1CopyRight = ''' 2/************************************************************************** 3 * 4 * Copyright 2010 VMware, Inc. 5 * All Rights Reserved. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a 8 * copy of this software and associated documentation files (the 9 * "Software"), to deal in the Software without restriction, including 10 * without limitation the rights to use, copy, modify, merge, publish, 11 * distribute, sub license, and/or sell copies of the Software, and to 12 * permit persons to whom the Software is furnished to do so, subject to 13 * the following conditions: 14 * 15 * The above copyright notice and this permission notice (including the 16 * next paragraph) shall be included in all copies or substantial portions 17 * of the Software. 18 * 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 21 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. 22 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR 23 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 24 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 25 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 26 * 27 **************************************************************************/ 28 29/** 30 * @file 31 * SRGB translation. 32 * 33 * @author Brian Paul <brianp@vmware.com> 34 * @author Michal Krol <michal@vmware.com> 35 * @author Jose Fonseca <jfonseca@vmware.com> 36 */ 37''' 38 39 40import math 41import struct 42 43 44def srgb_to_linear(x): 45 if x <= 0.04045: 46 return x / 12.92 47 else: 48 return math.pow((x + 0.055) / 1.055, 2.4) 49 50 51def linear_to_srgb(x): 52 if x >= 0.0031308: 53 return 1.055 * math.pow(x, 0.41666666) - 0.055 54 else: 55 return 12.92 * x 56 57 58def generate_srgb_tables(): 59 print('const float') 60 print('util_format_srgb_8unorm_to_linear_float_table[256] = {') 61 for j in range(0, 256, 4): 62 print(' ', end=' ') 63 print(' '.join(['%.7ef,' % srgb_to_linear(i / 255.0) for i in range(j, j + 4)])) 64 print('};') 65 print() 66 print('const uint8_t') 67 print('util_format_srgb_to_linear_8unorm_table[256] = {') 68 for j in range(0, 256, 16): 69 print(' ', end=' ') 70 print(' '.join(['%3u,' % int(srgb_to_linear(i / 255.0) * 255.0 + 0.5) for i in range(j, j + 16)])) 71 print('};') 72 print() 73 print('const uint8_t') 74 print('util_format_linear_to_srgb_8unorm_table[256] = {') 75 for j in range(0, 256, 16): 76 print(' ', end=' ') 77 print(' '.join(['%3u,' % int(linear_to_srgb(i / 255.0) * 255.0 + 0.5) for i in range(j, j + 16)])) 78 print('};') 79 print() 80 81# calculate the table interpolation values used in float linear to unorm8 srgb 82 numexp = 13 83 mantissa_msb = 3 84# stepshift is just used to only use every x-th float to make things faster, 85# 5 is largest value which still gives exact same table as 0 86 stepshift = 5 87 nbuckets = numexp << mantissa_msb 88 bucketsize = (1 << (23 - mantissa_msb)) >> stepshift 89 mantshift = 12 90 valtable = [] 91 sum_aa = float(bucketsize) 92 sum_ab = 0.0 93 sum_bb = 0.0 94 for i in range(0, bucketsize): 95 j = (i << stepshift) >> mantshift 96 sum_ab += j 97 sum_bb += j*j 98 inv_det = 1.0 / (sum_aa * sum_bb - sum_ab * sum_ab) 99 100 for bucket in range(0, nbuckets): 101 start = ((127 - numexp) << 23) + bucket*(bucketsize << stepshift) 102 sum_a = 0.0 103 sum_b = 0.0 104 105 for i in range(0, bucketsize): 106 j = (i << stepshift) >> mantshift 107 fint = start + (i << stepshift) 108 ffloat = struct.unpack('f', struct.pack('I', fint))[0] 109 val = linear_to_srgb(ffloat) * 255.0 + 0.5 110 sum_a += val 111 sum_b += j*val 112 113 solved_a = inv_det * (sum_bb*sum_a - sum_ab*sum_b) 114 solved_b = inv_det * (sum_aa*sum_b - sum_ab*sum_a) 115 116 scaled_a = solved_a * 65536.0 / 512.0 117 scaled_b = solved_b * 65536.0 118 119 int_a = int(scaled_a + 0.5) 120 int_b = int(scaled_b + 0.5) 121 122 valtable.append((int_a << 16) + int_b) 123 124 print('const unsigned') 125 print('util_format_linear_to_srgb_helper_table[104] = {') 126 127 for j in range(0, nbuckets, 4): 128 print(' ', end=' ') 129 print(' '.join(['0x%08x,' % valtable[i] for i in range(j, j + 4)])) 130 print('};') 131 print() 132 133def main(): 134 print('/* This file is autogenerated by u_format_srgb.py. Do not edit directly. */') 135 print() 136 # This will print the copyright message on the top of this file 137 print(CopyRight.strip()) 138 print() 139 print('#include "format_srgb.h"') 140 print() 141 generate_srgb_tables() 142 143 144if __name__ == '__main__': 145 main() 146