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Diffstat (limited to 'src/util/format_srgb.py')
| -rw-r--r-- | src/util/format_srgb.py | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/src/util/format_srgb.py b/src/util/format_srgb.py new file mode 100644 index 00000000000..d5cbcf7646b --- /dev/null +++ b/src/util/format_srgb.py @@ -0,0 +1,155 @@ +#!/usr/bin/env python + +CopyRight = ''' +/************************************************************************** + * + * Copyright 2010 VMware, Inc. + * All Rights Reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the + * "Software"), to deal in the Software without restriction, including + * without limitation the rights to use, copy, modify, merge, publish, + * distribute, sub license, and/or sell copies of the Software, and to + * permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice (including the + * next paragraph) shall be included in all copies or substantial portions + * of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. + * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR + * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, + * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE + * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + * + **************************************************************************/ + +/** + * @file + * SRGB translation. + * + * @author Brian Paul <[email protected]> + * @author Michal Krol <[email protected]> + * @author Jose Fonseca <[email protected]> + */ +''' + + +import math +import struct + + +def srgb_to_linear(x): + if x <= 0.04045: + return x / 12.92 + else: + return math.pow((x + 0.055) / 1.055, 2.4) + + +def linear_to_srgb(x): + if x >= 0.0031308: + return 1.055 * math.pow(x, 0.41666666) - 0.055 + else: + return 12.92 * x + + +def generate_srgb_tables(): + print 'const float' + print 'util_format_srgb_8unorm_to_linear_float_table[256] = {' + for j in range(0, 256, 4): + print ' ', + for i in range(j, j + 4): + print '%.7e,' % (srgb_to_linear(i / 255.0),), + print + print '};' + print + print 'const uint8_t' + print 'util_format_srgb_to_linear_8unorm_table[256] = {' + for j in range(0, 256, 16): + print ' ', + for i in range(j, j + 16): + print '%3u,' % (int(srgb_to_linear(i / 255.0) * 255.0 + 0.5),), + print + print '};' + print + print 'const uint8_t' + print 'util_format_linear_to_srgb_8unorm_table[256] = {' + for j in range(0, 256, 16): + print ' ', + for i in range(j, j + 16): + print '%3u,' % (int(linear_to_srgb(i / 255.0) * 255.0 + 0.5),), + print + print '};' + print + +# calculate the table interpolation values used in float linear to unorm8 srgb + numexp = 13 + mantissa_msb = 3 +# stepshift is just used to only use every x-th float to make things faster, +# 5 is largest value which still gives exact same table as 0 + stepshift = 5 + nbuckets = numexp << mantissa_msb + bucketsize = (1 << (23 - mantissa_msb)) >> stepshift + mantshift = 12 + valtable = [] + sum_aa = float(bucketsize) + sum_ab = 0.0 + sum_bb = 0.0 + for i in range(0, bucketsize): + j = (i << stepshift) >> mantshift + sum_ab += j + sum_bb += j*j + inv_det = 1.0 / (sum_aa * sum_bb - sum_ab * sum_ab) + + for bucket in range(0, nbuckets): + start = ((127 - numexp) << 23) + bucket*(bucketsize << stepshift) + sum_a = 0.0 + sum_b = 0.0 + + for i in range(0, bucketsize): + j = (i << stepshift) >> mantshift + fint = start + (i << stepshift) + ffloat = struct.unpack('f', struct.pack('I', fint))[0] + val = linear_to_srgb(ffloat) * 255.0 + 0.5 + sum_a += val + sum_b += j*val + + solved_a = inv_det * (sum_bb*sum_a - sum_ab*sum_b) + solved_b = inv_det * (sum_aa*sum_b - sum_ab*sum_a) + + scaled_a = solved_a * 65536.0 / 512.0 + scaled_b = solved_b * 65536.0 + + int_a = int(scaled_a + 0.5) + int_b = int(scaled_b + 0.5) + + valtable.append((int_a << 16) + int_b) + + print 'const unsigned' + print 'util_format_linear_to_srgb_helper_table[104] = {' + + for j in range(0, nbuckets, 4): + print ' ', + for i in range(j, j + 4): + print '0x%08x,' % (valtable[i],), + print + print '};' + print + +def main(): + print '/* This file is autogenerated by u_format_srgb.py. Do not edit directly. */' + print + # This will print the copyright message on the top of this file + print CopyRight.strip() + print + print '#include "format_srgb.h"' + print + generate_srgb_tables() + + +if __name__ == '__main__': + main() |