1 |
#ifndef lint |
2 |
static const char RCSid[] = "$Id: colrops.c,v 2.8 2003/03/10 17:13:29 greg Exp $"; |
3 |
#endif |
4 |
/* |
5 |
* Integer operations on COLR scanlines |
6 |
*/ |
7 |
|
8 |
#include "copyright.h" |
9 |
|
10 |
#include <stdio.h> |
11 |
#include <math.h> |
12 |
#include "color.h" |
13 |
|
14 |
extern char *bmalloc(); |
15 |
|
16 |
#define MAXGSHIFT 31 /* maximum shift for gamma table */ |
17 |
|
18 |
static BYTE *g_mant = NULL, *g_nexp = NULL; |
19 |
|
20 |
static BYTE (*g_bval)[256] = NULL; |
21 |
|
22 |
|
23 |
int |
24 |
setcolrcor(f, a2) /* set brightness correction */ |
25 |
double (*f)(); |
26 |
double a2; |
27 |
{ |
28 |
double mult; |
29 |
register int i, j; |
30 |
/* allocate tables */ |
31 |
if (g_bval == NULL && (g_bval = |
32 |
(BYTE (*)[256])bmalloc((MAXGSHIFT+1)*256)) == NULL) |
33 |
return(-1); |
34 |
/* compute colr -> gamb mapping */ |
35 |
mult = 1.0/256.0; |
36 |
for (i = 0; i <= MAXGSHIFT; i++) { |
37 |
for (j = 0; j < 256; j++) |
38 |
g_bval[i][j] = 256.0 * (*f)((j+.5)*mult, a2); |
39 |
mult *= 0.5; |
40 |
} |
41 |
return(0); |
42 |
} |
43 |
|
44 |
|
45 |
int |
46 |
setcolrinv(f, a2) /* set inverse brightness correction */ |
47 |
double (*f)(); |
48 |
double a2; |
49 |
{ |
50 |
double mult; |
51 |
register int i, j; |
52 |
/* allocate tables */ |
53 |
if (g_mant == NULL && (g_mant = (BYTE *)bmalloc(256)) == NULL) |
54 |
return(-1); |
55 |
if (g_nexp == NULL && (g_nexp = (BYTE *)bmalloc(256)) == NULL) |
56 |
return(-1); |
57 |
/* compute gamb -> colr mapping */ |
58 |
i = 0; |
59 |
mult = 256.0; |
60 |
for (j = 256; j--; ) { |
61 |
while ((g_mant[j] = mult * (*f)((j+.5)/256.0, a2)) < 128) { |
62 |
i++; |
63 |
mult *= 2.0; |
64 |
} |
65 |
g_nexp[j] = i; |
66 |
} |
67 |
return(0); |
68 |
} |
69 |
|
70 |
|
71 |
int |
72 |
setcolrgam(g) /* set gamma conversion */ |
73 |
double g; |
74 |
{ |
75 |
if (setcolrcor(pow, 1.0/g) < 0) |
76 |
return(-1); |
77 |
return(setcolrinv(pow, g)); |
78 |
} |
79 |
|
80 |
|
81 |
int |
82 |
colrs_gambs(scan, len) /* convert scanline of colrs to gamma bytes */ |
83 |
register COLR *scan; |
84 |
int len; |
85 |
{ |
86 |
register int i, expo; |
87 |
|
88 |
if (g_bval == NULL) |
89 |
return(-1); |
90 |
while (len-- > 0) { |
91 |
expo = scan[0][EXP] - COLXS; |
92 |
if (expo < -MAXGSHIFT) { |
93 |
if (expo < -MAXGSHIFT-8) { |
94 |
scan[0][RED] = |
95 |
scan[0][GRN] = |
96 |
scan[0][BLU] = 0; |
97 |
} else { |
98 |
i = (-MAXGSHIFT-1) - expo; |
99 |
scan[0][RED] = |
100 |
g_bval[MAXGSHIFT][((scan[0][RED]>>i)+1)>>1]; |
101 |
scan[0][GRN] = |
102 |
g_bval[MAXGSHIFT][((scan[0][GRN]>>i)+1)>>1]; |
