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
|
#!/usr/bin/env python3
import argparse
import math
import sys
# Note: we use a pure gamma 2.2 function, rather than the piece-wise
# sRGB transfer function, since that is what all compositors do.
def srgb_to_linear(f: float) -> float:
assert(f >= 0 and f <= 1.0)
return math.pow(f, 2.2)
def linear_to_srgb(f: float) -> float:
return math.pow(f, 1 / 2.2)
def main():
parser = argparse.ArgumentParser()
parser.add_argument('c_output', type=argparse.FileType('w'))
parser.add_argument('h_output', type=argparse.FileType('w'))
opts = parser.parse_args()
linear_table: list[int] = []
for i in range(256):
linear_table.append(int(srgb_to_linear(float(i) / 255) * 65535 + 0.5))
opts.h_output.write("#pragma once\n")
opts.h_output.write("#include <stdint.h>\n")
opts.h_output.write("\n")
opts.h_output.write('/* 8-bit input, 16-bit output */\n')
opts.h_output.write("extern const uint16_t srgb_decode_8_to_16_table[256];")
opts.h_output.write('\n')
opts.h_output.write('static inline uint16_t\n')
opts.h_output.write('srgb_decode_8_to_16(uint8_t v)\n')
opts.h_output.write('{\n')
opts.h_output.write(' return srgb_decode_8_to_16_table[v];\n')
opts.h_output.write('}\n')
opts.h_output.write('\n')
opts.h_output.write('/* 8-bit input, 8-bit output */\n')
opts.h_output.write("extern const uint8_t srgb_decode_8_to_8_table[256];\n")
opts.h_output.write('\n')
opts.h_output.write('static inline uint8_t\n')
opts.h_output.write('srgb_decode_8_to_8(uint8_t v)\n')
opts.h_output.write('{\n')
opts.h_output.write(' return srgb_decode_8_to_8_table[v];\n')
opts.h_output.write('}\n')
opts.c_output.write('#include "srgb.h"\n')
opts.c_output.write('\n')
opts.c_output.write("const uint16_t srgb_decode_8_to_16_table[256] = {\n")
for i in range(256):
opts.c_output.write(f' {linear_table[i]},\n')
opts.c_output.write('};\n')
opts.c_output.write("const uint8_t srgb_decode_8_to_8_table[256] = {\n")
for i in range(256):
opts.c_output.write(f' {linear_table[i] >> 8},\n')
opts.c_output.write('};\n')
if __name__ == '__main__':
sys.exit(main())
|
