Making text difficult for OCR?

[Ken Brown]

Write by hand. Change your handwriting style part-way through.

The other option, which will take you *much*  longer to set up, is to
use contrasting colours of background and text, but make them change,
like those cards for detecting colour blindness. So the background would
be a smoothly changing mess of colours and the text would, in effect, be
a mask into a different smoothly changing mess of colours. If you
randomised it you could get stuff where the chance of suitable contrast
was high enough that enough text had a sharp enough edge to read, but
enough of it was blurred to cause confusion to OCR. Not to mention
migraines to humans.

If the colours were chosen carefully, off-the-shelf OCR would also be
confused because the contrast of the edges would be colour, not
intensity. OTOH it would be circumventable by enhancing colour contrast
then switching to monochrome & enhancing edges. Anything you can do in
10 minutes with Paint Shop Pro is probably doable by the Men In Black
sooner or later. 

To be honest, the whole thing is likely to be worth more as a tool for
generating retro-Op Art or Pop Art images.  Write the code & pray for a
revival of free festivals. For obfuscation, stick to handwriting. 

As an afterthought, the experts in this must be the people who print
banknotes. Real ones, I mean, not your boring US green ones that are all
the same size and colour so foreigners can't tell them apart and you
have to employ millions of Secret Service agents to stop forgers. I bet
the Bank of England go on about it on their website.

Ken Brown

"Dr. Evil" wrote:
 
> I have a question for you c'punks.  If you wanted to generate some
> bitmaps of text which would be difficult or impossible to OCR, but not
> too difficult for humans to read, how would you do that?  Basically, I
> want to create GIFs of text which can't be OCRed in a reliable way.


pardon me for top-posting...