While reading the BMP file, i can translate them to the following color depth :
1) use the color depth of the BMP file
2) a standard (say 32 bits) whatever the color depth of the BMP and of the screen
3) use the color depth of the screen

NB : Delphi use the resolution of the screen. I think they did so because under windows, if you use the color depth of the screen it work quicker than any other color depth (M$ says so in the API description). using the color depth of the screen seem to me a bad choice because if you want to edit a BMP without displying it, you should be able to work with at least the BMP resolution.

Which solution do think i should use?
P Jean dit Bailleul ()