@alvise wrote:
TW_IMAGEINFO, on the contrary, is exactly the structure containing the parameters that I want to set.
I just want to perform one simple task: scan a B&W letter size sheet at 200 dpi and get the uncompressed data.
Nevertheless, I’m quite sure that you should use a set of Capability negotiation commands. And yes all of your values in TW_IMAGEINFO structure are legitimate, but as I understand TWAIN doesn’t allow to use SET command with this structure.