+ // converts image's alpha channel to mask, if it has any, does nothing
+ // otherwise:
+ bool ConvertAlphaToMask(unsigned char threshold = 128);
+
+ // This method converts an image where the original alpha
+ // information is only available as a shades of a colour
+ // (actually shades of grey) typically when you draw anti-
+ // aliased text into a bitmap. The DC drawinf routines
+ // draw grey values on the black background although they
+ // actually mean to draw white with differnt alpha values.
+ // This method reverses it, assuming a black (!) background
+ // and white text (actually only the red channel is read).
+ // The method will then fill up the whole image with the
+ // colour given.
+ bool ConvertColourToAlpha( unsigned char r, unsigned char g, unsigned char b );
+