On 9 Aug 2001, 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. I've thought about some things: I can put in noise pixels, I can blur the text, I can rotate, shear, and otherwise distort it.
Some ideas: Start with a highly ornate script font. Anti-alias. Try a font with lots of gaps and other topology breaking features. Pluck out a decent perceptual model from one of the better image compressors and try doing maximum modifications beneath a given perceptual error bound. Low contrast, with information encoded in the hue channel. (Dead trees: Use a colorless, fluorescent ink, or a combination of such inks to throw off the scanner. Print your stuff on extremely heat and/or light sensitive paper.) Sampo Syreeni, aka decoy, mailto:decoy@iki.fi, gsm: +358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front