A Xerox colour photocopier refuses to reproduce banknotes.
A digital watermark embedded in the image
A pattern of five small yellow, green or orange circles, repeated at different orientations.
Simple integer ratios between the squared distances of nearby circles to be detected by image-processing software
The presence of five of these circles on a page is sufficient for some colour photocopiers to refuse processing
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I think i will add this to all my invoices just for fun!


C:\MONEY\>cd.._