| 1 |
/* Copyright (c) 1998 Silicon Graphics, Inc. */ |
| 2 |
|
| 3 |
#ifndef lint |
| 4 |
static char SCCSid[] = "$SunId$ SGI"; |
| 5 |
#endif |
| 6 |
|
| 7 |
/* |
| 8 |
* Integer operations on COLR scanlines |
| 9 |
*/ |
| 10 |
|
| 11 |
#include "color.h" |
| 12 |
|
| 13 |
#define NULL 0 |
| 14 |
|
| 15 |
extern char *bmalloc(); |
| 16 |
|
| 17 |
#define MAXGSHIFT 31 /* maximum shift for gamma table */ |
| 18 |
|
| 19 |
static BYTE *g_mant = NULL, *g_nexp = NULL; |
| 20 |
|
| 21 |
static BYTE (*g_bval)[256] = NULL; |
| 22 |
|
| 23 |
#ifndef pow |
| 24 |
extern double pow(); |
| 25 |
#endif |
| 26 |
|
| 27 |
|
| 28 |
setcolrcor(f, a2) /* set brightness correction */ |
| 29 |
double (*f)(); |
| 30 |
double a2; |
| 31 |
{ |
| 32 |
double mult; |
| 33 |
register int i, j; |
| 34 |
/* allocate tables */ |
| 35 |
if (g_bval == NULL && (g_bval = |
| 36 |
(BYTE (*)[256])bmalloc((MAXGSHIFT+1)*256)) == NULL) |
| 37 |
return(-1); |
| 38 |
/* compute colr -> gamb mapping */ |
| 39 |
mult = 1.0/256.0; |
| 40 |
for (i = 0; i <= MAXGSHIFT; i++) { |
| 41 |
for (j = 0; j < 256; j++) |
| 42 |
g_bval[i][j] = 256.0 * (*f)((j+.5)*mult, a2); |
| 43 |
mult *= 0.5; |
| 44 |
} |
| 45 |
return(0); |
| 46 |
} |
| 47 |
|
| 48 |
|
| 49 |
setcolrinv(f, a2) /* set inverse brightness correction */ |
| 50 |
double (*f)(); |
| 51 |
double a2; |
| 52 |
{ |
| 53 |
double mult; |
| 54 |
register int i, j; |
| 55 |
/* allocate tables */ |
| 56 |
if (g_mant == NULL && (g_mant = (BYTE *)bmalloc(256)) == NULL) |
| 57 |
return(-1); |
| 58 |
if (g_nexp == NULL && (g_nexp = (BYTE *)bmalloc(256)) == NULL) |
| 59 |
return(-1); |
| 60 |
/* compute gamb -> colr mapping */ |
| 61 |
i = 0; |
| 62 |
mult = 256.0; |
| 63 |
for (j = 256; j--; ) { |
| 64 |
while ((g_mant[j] = mult * (*f)((j+.5)/256.0, a2)) < 128) { |
| 65 |
i++; |
| 66 |
mult *= 2.0; |
| 67 |
} |
| 68 |
g_nexp[j] = i; |
| 69 |
} |
| 70 |
return(0); |
| 71 |
} |
| 72 |
|
| 73 |
|
| 74 |
setcolrgam(g) /* set gamma conversion */ |
| 75 |
double g; |
| 76 |
{ |
| 77 |
if (setcolrcor(pow, 1.0/g) < 0) |
| 78 |
return(-1); |
| 79 |
return(setcolrinv(pow, g)); |
| 80 |
} |
| 81 |
|
| 82 |
|
| 83 |
colrs_gambs(scan, len) /* convert scanline of colrs to gamma bytes */ |
| 84 |
register COLR *scan; |
| 85 |
int len; |
| 86 |
{ |
| 87 |
register int i, expo; |
| 88 |
|
| 89 |
if (g_bval == NULL) |
| 90 |
return(-1); |
| 91 |
while (len-- > 0) { |
| 92 |
expo = scan[0][EXP] - COLXS; |
| 93 |
if (expo < -MAXGSHIFT) { |
| 94 |
if (expo < -MAXGSHIFT-8) { |
| 95 |
scan[0][RED] = |
| 96 |
scan[0][GRN] = |
| 97 |
scan[0][BLU] = 0; |
| 98 |
} else { |
| 99 |
i = (-MAXGSHIFT-1) - expo; |
| 100 |
scan[0][RED] = |
| 101 |
g_bval[MAXGSHIFT][((scan[0][RED]>>i)+1)>>1]; |
| 102 |
scan[0][GRN] = |
| 103 |
g_bval[MAXGSHIFT][((scan[0][GRN]>>i)+1)>>1]; |
| 104 |
scan[0][BLU] = |
| 105 |
g_bval[MAXGSHIFT][((scan[0][BLU]>>i)+1)>>1]; |
| 106 |
} |
| 107 |
} else if (expo > 0) { |
| 108 |
if (expo > 8) { |
| 109 |
scan[0][RED] = |
| 110 |
scan[0][GRN] = |
| 111 |
scan[0][BLU] = 255; |
| 112 |
} else { |
| 113 |
i = (scan[0][RED]<<1 | 1) << (expo-1); |
| 114 |
scan[0][RED] = i > 255 ? 255 : g_bval[0][i]; |
| 115 |
i = (scan[0][GRN]<<1 | 1) << (expo-1); |
| 116 |
scan[0][GRN] = i > 255 ? 255 : g_bval[0][i]; |
| 117 |
i = (scan[0][BLU]<<1 | 1) << (expo-1); |
| 118 |
