The magic lens: refractive steganography

1Disney Research Zürich 2ETH Zürich 3University of Montreal

In ACM Transactions on Graphics (Proceedings of SIGGRAPH Asia), 2012
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We automatically design and manufacture magic lenses to warp source images into meaningful target images. Here we photograph a source image (far left) viewed through a manufactured lens with 32x32 facets (left), resulting in four images depending on the lens' rotational orientation atop the source.
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Abstract

We present an automatic approach to design and manufacture passive display devices based on optical hidden image decoding. Motivated by classical steganography techniques we construct Magic Lenses, composed of refractive lenslet arrays, to reveal hidden images when placed over potentially unstructured printed or displayed source images. We determine the refractive geometry of these surfaces by formulating and efficiently solving an inverse light transport problem, taking into account additional constraints imposed by physical manufacturing processes. We fabricate several variants on the basic magic lens idea including using a single source image to encode several hidden images which are only revealed when the lens is placed at prescribed rotational orientations or viewed from different angles. We also present an important special case, the universal lens, that forms an injunction with the source image grid and can be applied to arbitrary source images. We use this type of lens to generate hidden animation sequences. We validate our simulation results with many real-world manufactured magic lenses, and experiment with two separate manufacturing processes.

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Marios Papas, Thomas Houit, Derek Nowrouzezahrai, Markus Gross, Wojciech Jarosz. The magic lens: refractive steganography. ACM Transactions on Graphics (Proceedings of SIGGRAPH Asia), 31(6), November 2012. 
@article{papas12magic,
    author   = {Papas, Marios and Houit, Thomas and Nowrouzezahrai, Derek and Gross, Markus and Jarosz, Wojciech},
    title    = {The Magic Lens: Refractive Steganography},
    journal  = {ACM Transactions on Graphics (Proceedings of SIGGRAPH Asia)},
    volume   = {31},
    number   = {6},
    year     = {2012},
    month    = nov,
    doi      = {10/kdc},
    keywords = {steganography, cryptography, image morphing, lens fabrication, novel display devices}
}
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