I am trying to create a piece of software that can be used to create VERY large (10000x10000) sized bitmaps. All I need is something that can work in monochrome, since the required output is a matrix containing details of black and white pixels in the bitmap. The closest thing I can think of is a font editor, but the size is a problem.

Is there any library out there that I can use to create the software, or will I have to write the whole thing from the start?