] = "$Id: clrtab.c,v 2.17 2004/03/28 20:33:13 schorsch Exp $"; |
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greg |
2.1 |
#endif |
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/* |
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* Simple median-cut color quantization based on colortab.c |
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*/ |
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schorsch |
2.15 |
#include "copyright.h" |
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#include <string.h> |
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greg |
2.1 |
#include "standard.h" |
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schorsch |
2.15 |
#include "color.h" |
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schorsch |
2.17 |
#include "clrtab.h" |
15 |
greg |
2.1 |
|
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/* histogram resolution */ |
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#define NRED 36 |
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#define NGRN 48 |
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#define NBLU 24 |
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#define HMAX NGRN |
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/* minimum box count for adaptive partition */ |
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#define MINSAMP 7 |
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/* color partition */ |
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#define set_branch(p,c) ((c)<<2|(p)) |
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#define part(cn) ((cn)>>2) |
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#define prim(cn) ((cn)&3) |
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/* our color table (global) */ |
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greg |
2.10 |
extern BYTE clrtab[256][3]; |
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greg |
2.1 |
/* histogram of colors / color assignments */ |
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static unsigned histo[NRED][NGRN][NBLU]; |
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#define cndx(c) histo[((c)[RED]*NRED)>>8][((c)[GRN]*NGRN)>>8][((c)[BLU]*NBLU)>>8] |
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/* initial color cube boundary */ |
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schorsch |
2.17 |
static int CLRCUBE[3][2] = {{0,NRED},{0,NGRN},{0,NBLU}}; |
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greg |
2.1 |
/* maximum propagated error during dithering */ |
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#define MAXERR 20 |
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greg |
2.2 |
/* define CLOSEST to get closest colors */ |
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greg |
2.4 |
#ifndef CLOSEST |
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#define CLOSEST 1 /* this step takes a little longer */ |
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#endif |
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greg |
2.1 |
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schorsch |
2.17 |
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42 |
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#ifdef CLOSEST |
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static void closest(int n); |
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static void setclosest(BYTE *nl[], int r, int g, int b); |
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static void addneigh(BYTE *nl[], int i, int j); |
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static unsigned int dist(BYTE col[3], int r, int g, int b); |
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#endif |
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static void cut(int box[3][2], int c0, int c1); |
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static int split(int box[3][2]); |
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static void mktabent(int p, int box[3][2]); |
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greg |
2.11 |
|
52 |
greg |
2.1 |
|
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schorsch |
2.17 |
extern int |
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new_histo( /* clear our histogram */ |
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int n |
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) |
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greg |
2.1 |
{ |
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schorsch |
2.15 |
memset((void *)histo, '\0', sizeof(histo)); |
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greg |
2.10 |
return(0); |
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greg |
2.1 |
} |
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schorsch |
2.17 |
extern void |
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cnt_pixel( /* add pixel to our histogram */ |
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register BYTE col[] |
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) |
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greg |
2.1 |
{ |
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cndx(col)++; |
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} |
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schorsch |
2.17 |
extern void |
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cnt_colrs( /* add a scanline to our histogram */ |
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register COLR *cs, |
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register int n |
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) |
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greg |
2.1 |
{ |
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while (n-- > 0) { |
