24bpp -> monochrome?

Hi there,

I'm trying to write an application that gets a bitmap from a scanner, then saves the image. The scanning works fine, problem is, I only want a monochrome image but the TWAIN package is returning a 24 bpp bitmap (albiet in the black & white I requested, yippie).

Does anyone know how I can take this 24 bpp bitmap and make it monochrome?

I know it sounds simple but I've been pulling my hair out. I suspect there's a way to use the BitBlt API call or something similar, but I haven't used these before.

Anyone's help is greatly appreciated, even if it's just a link to some documentation..

Thanks again,

Mike