Where the average value of the upper channels is brighter than 50% (32768), value (essentially, brightness... but not exactly. Because hue and saturation remain constant, no aberrant color shifts occur) is increased. Where the average value of the upper channels is darker than 50%, value is decreased. The range is zero to 200%.
Where the higher layer is partially transparent, the result is mixed with the lower layer composite in a manner proportional to the amount of transparency.
Please consider supporting my iToolBox development efforts with a small PayPal donation. |