1) render string at large font size to monochrome bitmap 2) loop over all pixels in the bitmap, writing spaces or asterisks depending on bit value You can als

1) render string at large font size to monochrome bitmap 2) loop over all pixels in the bitmap, writing spaces or asterisks depending on bit value You can also render anti-aliased to grayscale and use blacker/whiter ASCII characters. Many languages have libraries/support for #1, and for accessing individual pixels in a bitmap. If you have that, #2 is trivial. The most difficult part may be to make sure to pick a font that allows you to do whatever you want to do with the ASCII art.