1 /**************************************************************************
2 *
3 * Copyright 2010 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
18 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
19 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
20 * USE OR OTHER DEALINGS IN THE SOFTWARE.
21 *
22 * The above copyright notice and this permission notice (including the
23 * next paragraph) shall be included in all copies or substantial portions
24 * of the Software.
25 *
26 **************************************************************************/
27
28 /**
29 * @file
30 * SRGB translation.
31 *
32 * @author Brian Paul <brianp@vmware.com>
33 * @author Michal Krol <michal@vmware.com>
34 * @author Jose Fonseca <jfonseca@vmware.com>
35 */
36
37 #ifndef U_FORMAT_SRGB_H_
38 #define U_FORMAT_SRGB_H_
39
40
41 #include "pipe/p_compiler.h"
42 #include "u_math.h"
43
44
45 extern const float
46 util_format_srgb_8unorm_to_linear_float_table[256];
47
48 extern const uint8_t
49 util_format_srgb_to_linear_8unorm_table[256];
50
51 extern const uint8_t
52 util_format_linear_to_srgb_8unorm_table[256];
53
54
55 /**
56 * Convert a unclamped linear float to srgb value in the [0,255].
57 * XXX this hasn't been tested (render to srgb surface).
58 * XXX this needs optimization.
59 */
60 static INLINE uint8_t
util_format_linear_float_to_srgb_8unorm(float x)61 util_format_linear_float_to_srgb_8unorm(float x)
62 {
63 if (x >= 1.0f)
64 return 255;
65 else if (x >= 0.0031308f)
66 return float_to_ubyte(1.055f * powf(x, 0.41666f) - 0.055f);
67 else if (x > 0.0f)
68 return float_to_ubyte(12.92f * x);
69 else
70 return 0;
71 }
72
73
74 /**
75 * Convert an 8-bit sRGB value from non-linear space to a
76 * linear RGB value in [0, 1].
77 * Implemented with a 256-entry lookup table.
78 */
79 static INLINE float
util_format_srgb_8unorm_to_linear_float(uint8_t x)80 util_format_srgb_8unorm_to_linear_float(uint8_t x)
81 {
82 return util_format_srgb_8unorm_to_linear_float_table[x];
83 }
84
85
86 /**
87 * Convert a 8bit normalized value from linear to srgb.
88 */
89 static INLINE uint8_t
util_format_linear_to_srgb_8unorm(uint8_t x)90 util_format_linear_to_srgb_8unorm(uint8_t x)
91 {
92 return util_format_linear_to_srgb_8unorm_table[x];
93 }
94
95
96 /**
97 * Convert a 8bit normalized value from srgb to linear.
98 */
99 static INLINE uint8_t
util_format_srgb_to_linear_8unorm(uint8_t x)100 util_format_srgb_to_linear_8unorm(uint8_t x)
101 {
102 return util_format_srgb_to_linear_8unorm_table[x];
103 }
104
105
106 #endif /* U_FORMAT_SRGB_H_ */
107