I dont know what is on your machine, but mine cacaview and asciiview works with bmp, jpg, png files without problems.
About ascii limitation in cacaview: You can zoom in/out image to make output looks more familiar to you
Zooming comes very handy when reading pdf documents via cacaview. (use pdftoppm for converting pdf to images - comes with xpdf)
For ps/pdf/dvi you can convert pages to images (specify DPI for custom resolution) and then view images via zgv, or if your OS doesnt have framebuffer via cacaview.
If that doesnt help you, you still can print pdf/dvi/ps documents and read them once they come out from printer
Maybe I will switch from kpdf+X11 to pdftoppm+cacaview/zgv after this post ...