Luminous Landscape Forum
The Art of Photography => The Coffee Corner => Topic started by: PeterAit on September 11, 2018, 11:43:33 am
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I am hoping one of you can explain this to me. I was scanning a legal document and the resulting scanned image had the word VOID all over it. But the document itself did not, even when holding it up to a bright light. I am curious as to how a document can be created that has this sort of hidden text that comes out only in scans.
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I am hoping one of you can explain this to me. I was scanning a legal document and the resulting scanned image had the word VOID all over it. But the document itself did not, even when holding it up to a bright light. I am curious as to how a document can be created that has this sort of hidden text that comes out only in scans.
Is this what you have?
http://www.highsecuritypaper.com/security-paper-information.html
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I am hoping one of you can explain this to me. I was scanning a legal document and the resulting scanned image had the word VOID all over it. But the document itself did not, even when holding it up to a bright light. I am curious as to how a document can be created that has this sort of hidden text that comes out only in scans.
Hi Peter,
Try scanning it with a higher resolution. These patterns are usually created by aliasing artifacts between the printed raster and the sensor pixels.
Cheers,
Bart
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I had never heard of this, but doesn't it seem like something that could be part of a good plot twist in a legal thriller?
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Every commercial check I scanned in for the last 6-10 years had the same security built in.
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Every commercial check I scanned in for the last 6-10 years had the same security built in.
It will be interesting to see how the latest system for paying in cheques in the UK copes with that. The idea is, using your bank's phone app, you photograph the cheque. That's then it: it's paid in. No going to the bank, no queuing to use the ATM, no queuing at the window.
I can't wait.
Jeremy
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It is possible that only scanners (and copiers) are affected by this. Try photographing this document with a camera and see if the pattern is still visible.
I had a similar pattern on a Japanese Language Proficency Test certificate with the word "copy" and oddly enough, it would not appear on a photo of the document (due to the bayer matrix?).
Cheers,
Fabien