diff options
Diffstat (limited to 'source/blender/blenlib/intern/arithb.c')
-rw-r--r-- | source/blender/blenlib/intern/arithb.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/arithb.c b/source/blender/blenlib/intern/arithb.c index a366862d064..dd9c76d9172 100644 --- a/source/blender/blenlib/intern/arithb.c +++ b/source/blender/blenlib/intern/arithb.c @@ -3413,6 +3413,66 @@ void rgb_to_hsv(float r, float g, float b, float *lh, float *ls, float *lv) *lv = v; } +/*http://brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html + * SMPTE-C XYZ to RGB matrix*/ +void xyz_to_rgb(float xc, float yc, float zc, float *r, float *g, float *b) +{ + *r = (3.50570 * xc) + (-1.73964 * yc) + (-0.544011 * zc); + *g = (-1.06906 * xc) + (1.97781 * yc) + (0.0351720 * zc); + *b = (0.0563117 * xc) + (-0.196994 * yc) + (1.05005 * zc); +} + +/*If the requested RGB shade contains a negative weight for + one of the primaries, it lies outside the colour gamut + accessible from the given triple of primaries. Desaturate + it by adding white, equal quantities of R, G, and B, enough + to make RGB all positive. The function returns 1 if the + components were modified, zero otherwise.*/ +int constrain_rgb(float *r, float *g, float *b) +{ + float w; + + /* Amount of white needed is w = - min(0, *r, *g, *b) */ + + w = (0 < *r) ? 0 : *r; + w = (w < *g) ? w : *g; + w = (w < *b) ? w : *b; + w = -w; + + /* Add just enough white to make r, g, b all positive. */ + + if (w > 0) { + *r += w; *g += w; *b += w; + return 1; /* Colour modified to fit RGB gamut */ + } + + return 0; /* Colour within RGB gamut */ +} + +/*Transform linear RGB values to nonlinear RGB values. Rec. + 709 is ITU-R Recommendation BT. 709 (1990) ``Basic + Parameter Values for the HDTV Standard for the Studio and + for International Programme Exchange'', formerly CCIR Rec. + 709.*/ +void gamma_correct(float *c) +{ + /* Rec. 709 gamma correction. */ + float cc = 0.018; + + if (*c < cc) { + *c *= ((1.099 * pow(cc, 0.45)) - 0.099) / cc; + } else { + *c = (1.099 * pow(*c, 0.45)) - 0.099; + } +} + +void gamma_correct_rgb(float *r, float *g, float *b) +{ + gamma_correct(r); + gamma_correct(g); + gamma_correct(b); +} + /* we define a 'cpack' here as a (3 byte color code) number that can be expressed like 0xFFAA66 or so. for that reason it is sensitive for endianness... with this function it works correctly |