One company may have just changed printing technology for the better in a way we have never seen.
Ecole Polytechnique Federale de Lausanne (EPFL) has created a technology that allows hidden elements to be injected into an inkjet-printed image, so when a user rotates the image 90 degrees, he or she sees another image underneath.
In a demonstration of the technology's output, EPFL takes an image of a white beach umbrella, which gets a splash of colors when tilted 90 degrees in a sort of holographic effect. EPFL says the technology, which is accomplished through a special printing algorithm and software, can be key in cracking down on counterfeiting of identification documents.
"Elements can only be seen upon rotation," Roger Hersch, of EPFL's Peripheral Systems Laboratory, said in an article published by EPFL. "This rotation effect has never been done before."
The company's algorithm superposes two images during printing, thus creating a print with visible and hidden elements. All it takes is a 90-degree tilt of what's printed to unearth the hidden image underneath.
EPFL described in detail how it accomplished this technology in an excerpt of its article below:
"Printers spray ink as tiny dots into precise patterns, a standard technique called halftoning. Different patterns of cyan, magenta and yellow dots produce a wide range of colors. When the halftone is printed along lines onto metallic sheets, the researchers noticed that the resulting color depends on the viewing angle. This is because incoming light traversing the ink lines cast shadows onto the metallic surface. Ink lines perpendicular to the incoming light create a large shadow and appear as 'strong colors.' Ink lines parallel to the incoming light do not induce a shadow and appear as 'weak colors.' When the print is rotated by 90 degrees, strong colors become weak and weak colors become strong."
Pretty cool, right? This technique opens users up to a whole new world of printing possibilities.