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cndx(cs[0])++; |
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cs++; |
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} |
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} |
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schorsch |
2.17 |
extern int |
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new_clrtab( /* make new color table using ncolors */ |
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int ncolors |
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) |
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greg |
2.1 |
{ |
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if (ncolors < 1) |
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return(0); |
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if (ncolors > 256) |
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ncolors = 256; |
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/* partition color space */ |
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cut(CLRCUBE, 0, ncolors); |
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greg |
2.2 |
#ifdef CLOSEST |
97 |
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closest(ncolors); /* ensure colors picked are closest */ |
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#endif |
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greg |
2.9 |
/* reset dithering function */ |
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dith_colrs((BYTE *)NULL, (COLR *)NULL, 0); |
101 |
greg |
2.1 |
/* return new color table size */ |
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return(ncolors); |
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} |
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schorsch |
2.17 |
extern int |
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map_pixel( /* get pixel for color */ |
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register BYTE col[] |
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) |
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greg |
2.1 |
{ |
111 |
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return(cndx(col)); |
112 |
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} |
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114 |
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schorsch |
2.17 |
extern void |
116 |
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map_colrs( /* convert a scanline to color index values */ |
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register BYTE *bs, |
118 |
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register COLR *cs, |
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register int n |
120 |
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) |
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greg |
2.1 |
{ |
122 |
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while (n-- > 0) { |
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*bs++ = cndx(cs[0]); |
124 |
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cs++; |
125 |
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} |
126 |
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} |
127 |
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128 |
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129 |
schorsch |
2.17 |
extern void |
130 |
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dith_colrs( /* convert scanline to dithered index values */ |
131 |
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register BYTE *bs, |
132 |
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register COLR *cs, |
133 |
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int n |
134 |
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) |
135 |
greg |
2.1 |
{ |
136 |
greg |
2.8 |
static short (*cerr)[3] = NULL; |
137 |
greg |
2.1 |
static int N = 0; |
138 |
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int err[3], errp[3]; |
139 |
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register int x, i; |
140 |
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141 |
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if (n != N) { /* get error propogation array */ |
142 |
greg |
2.8 |
if (N) { |
143 |
greg |
2.12 |
free((void *)cerr); |
144 |
greg |
2.8 |
cerr = NULL; |
145 |
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} |
146 |
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if (n) |
147 |
greg |
2.1 |
cerr = (short (*)[3])malloc(3*n*sizeof(short)); |
148 |
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if (cerr == NULL) { |
149 |
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N = 0; |
150 |
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map_colrs(bs, cs, n); |
151 |
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return; |
152 |
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} |
153 |
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N = n; |
154 |
schorsch |
2.15 |
memset((void *)cerr, '\0', 3*N*sizeof(short)); |
155 |
greg |
2.1 |
} |
156 |
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err[0] = err[1] = err[2] = 0; |
157 |
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for (x = 0; x < n; x++) { |
158 |
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for (i = 0; i < 3; i++) { /* dither value */ |
159 |
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errp[i] = err[i]; |
160 |
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err[i] += cerr[x][i]; |
161 |
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#ifdef MAXERR |
162 |
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if (err[i] > MAXERR) err[i] = MAXERR; |
163 |
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else if (err[i] < -MAXERR) err[i] = -MAXERR; |
164 |
