diff options
Diffstat (limited to 'lib/pm_gamma.h')
| -rw-r--r-- | lib/pm_gamma.h | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/lib/pm_gamma.h b/lib/pm_gamma.h index 6630e05c..3c48e52e 100644 --- a/lib/pm_gamma.h +++ b/lib/pm_gamma.h @@ -17,8 +17,8 @@ pm_gamma709(float const intensity) { /* Here are parameters of the gamma transfer function for the Netpbm formats. This is CIE Rec 709. - - This transfer function is linear for sample values 0 .. .018 + + This transfer function is linear for sample values 0 .. .018 and an exponential for larger sample values. The exponential is slightly stretched and translated, though, unlike the popular pure exponential gamma transfer function. @@ -26,7 +26,7 @@ pm_gamma709(float const intensity) { float const gamma = 2.2; float const oneOverGamma = 1.0 / gamma; float const linearCutoff = 0.018; - float const linearExpansion = + float const linearExpansion = (1.099 * pow(linearCutoff, oneOverGamma) - 0.099) / linearCutoff; float brightness; @@ -49,9 +49,9 @@ pm_ungamma709(float const brightness) { float const gamma = 2.2; float const oneOverGamma = 1.0 / gamma; float const linearCutoff = 0.018; - float const linearExpansion = + float const linearExpansion = (1.099 * pow(linearCutoff, oneOverGamma) - 0.099) / linearCutoff; - + float intensity; if (brightness < linearCutoff * linearExpansion) |