diff options
Diffstat (limited to 'source/blender/blenlib/intern/math_color.c')
| -rw-r--r-- | source/blender/blenlib/intern/math_color.c | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/math_color.c b/source/blender/blenlib/intern/math_color.c index 8f5366b6317..3627b38a091 100644 --- a/source/blender/blenlib/intern/math_color.c +++ b/source/blender/blenlib/intern/math_color.c @@ -30,7 +30,11 @@ #include <assert.h> +#include "MEM_guardedalloc.h" + #include "BLI_math.h" +#include "BLI_rand.h" +#include "BLI_utildefines.h" void hsv_to_rgb(float h, float s, float v, float *r, float *g, float *b) { @@ -480,3 +484,79 @@ void rgb_byte_set_hue_float_offset(unsigned char rgb[3], float hue_offset) rgb_float_set_hue_float_offset(rgb_float, hue_offset); rgb_float_to_byte(rgb_float, rgb); } + + +/* fast sRGB conversion + * LUT from linear float to 16-bit short + * based on http://mysite.verizon.net/spitzak/conversion/ + */ + +float BLI_color_from_srgb_table[256]; +unsigned short BLI_color_to_srgb_table[0x10000]; + +static unsigned short hipart(const float f) +{ + union { + float f; + unsigned short us[2]; + } tmp; + + tmp.f = f; + +#ifdef __BIG_ENDIAN__ + return tmp.us[0]; +#else + return tmp.us[1]; +#endif +} + +static float index_to_float(const unsigned short i) +{ + union { + float f; + unsigned short us[2]; + } tmp; + + /* positive and negative zeros, and all gradual underflow, turn into zero: */ + if (i<0x80 || (i >= 0x8000 && i < 0x8080)) return 0; + /* All NaN's and infinity turn into the largest possible legal float: */ + if (i>=0x7f80 && i<0x8000) return FLT_MAX; + if (i>=0xff80) return -FLT_MAX; + +#ifdef __BIG_ENDIAN__ + tmp.us[0] = i; + tmp.us[1] = 0x8000; +#else + tmp.us[0] = 0x8000; + tmp.us[1] = i; +#endif + + return tmp.f; +} + +void BLI_init_srgb_conversion(void) +{ + static int initialized= 0; + int i, b; + + if (initialized) return; + initialized = 1; + + /* Fill in the lookup table to convert floats to bytes: */ + for (i = 0; i < 0x10000; i++) { + float f = linearrgb_to_srgb(index_to_float(i))*255.0f; + if (f <= 0) BLI_color_to_srgb_table[i] = 0; + else if (f < 255) BLI_color_to_srgb_table[i] = (unsigned short)(f*0x100+.5); + else BLI_color_to_srgb_table[i] = 0xff00; + } + + /* Fill in the lookup table to convert bytes to float: */ + for (b = 0; b <= 255; b++) { + float f = srgb_to_linearrgb(((float)b)*(1.0f/255.0f)); + BLI_color_from_srgb_table[b] = f; + i = hipart(f); + /* replace entries so byte->float->byte does not change the data: */ + BLI_color_to_srgb_table[i] = b*0x100; + } +} + |