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#endif |
165 |
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err[i] += cs[x][i]; |
166 |
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if (err[i] < 0) err[i] = 0; |
167 |
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else if (err[i] > 255) err[i] = 255; |
168 |
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} |
169 |
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bs[x] = cndx(err); |
170 |
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for (i = 0; i < 3; i++) { /* propagate error */ |
171 |
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err[i] -= clrtab[bs[x]][i]; |
172 |
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err[i] /= 3; |
173 |
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cerr[x][i] = err[i] + errp[i]; |
174 |
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} |
175 |
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} |
176 |
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} |
177 |
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178 |
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179 |
schorsch |
2.17 |
static void |
180 |
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cut( /* partition color space */ |
181 |
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register int box[3][2], |
182 |
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int c0, |
183 |
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int c1 |
184 |
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) |
185 |
greg |
2.1 |
{ |
186 |
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register int branch; |
187 |
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int kb[3][2]; |
188 |
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189 |
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if (c1-c0 <= 1) { /* assign pixel */ |
190 |
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mktabent(c0, box); |
191 |
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return; |
192 |
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} |
193 |
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/* split box */ |
194 |
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branch = split(box); |
195 |
schorsch |
2.15 |
memcpy((void *)kb, (void *)box, sizeof(kb)); |
196 |
greg |
2.1 |
/* do left (lesser) branch */ |
197 |
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kb[prim(branch)][1] = part(branch); |
198 |
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cut(kb, c0, (c0+c1)>>1); |
199 |
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/* do right branch */ |
200 |
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kb[prim(branch)][0] = part(branch); |
201 |
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kb[prim(branch)][1] = box[prim(branch)][1]; |
202 |
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cut(kb, (c0+c1)>>1, c1); |
203 |
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} |
204 |
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205 |
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206 |
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static int |
207 |
schorsch |
2.17 |
split( /* find median cut for box */ |
208 |
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register int box[3][2] |
209 |
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) |
210 |
greg |
2.1 |
{ |
211 |
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#define c0 r |
212 |
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register int r, g, b; |
213 |
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int pri; |
214 |
greg |
2.6 |
long t[HMAX], med; |
215 |
greg |
2.1 |
/* find dominant axis */ |
216 |
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pri = RED; |
217 |
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if (box[GRN][1]-box[GRN][0] > box[pri][1]-box[pri][0]) |
218 |
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pri = GRN; |
219 |
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if (box[BLU][1]-box[BLU][0] > box[pri][1]-box[pri][0]) |
220 |
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pri = BLU; |
221 |
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/* sum histogram over box */ |
222 |
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med = 0; |
223 |
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switch (pri) { |
224 |
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case RED: |
225 |
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for (r = box[RED][0]; r < box[RED][1]; r++) { |
226 |
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t[r] = 0; |
227 |
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for (g = box[GRN][0]; g < box[GRN][1]; g++) |
228 |
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for (b = box[BLU][0]; b < box[BLU][1]; b++) |
229 |
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t[r] += histo[r][g][b]; |
230 |
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med += t[r]; |
231 |
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} |
232 |
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break; |
233 |
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case GRN: |
234 |
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for (g = box[GRN][0]; g < box[GRN][1]; g++) { |
235 |
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t[g] = 0; |
236 |
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for (b = box[BLU][0]; b < box[BLU][1]; b++) |
237 |
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for (r = box[RED][0]; r < box[RED][1]; r++) |
238 |
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t[g] += histo[r][g][b]; |
239 |
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med += t[g]; |
240 |
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} |