scan[0][BLU] = i > 255 ? 255 : g_bval[0][i]; |
| 119 |
} |
| 120 |
} else { |
| 121 |
scan[0][RED] = g_bval[-expo][scan[0][RED]]; |
| 122 |
scan[0][GRN] = g_bval[-expo][scan[0][GRN]]; |
| 123 |
scan[0][BLU] = g_bval[-expo][scan[0][BLU]]; |
| 124 |
} |
| 125 |
scan[0][EXP] = COLXS; |
| 126 |
scan++; |
| 127 |
} |
| 128 |
return(0); |
| 129 |
} |
| 130 |
|
| 131 |
|
| 132 |
gambs_colrs(scan, len) /* convert gamma bytes to colr scanline */ |
| 133 |
register COLR *scan; |
| 134 |
int len; |
| 135 |
{ |
| 136 |
register int nexpo; |
| 137 |
|
| 138 |
if (g_mant == NULL | g_nexp == NULL) |
| 139 |
return(-1); |
| 140 |
while (len-- > 0) { |
| 141 |
nexpo = g_nexp[scan[0][RED]]; |
| 142 |
if (g_nexp[scan[0][GRN]] < nexpo) |
| 143 |
nexpo = g_nexp[scan[0][GRN]]; |
| 144 |
if (g_nexp[scan[0][BLU]] < nexpo) |
| 145 |
nexpo = g_nexp[scan[0][BLU]]; |
| 146 |
if (nexpo < g_nexp[scan[0][RED]]) |
| 147 |
scan[0][RED] = g_mant[scan[0][RED]] |
| 148 |
>> (g_nexp[scan[0][RED]]-nexpo); |
| 149 |
else |
| 150 |
scan[0][RED] = g_mant[scan[0][RED]]; |
| 151 |
if (nexpo < g_nexp[scan[0][GRN]]) |
| 152 |
scan[0][GRN] = g_mant[scan[0][GRN]] |
| 153 |
>> (g_nexp[scan[0][GRN]]-nexpo); |
| 154 |
else |
| 155 |
scan[0][GRN] = g_mant[scan[0][GRN]]; |
| 156 |
if (nexpo < g_nexp[scan[0][BLU]]) |
| 157 |
scan[0][BLU] = g_mant[scan[0][BLU]] |
| 158 |
>> (g_nexp[scan[0][BLU]]-nexpo); |
| 159 |
else |
| 160 |
scan[0][BLU] = g_mant[scan[0][BLU]]; |
| 161 |
scan[0][EXP] = COLXS - nexpo; |
| 162 |
scan++; |
| 163 |
} |
| 164 |
return(0); |
| 165 |
} |
| 166 |
|
| 167 |
|
| 168 |
shiftcolrs(scan, len, adjust) /* shift a scanline of colors by 2^adjust */ |
| 169 |
register COLR *scan; |
| 170 |
register int len; |
| 171 |
register int adjust; |
| 172 |
{ |
| 173 |
int minexp; |
| 174 |
|
| 175 |
if (adjust == 0) |
| 176 |
return; |
| 177 |
minexp = adjust < 0 ? -adjust : 0; |
| 178 |
while (len-- > 0) { |
| 179 |
if (scan[0][EXP] <= minexp) |
| 180 |
scan[0][RED] = scan[0][GRN] = scan[0][BLU] = |
| 181 |
scan[0][EXP] = 0; |
| 182 |
else |
| 183 |
scan[0][EXP] += adjust; |
| 184 |
scan++; |
| 185 |
} |
| 186 |
} |
| 187 |
|
| 188 |
|
| 189 |
normcolrs(scan, len, adjust) /* normalize a scanline of colrs */ |
| 190 |
register COLR *scan; |
| 191 |
int len; |
| 192 |
int adjust; |
| 193 |
{ |
| 194 |
register int c; |
| 195 |
register int shift; |
| 196 |
|
| 197 |
while (len-- > 0) { |
| 198 |
shift = scan[0][EXP] + adjust - COLXS; |
| 199 |
if (shift > 0) { |
| 200 |
if (shift > 8) { |
| 201 |
scan[0][RED] = |
| 202 |
scan[0][GRN] = |
| 203 |
scan[0][BLU] = 255; |
| 204 |
} else { |
| 205 |
shift--; |
| 206 |
c = (scan[0][RED]<<1 | 1) << shift; |
| 207 |
scan[0][RED] = c > 255 ? 255 : c; |
| 208 |
c = (scan[0][GRN]<<1 | 1) << shift; |
| 209 |
scan[0][GRN] = c > 255 ? 255 : c; |
| 210 |
c = (scan[0][BLU]<<1 | 1) << shift; |
| 211 |
scan[0][BLU] = c > 255 ? 255 : c; |
| 212 |
} |
| 213 |
} else if (shift < 0) { |
| 214 |
if (shift < -8) { |
| 215 |
scan[0][RED] = |
| 216 |
scan[0][GRN] = |
| 217 |
scan[0][BLU] = 0; |
| 218 |
} else { |
| 219 |
shift = -1-shift; |
| 220 |
scan[0][RED] = ((scan[0][RED]>>shift)+1)>>1; |
| 221 |
scan[0][GRN] = ((scan[0][GRN]>>shift)+1)>>1; |
| 222 |
scan[0][BLU] = ((scan[0][BLU]>>shift)+1)>>1; |
| 223 |
} |
| 224 |
} |
| 225 |
scan[0][EXP] = COLXS - adjust; |
| 226 |
scan++; |
| 227 |
} |
| 228 |
} |
