146 lines
4.6 KiB
Python
146 lines
4.6 KiB
Python
CopyRight = '''
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/**************************************************************************
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*
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* Copyright 2010 VMware, Inc.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
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* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/**
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* @file
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* SRGB translation.
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*
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* @author Brian Paul <brianp@vmware.com>
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* @author Michal Krol <michal@vmware.com>
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* @author Jose Fonseca <jfonseca@vmware.com>
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*/
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'''
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import math
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import struct
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def srgb_to_linear(x):
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if x <= 0.04045:
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return x / 12.92
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else:
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return math.pow((x + 0.055) / 1.055, 2.4)
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def linear_to_srgb(x):
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if x >= 0.0031308:
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return 1.055 * math.pow(x, 0.41666666) - 0.055
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else:
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return 12.92 * x
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def generate_srgb_tables():
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print('const float')
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print('util_format_srgb_8unorm_to_linear_float_table[256] = {')
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for j in range(0, 256, 4):
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print(' ', end=' ')
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print(' '.join(['%.7ef,' % srgb_to_linear(i / 255.0) for i in range(j, j + 4)]))
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print('};')
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print()
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print('const uint8_t')
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print('util_format_srgb_to_linear_8unorm_table[256] = {')
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for j in range(0, 256, 16):
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print(' ', end=' ')
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print(' '.join(['%3u,' % int(srgb_to_linear(i / 255.0) * 255.0 + 0.5) for i in range(j, j + 16)]))
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print('};')
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print()
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print('const uint8_t')
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print('util_format_linear_to_srgb_8unorm_table[256] = {')
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for j in range(0, 256, 16):
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print(' ', end=' ')
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print(' '.join(['%3u,' % int(linear_to_srgb(i / 255.0) * 255.0 + 0.5) for i in range(j, j + 16)]))
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print('};')
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print()
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# calculate the table interpolation values used in float linear to unorm8 srgb
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numexp = 13
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mantissa_msb = 3
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# stepshift is just used to only use every x-th float to make things faster,
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# 5 is largest value which still gives exact same table as 0
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stepshift = 5
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nbuckets = numexp << mantissa_msb
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bucketsize = (1 << (23 - mantissa_msb)) >> stepshift
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mantshift = 12
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valtable = []
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sum_aa = float(bucketsize)
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sum_ab = 0.0
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sum_bb = 0.0
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for i in range(0, bucketsize):
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j = (i << stepshift) >> mantshift
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sum_ab += j
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sum_bb += j*j
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inv_det = 1.0 / (sum_aa * sum_bb - sum_ab * sum_ab)
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for bucket in range(0, nbuckets):
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start = ((127 - numexp) << 23) + bucket*(bucketsize << stepshift)
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sum_a = 0.0
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sum_b = 0.0
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for i in range(0, bucketsize):
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j = (i << stepshift) >> mantshift
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fint = start + (i << stepshift)
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ffloat = struct.unpack('f', struct.pack('I', fint))[0]
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val = linear_to_srgb(ffloat) * 255.0 + 0.5
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sum_a += val
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sum_b += j*val
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solved_a = inv_det * (sum_bb*sum_a - sum_ab*sum_b)
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solved_b = inv_det * (sum_aa*sum_b - sum_ab*sum_a)
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scaled_a = solved_a * 65536.0 / 512.0
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scaled_b = solved_b * 65536.0
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int_a = int(scaled_a + 0.5)
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int_b = int(scaled_b + 0.5)
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valtable.append((int_a << 16) + int_b)
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print('const unsigned')
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print('util_format_linear_to_srgb_helper_table[104] = {')
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for j in range(0, nbuckets, 4):
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print(' ', end=' ')
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print(' '.join(['0x%08x,' % valtable[i] for i in range(j, j + 4)]))
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print('};')
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print()
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def main():
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print('/* This file is autogenerated by u_format_srgb.py. Do not edit directly. */')
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print()
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# This will print the copyright message on the top of this file
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print(CopyRight.strip())
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print()
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print('#include "format_srgb.h"')
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print()
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generate_srgb_tables()
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if __name__ == '__main__':
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main()
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