1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
|
#include <stdio.h>
#include <stdint.h>
#include <math.h>
#include "lcms2_internal.h"
/**
* Premultiplied alpha. This conversion generates irreversible information loss.
*
* 8 bits:
* prgb = rgb * (alpha/255)
* rgb = prgb * (255 / alpha)
*
* 16 bits:
* prgb = rgb * (alpha/65535)
* rgb = prgb * (65535/alpha)
*
*/
uint8_t to_premul8_float(uint8_t rgb8, uint8_t a8)
{
double alpha_factor, rgb;
if (a8 == 0) return rgb8;
alpha_factor = (double) a8 / 255.0;
rgb = ((double) rgb8 * alpha_factor);
return (uint8_t)round(rgb);
}
uint8_t from_premul8_float(uint8_t rgb8, uint8_t a8)
{
double alpha_factor, rgb;
if (a8 == 0) return rgb8;
alpha_factor = 255.0 / (double)a8;
rgb = ((double)rgb8 * alpha_factor);
if (rgb > 255.0) rgb = 255.0;
return (uint8_t)round(rgb);
}
uint16_t to_premul16_float(uint16_t rgb16, uint16_t a16)
{
double alpha_factor, rgb;
if (a16 == 0) return rgb16;
alpha_factor = (double)a16 / 65535.0;
rgb = ((double)rgb16 * alpha_factor);
return (uint16_t)round(rgb);
}
uint16_t from_premul16_float(uint16_t rgb16, uint16_t a16)
{
double alpha_factor, rgb;
if (a16 == 0) return rgb16;
alpha_factor = 65535.0 / (double)a16;
rgb = ((double)rgb16 * alpha_factor);
if (rgb > 65535.0) rgb = 65535.0;
return (uint16_t)round(rgb);
}
/**
** Optimized versions
*
* alpha_factor goes 0..1.0 in 1.15 fixed point format
* (a16 / 0xffff) which equals to _cmsToFixedDomain() inline (15.16)
*
* rgb 16.0 fixed point x alpha factor 1.15 = (a*b + 0x8000) >> 15
*
*/
uint16_t to_premul16(uint16_t rgb16, uint16_t a16)
{
uint32_t alpha_factor, rgb;
if (a16 == 0) return rgb16;
alpha_factor = _cmsToFixedDomain(a16);
rgb = ((uint32_t) rgb16 * alpha_factor + 0x8000) >> 16;
return (uint16_t)rgb;
}
uint16_t from_premul16(uint16_t rgb16, uint16_t a16)
{
uint32_t alpha_factor, rgb;
if (a16 == 0) return rgb16;
alpha_factor = _cmsToFixedDomain(a16);
rgb = (((uint32_t) rgb16) << 16) / alpha_factor;
if (rgb > 0xffff) rgb = 0xffff;
return (uint16_t)rgb;
}
uint8_t to_premul8(uint8_t rgb8, uint8_t a8)
{
uint32_t alpha_factor, rgb;
if (a8 == 0) return rgb8;
alpha_factor = _cmsToFixedDomain(FROM_8_TO_16(a8));
rgb = ((uint32_t)rgb8 * alpha_factor + 0x8000) >> 16;
return (uint8_t)rgb;
}
uint8_t from_premul8(uint8_t rgb8, uint8_t a8)
{
uint32_t alpha_factor, rgb;
if (a8 == 0) return rgb8;
alpha_factor = _cmsToFixedDomain(FROM_8_TO_16(a8));
rgb = (((uint32_t)rgb8) << 16) / alpha_factor;
if (rgb > 0xff) rgb = 0xff;
return (uint8_t)rgb;
}
static
void dif16to(void)
{
int32_t gpremul, gpremul1;
int32_t max, max1, max2, a, g;
printf("Premul TO diff\n");
max = max1 = max2 = 0;
for (a = 0; a < 65536; a += 255)
for (g = 0; g < 65536; g++)
{
gpremul = to_premul16_float(g, a);
gpremul1 = to_premul16(g, a);
if (gpremul != gpremul1)
{
int32_t dif = abs(gpremul - gpremul1);
if (dif > max)
{
max = dif;
max1 = gpremul;
max2 = gpremul1;
}
}
}
printf("Error max=%d on pre:%d pre1:%d\n", max, max1, max2);
}
static
void dif16from(void)
{
int32_t gpremul, gpremul1;
int32_t max, max1, max2, maxa, maxg, a, g;
printf("Premul FROM diff\n");
max = max1 = max2 = maxa = maxg = 0;
for (a = 0; a < 65536; a += 255)
for (g = 0; g < 65536; g++)
{
gpremul = from_premul16_float(g, a);
gpremul1 = from_premul16(g, a);
if (gpremul != gpremul1)
{
int32_t dif = abs(gpremul - gpremul1);
if (dif > max)
{
max = dif;
max1 = gpremul;
max2 = gpremul1;
maxa = a;
maxg = g;
}
}
}
printf("Error max=%d on pre:%d pre1:%d (a:%d g:%d)\n", max, max1, max2, maxa, maxg);
from_premul16_float(maxg, maxa);
from_premul16(maxg, maxa);
}
static
void dif8to(void)
{
int32_t gpremul, gpremul1;
int32_t max, max1, max2, a, g;
printf("Premul TO8 diff\n");
max = max1 = max2 = 0;
for (a = 0; a < 256; a++)
for (g = 0; g < 256; g++)
{
gpremul = to_premul8_float(g, a);
gpremul1 = to_premul8(g, a);
if (gpremul != gpremul1)
{
int32_t dif = abs(gpremul - gpremul1);
if (dif > max)
{
max = dif;
max1 = gpremul;
max2 = gpremul1;
}
}
}
printf("Error max=%d on pre:%d pre1:%d\n", max, max1, max2);
}
static
void dif8from(void)
{
int32_t gpremul, gpremul1;
int32_t max, max1, max2, maxa, maxg, a, g;
printf("Premul FROM8 diff\n");
max = max1 = max2 = maxa = maxg = 0;
for (a = 0; a < 256; a++)
for (g = 0; g < 256; g++)
{
gpremul = from_premul8_float(g, a);
gpremul1 = from_premul8(g, a);
if (gpremul != gpremul1)
{
int32_t dif = abs(gpremul - gpremul1);
if (dif > max)
{
max = dif;
max1 = gpremul;
max2 = gpremul1;
maxa = a;
maxg = g;
}
}
}
printf("Error max=%d on pre:%d pre1:%d (a:%d g:%d)\n", max, max1, max2, maxa, maxg);
from_premul8_float(maxg, maxa);
from_premul8(maxg, maxa);
}
static
void toFixedDomain(void)
{
int32_t g;
for (g = 0; g < 65536; g++)
{
uint32_t a = _cmsToFixedDomain(g);
uint32_t b = (uint32_t)round(((double)g / 65535.0) * 65536.0);
if (a != b)
printf("%d != %d\n", a, b);
}
}
static
void fromFixedDomain(void)
{
int32_t g;
for (g = 0; g <= 65536; g++)
{
uint32_t a = _cmsFromFixedDomain(g);
uint32_t b = (uint32_t)round(((double)g / 65536.0) * 65535.0);
if (a != b)
printf("%d != %d\n", a, b);
}
}
// Check alpha
int main()
{
toFixedDomain();
fromFixedDomain();
dif8from();
dif8to();
dif16from();
dif16to();
return 0;
}
|
