Re: [SLE] How to avoid copying/scanning printed paper ?

On Sat, 2005-02-19 at 23:01, Carlos E. R. wrote:

It must be a special watermark designed to interfere with the scanner matrix. The document can be scanned, but the quality is bad, and OCR does not work. The design is most probably proprietary.

You can experiment with colors. If you make a raster image with bars 5 mm spaced, in light orange, and ordinary text grey, there is no problem in normally reading it, but when scanning or copying (BW) it, the orange background will become foreground. And OCR will certainly fail. Hans