blob: d5cbcf7646b7d83ebd24b73ab1ccc95604002db4 [file] [log] [blame]
 #!/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 * @author Michal Krol * @author Jose Fonseca */ ''' 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()