103 |
scan[0][BLU] = |
104 |
g_bval[MAXGSHIFT][((scan[0][BLU]>>i)+1)>>1]; |
105 |
} |
106 |
} else if (expo > 0) { |
107 |
if (expo > 8) { |
108 |
scan[0][RED] = |
109 |
scan[0][GRN] = |
110 |
scan[0][BLU] = 255; |
111 |
} else { |
112 |
i = (scan[0][RED]<<1 | 1) << (expo-1); |
113 |
scan[0][RED] = i > 255 ? 255 : g_bval[0][i]; |
114 |
i = (scan[0][GRN]<<1 | 1) << (expo-1); |
115 |
scan[0][GRN] = i > 255 ? 255 : g_bval[0][i]; |
116 |
i = (scan[0][BLU]<<1 | 1) << (expo-1); |
117 |
scan[0][BLU] = i > 255 ? 255 : g_bval[0][i]; |
118 |
} |
119 |
} else { |
120 |
scan[0][RED] = g_bval[-expo][scan[0][RED]]; |
121 |
scan[0][GRN] = g_bval[-expo][scan[0][GRN]]; |
122 |
scan[0][BLU] = g_bval[-expo][scan[0][BLU]]; |
123 |
} |
124 |
scan[0][EXP] = COLXS; |
125 |
scan++; |
126 |
} |
127 |
return(0); |
128 |
} |
129 |
|
130 |
|
131 |
int |
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 |
void |
169 |
shiftcolrs(scan, len, adjust) /* shift a scanline of colors by 2^adjust */ |
170 |
register COLR *scan; |
171 |
register int len; |
172 |
register int adjust; |
173 |
{ |
174 |
int minexp; |
175 |
|
176 |
if (adjust == 0) |
177 |
return; |
178 |
minexp = adjust < 0 ? -adjust : 0; |
179 |
while (len-- > 0) { |
180 |
if (scan[0][EXP] <= minexp) |
181 |
scan[0][RED] = scan[0][GRN] = scan[0][BLU] = |
182 |
scan[0][EXP] = 0; |
183 |
else |
184 |
scan[0][EXP] += adjust; |
185 |
scan++; |
186 |
} |
187 |
} |
188 |
|
189 |
|
190 |
void |
191 |
normcolrs(scan, len, adjust) /* normalize a scanline of colrs */ |
192 |
register COLR *scan; |
193 |
int len; |
194 |
int adjust; |
195 |
{ |
196 |
register int c; |
197 |
register int shift; |
198 |
|
199 |
while (len-- > 0) { |
200 |
shift = scan[0][EXP] + adjust - COLXS; |
201 |
if (shift > 0) { |
202 |
if (shift > 8) { |
203 |
scan[0][RED] = |
204 |
scan[0][GRN] = |
205 |
scan[0][BLU] = 255; |
206 |
} else { |
207 |
shift--; |
208 |
c = (scan[0][RED]<<1 | 1) << shift; |
209 |
scan[0][RED] = c > 255 ? 255 : c; |
210 |
c = (scan[0][GRN]<<1 | 1) << shift; |
211 |
scan[0][GRN] = c > 255 ? 255 : c; |
212 |
c = (scan[0][BLU]<<1 | 1) << shift; |
213 |
scan[0][BLU] = c > 255 ? 255 : c; |
214 |
} |
215 |
} else if (shift < 0) { |
216 |
if (shift < -8) { |
217 |
scan[0][RED] = |
218 |
scan[0][GRN] = |
219 |
scan[0][BLU] = 0; |
220 |
} else { |
221 |
shift = -1-shift; |
222 |
scan[0][RED] = ((scan[0][RED]>>shift)+1)>>1; |
223 |
scan[0][GRN] = ((scan[0][GRN]>>shift)+1)>>1; |
224 |
scan[0][BLU] = ((scan[0][BLU]>>shift)+1)>>1; |
225 |
} |
226 |
} |
227 |
scan[0][EXP] = COLXS - adjust; |
228 |
scan++; |
229 |
} |
230 |
} |