mirror of
https://codeberg.org/dnkl/foot.git
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91 lines
2.5 KiB
Python
91 lines
2.5 KiB
Python
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#!/usr/bin/env python3
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import argparse
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import math
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import sys
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def srgb_to_linear(f: float) -> float:
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assert(f >= 0 and f <= 1.0)
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if f <= 0.04045:
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return f / 12.92
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return math.pow((f + 0.055) / 1.055, 2.4)
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def linear_to_srgb(f: float) -> float:
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if f < 0.0031308:
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return f * 12.92
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return 1.055 * math.pow(f, 1 / 2.4) - 0.055
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def main():
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parser = argparse.ArgumentParser()
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parser.add_argument('c_output', type=argparse.FileType('w'))
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parser.add_argument('h_output', type=argparse.FileType('w'))
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opts = parser.parse_args()
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linear_table: list[int] = []
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srgb_table: list[int] = []
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for i in range(256):
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linear_table.append(int(srgb_to_linear(float(i) / 255) * 65535 + 0.5))
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for i in range(4096):
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srgb_table.append(int(linear_to_srgb(float(i) / 4095) * 255 + 0.5))
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for i in range(256):
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while True:
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linear = linear_table[i]
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srgb = srgb_table[linear >> 4]
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if i == srgb:
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break
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linear_table[i] += 1
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opts.h_output.write("#pragma once\n")
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opts.h_output.write("#include <stdint.h>\n")
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opts.h_output.write("\n")
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opts.h_output.write('/* 8-bit input, 16-bit output */\n')
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opts.h_output.write("extern const uint16_t srgb_decode_8_to_16_table[256];")
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opts.h_output.write('\n')
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opts.h_output.write('static inline uint16_t\n')
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opts.h_output.write('srgb_decode_8_to_16(uint8_t v)\n')
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opts.h_output.write('{\n')
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opts.h_output.write(' return srgb_decode_8_to_16_table[v];\n')
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opts.h_output.write('}\n')
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opts.h_output.write('\n')
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opts.h_output.write('/* 8-bit input, 8-bit output */\n')
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opts.h_output.write("extern const uint8_t srgb_decode_8_to_8_table[256];\n")
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opts.h_output.write('\n')
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opts.h_output.write('static inline uint8_t\n')
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opts.h_output.write('srgb_decode_8_to_8(uint8_t v)\n')
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opts.h_output.write('{\n')
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opts.h_output.write(' return srgb_decode_8_to_8_table[v];\n')
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opts.h_output.write('}\n')
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opts.c_output.write('#include "srgb.h"\n')
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opts.c_output.write('\n')
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opts.c_output.write("const uint16_t srgb_decode_8_to_16_table[256] = {\n")
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for i in range(256):
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opts.c_output.write(f' {linear_table[i]},\n')
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opts.c_output.write('};\n')
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opts.c_output.write("const uint8_t srgb_decode_8_to_8_table[256] = {\n")
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for i in range(256):
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opts.c_output.write(f' {linear_table[i] >> 8},\n')
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opts.c_output.write('};\n')
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if __name__ == '__main__':
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sys.exit(main())
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