241 |
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break; |
242 |
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case BLU: |
243 |
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for (b = box[BLU][0]; b < box[BLU][1]; b++) { |
244 |
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t[b] = 0; |
245 |
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for (r = box[RED][0]; r < box[RED][1]; r++) |
246 |
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for (g = box[GRN][0]; g < box[GRN][1]; g++) |
247 |
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t[b] += histo[r][g][b]; |
248 |
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med += t[b]; |
249 |
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} |
250 |
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break; |
251 |
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} |
252 |
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if (med < MINSAMP) /* if too sparse, split at midpoint */ |
253 |
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return(set_branch(pri,(box[pri][0]+box[pri][1])>>1)); |
254 |
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/* find median position */ |
255 |
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med >>= 1; |
256 |
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for (c0 = box[pri][0]; med > 0; c0++) |
257 |
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med -= t[c0]; |
258 |
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if (c0 > (box[pri][0]+box[pri][1])>>1) /* if past the midpoint */ |
259 |
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c0--; /* part left of median */ |
260 |
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return(set_branch(pri,c0)); |
261 |
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#undef c0 |
262 |
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} |
263 |
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264 |
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265 |
schorsch |
2.17 |
static void |
266 |
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mktabent( /* compute average color for box and assign */ |
267 |
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int p, |
268 |
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register int box[3][2] |
269 |
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) |
270 |
greg |
2.1 |
{ |
271 |
greg |
2.5 |
unsigned long sum[3]; |
272 |
greg |
2.7 |
unsigned r, g; |
273 |
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unsigned long n; |
274 |
greg |
2.5 |
register unsigned b, c; |
275 |
greg |
2.1 |
/* sum pixels in box */ |
276 |
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n = 0; |
277 |
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sum[RED] = sum[GRN] = sum[BLU] = 0; |
278 |
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for (r = box[RED][0]; r < box[RED][1]; r++) |
279 |
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for (g = box[GRN][0]; g < box[GRN][1]; g++) |
280 |
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for (b = box[BLU][0]; b < box[BLU][1]; b++) { |
281 |
schorsch |
2.16 |
if ( (c = histo[r][g][b]) ) { |
282 |
greg |
2.1 |
n += c; |
283 |
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sum[RED] += (long)c*r; |
284 |
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sum[GRN] += (long)c*g; |
285 |
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sum[BLU] += (long)c*b; |
286 |
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} |
287 |
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histo[r][g][b] = p; /* assign pixel */ |
288 |
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} |
289 |
greg |
2.7 |
if (n >= (1L<<23)/HMAX) { /* avoid overflow */ |
290 |
greg |
2.5 |
sum[RED] /= n; |
291 |
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sum[GRN] /= n; |
292 |
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sum[BLU] /= n; |
293 |
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n = 1; |
294 |
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} |
295 |
greg |
2.1 |
if (n) { /* compute average */ |
296 |
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clrtab[p][RED] = sum[RED]*256/NRED/n; |
297 |
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clrtab[p][GRN] = sum[GRN]*256/NGRN/n; |
298 |
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clrtab[p][BLU] = sum[BLU]*256/NBLU/n; |
299 |
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} else { /* empty box -- use midpoint */ |
300 |
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clrtab[p][RED] = (box[RED][0]+box[RED][1])*256/NRED/2; |
301 |
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clrtab[p][GRN] = (box[GRN][0]+box[GRN][1])*256/NGRN/2; |
302 |
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clrtab[p][BLU] = (box[BLU][0]+box[BLU][1])*256/NBLU/2; |
303 |
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} |
304 |
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} |
305 |
greg |
2.2 |
|
306 |
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307 |
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#ifdef CLOSEST |
308 |
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#define NBSIZ 32 |
309 |
schorsch |
2.17 |
static void |
310 |
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closest( /* make sure we have the closest colors */ |
311 |
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int n |
312 |
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) |
313 |
greg |
2.2 |
{ |
314 |
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BYTE *neigh[256]; |
315 |
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register int r, g, b; |
316 |
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#define i r |
