Home | History | Annotate | Download | only in util 
      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 (at) vmware.com>
     33  * @author Michal Krol <michal (at) vmware.com>
     34  * @author Jose Fonseca <jfonseca (at) 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
     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
     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
     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
    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