I just photocopied a couple of paystubs to send with a loan application. They’re loaded with security features, including that the photocopy shows the word “void” stamped all over it.
Why does the photocopier see this but I don’t when I examine the paystub?
Photocopiers are insensitive to certain colors which your eyes see just fine. (Typically a pale blue, known as “photo blue”.) The background of the checks are printed in a combination of inks that appear a uniform color, usually brown or green, to your eyes, but the photocopier drops out the blue component in selected areas, making those areas appear lighter and exposing the printed message “VOID”.
It’s called a “Void Pantograph”. The intricate design on the back of the check introduces moire patterns into the image when scanned or photocopied.
I believe pluto is talking about rainbow pantographs which work on a different principle than standard pantographs but are just as effective.
Yeah, I only knew about the one and not the other.
See, even us know-it-alls learn something on the SDMB.
Hold a check next to its photocopy. Look at the photocopy, at the edge of one of the letters of the word “VOID”. (The sharp center potion of the V is probably the best spot.) Look at the check, in the place where that letter ought to be. Hold it REALLY close to your eyes, and you should be able to make out a set of dots in the shape of the letter. There may be some other dots as well, which are there to be part of the background. The contrast between these fots and those dots is so small that our eyes can’t see it at arm’s length, but to the photocopied they are very obvious.