To my surprise I perceive a somewhat fleeting and weak impression of rotation when simply moving my head relative to the screen. WFL On 4/10/15, Simon Plouffe <simon.plouffe@gmail.com> wrote:
Hello, the eye effect of the figure remains even if we print the page on paper. Also, for currencies they use Guilloche patterns to avoid copy, these patterns where made at the time with a mechanical device. now they are computer generated I presume, Also, the Guilloche patterns where superimposed one over the other : quite difficult to reproduce correctly on old printing machines and now with scanners the difficulty resides in the Moiré effect made by the scanner over the Guilloche patterns. The Guilloche patterns are not Moiré BUT if you scan with scanner a banknote then it will create ones ... And also it will connect on the internet and reveal information about you too, the same if you open a scanned banknote with Photoshop it will do the same : I know I tried it ! , I was making big 'fake' gray scales 100$ canadian bills for my students : giving them 1 if the answer was correct, they found the game stupid at first but with time they enjoyed that little game.
Best regards, Simon Plouffe _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun