Accroding to explainig by Rick Brewster, Paint.NET does not use pre-multiplied color values. So, if i understood correctly, information about colors must be saved even if alpha value is 0. Am i mistake?
Whatever i got strange behavior of Paint.NET.
example 1. create new file -> select color (255,0,0,0) -> :PaintBucketTool: -> :ColorPicker: -> got a (0,0,0,0) in result.
example 2(i used cureves+ plugin because did not find any "native" tool to change alpha value). create new file -> select color (255,0,0,5) -> :PaintBucketTool: -> with help of plugin change alpha value of all pixel to 0 -> :ColorPicker: -> got a (255,0,0,0) in result.
i did not understood. AFAIK plugin only changes pixels' color and storing of color information realized by paint.NET core. So can paint.NET handle color such colors as (R,G,B,0) or paint.NET loose information by handling any color with alpha value = 0 as equal?
sorry for grammar.