png files

[Linux for blind general discussion]

What you're looking for is Ocular Character Recognition, OCR for
short, software. The two available for Linux I know of are Tesseract
and Cuneiform. I haven't much experience with Tesseract, but its been
a while since I used Cuneiform and if I remember correctly, Cuneiform
produced gibberish about as often as anything useful and had to be
installed from the Universe repository under Debian. I also remember
reading somewhere that its recommended to do certain manipulations
with imagemagick before feeding an image to OCR, but I forget the
details.

Sorry I'm short on specifics, but hopefully this gives you enough of a
starting point to find useful tutorials for getting the most out of
OCR.

-- 
Sincerely,

Jeffery Wright
President Emeritus, Nu Nu Chapter, Phi Theta Kappa.
Former Secretary, Student Government Association, College of the Albemarle.