317 |
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/* get space for neighbor lists */ |
318 |
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for (i = 0; i < n; i++) { |
319 |
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if ((neigh[i] = (BYTE *)malloc(NBSIZ)) == NULL) { |
320 |
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while (i--) |
321 |
|
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free(neigh[i]); |
322 |
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return; /* ENOMEM -- abandon effort */ |
323 |
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} |
324 |
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neigh[i][0] = i; /* identity is terminator */ |
325 |
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} |
326 |
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/* make neighbor lists */ |
327 |
greg |
2.3 |
for (r = 0; r < NRED; r++) |
328 |
|
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for (g = 0; g < NGRN; g++) |
329 |
|
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for (b = 0; b < NBLU; b++) { |
330 |
|
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if (r < NRED-1 && histo[r][g][b] != histo[r+1][g][b]) |
331 |
greg |
2.2 |
addneigh(neigh, histo[r][g][b], histo[r+1][g][b]); |
332 |
greg |
2.3 |
if (g < NGRN-1 && histo[r][g][b] != histo[r][g+1][b]) |
333 |
greg |
2.2 |
addneigh(neigh, histo[r][g][b], histo[r][g+1][b]); |
334 |
greg |
2.3 |
if (b < NBLU-1 && histo[r][g][b] != histo[r][g][b+1]) |
335 |
greg |
2.2 |
addneigh(neigh, histo[r][g][b], histo[r][g][b+1]); |
336 |
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} |
337 |
|
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/* assign closest values */ |
338 |
|
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for (r = 0; r < NRED; r++) |
339 |
|
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for (g = 0; g < NGRN; g++) |
340 |
|
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for (b = 0; b < NBLU; b++) |
341 |
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setclosest(neigh, r, g, b); |
342 |
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/* free neighbor lists */ |
343 |
|
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for (i = 0; i < n; i++) |
344 |
|
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free(neigh[i]); |
345 |
|
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#undef i |
346 |
|
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} |
347 |
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348 |
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|
349 |
schorsch |
2.17 |
static void |
350 |
|
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addneigh( /* i and j are neighbors; add them to list */ |
351 |
|
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register BYTE *nl[], |
352 |
|
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register int i, |
353 |
|
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int j |
354 |
|
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) |
355 |
greg |
2.2 |
{ |
356 |
|
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int nc; |
357 |
|
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char *nnl; |
358 |
|
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register int t; |
359 |
|
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|
360 |
|
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for (nc = 0; nc < 2; nc++) { /* do both neighbors */ |
361 |
|
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for (t = 0; nl[i][t] != i; t++) |
362 |
|
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if (nl[i][t] == j) |
363 |
|
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break; /* in list already */ |
364 |
|
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if (nl[i][t] == i) { /* add to list */ |
365 |
|
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nl[i][t++] = j; |
366 |
|
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if (t % NBSIZ == 0) { /* enlarge list */ |
367 |
greg |
2.13 |
if ((nnl = realloc((void *)nl[i], |
368 |
|
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t+NBSIZ)) == NULL) |
369 |
greg |
2.2 |
t--; |
370 |
|
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else |
371 |
|
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nl[i] = (BYTE *)nnl; |
372 |
|
|
} |
373 |
|
|
nl[i][t] = i; /* terminator */ |
374 |
|
|
} |
375 |
|
|
t = i; i = j; j = t; /* swap and do it again */ |
376 |
|
|
} |
377 |
|
|
} |
378 |
|
|
|
379 |
|
|
|
380 |
schorsch |
2.17 |
static unsigned int |
381 |
|
|
dist( /* find distance from clrtab entry to r,g,b */ |
382 |
|
|
register BYTE col[3], |
383 |
|
|
int r, |
384 |
|
|
int g, |
385 |
|
|
int b |
386 |
|
|
) |
387 |
greg |
2.2 |
{ |
388 |
greg |
2.4 |
register int tmp; |
389 |
greg |
2.2 |
register unsigned sum; |
390 |
|
|
|
391 |
|
|
tmp = col[RED]*NRED/256 - r; |
392 |
|
|
sum = tmp*tmp; |
393 |
|
|
tmp = col[GRN]*NGRN/256 - g; |
394 |
|
|
sum += tmp*tmp; |
395 |
|
|
tmp = col[BLU]*NBLU/256 - b; |
396 |
|
|
sum += tmp*tmp; |
397 |
|
|
return(sum); |
398 |
|
|
} |
399 |
|
|
|
400 |
|
|
|
401 |
schorsch |
2.17 |
static void |
402 |
|
|
setclosest( /* find index closest to color and assign */ |
403 |
|
|
BYTE *nl[], |
404 |
|
|
int r, |
405 |
|
|
int g, |
406 |
|
|
int b |
407 |
|
|
) |
408 |
greg |
2.2 |
{ |
409 |
|
|
int ident; |
410 |
|
|
unsigned min; |
411 |
|
|
register unsigned d; |
412 |
|
|
register BYTE *p; |
413 |
|
|
/* get starting value */ |
414 |
|
|
min = dist(clrtab[ident=histo[r][g][b]], r, g, b); |
415 |
|
|
/* find minimum */ |
416 |
|
|
for (p = nl[ident]; *p != ident; p++) |
417 |
|
|
if ((d = dist(clrtab[*p], r, g, b)) < min) { |
418 |
|
|
min = d; |
419 |
|
|
histo[r][g][b] = *p; |
420 |
|
|
} |
421 |
|
|
} |
422 |
|
|
#endif |