Hi list, Today I noticed that the bitmap's get-argb-pixels method returns un-premultiplied alpha, even though it internally uses Cairo which uses pre-multiplied alpha.
Looking at the code, it goes out of its way to convert pre-multipled alpha to un-premultiplied alpha. I then need to go out of my way again to convert it back to premultiplied alpha. Which is inefficient and silly. Could we have a method to get at the premultiplied alpha directly? The Cairo folks chose it for a reason; if you want to interpolate between two pixel values then only premultiplied alpha will give the correct result. (See http://www.gimp.org/docs/plug-in/appendix-alpha.html for some discussion on this). I would therefore assume that it might be of wider interest than just me. Thanks, Stephan _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
