I felt that my resume/curriculum vitae needed a quick way for people to get in touch with me, so I generated a QR code to encode my contact information. The QR code is scannable using a barcode reader app on most modern smartphones and will automatically pop up with my email and website contact information. I wanted the code to stand out, so, rather than embedding a logo/image into the center, I decided to go the psychophysical route and create a stereogram!
To view, focus eyes behind the image (diverge) or in front (converge, cross-eyed) so that the two images combine into one.
The stereogram was created by shifting a surface of pixels to the left in one image and right in the other (see an example in Wikipedia’s Random Dot Stereogram entry). When the two images are perceptually fused, you perceive the shift as a change in depth of the surface (more info in Wikipedia’s Autostereogram entry). The shift needed to be small enough that the codes would still be scannable (see Wikipedia again), but provide a convincing amount of depth.
I’ve also attached an animated version (also scannable!) using the left and right images as frames (See Lee (1970) Binocular stereopsis without spatial disparity for additional discussion):