Consider adding a few (10 or less) how to examples so that users can see how to use the generator with other tools to do what they want. This would help the ascii generator focus on doing image to ascii conversion instead of being bloated with unnecessary features.
These are all open source tools.
For example, a general purpose image editing system (GNU GIMP) or a command line one (imagemagick or netpbm) can be used for most image preprocessing before the ascii generator is used.
Other tools can be used to output the generated ascii text in a variety of formats (e.g., PDFcreator).