| #!/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 <brianp@vmware.com> |
| * @author Michal Krol <michal@vmware.com> |
| * @author Jose Fonseca <jfonseca@vmware.com> |
| */ |
| ''' |
| |
| |
| 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() |