Stereograms
My brother and I loved our Viewmaster when we were kids (I've still got it). Decades later, I bought a lovely stereoview slide of the victorian Cliff House for my San Franciscana collection. Over time, I bought more San Francisco stereoview slides and wrote a SF stereoviews web page to display them. Much later, in early 2011, I realized I could make stereograms without a special camera from pairs of photos taken at slightly offset positions, provided the subject remains stationary. I wrote a program to construct stereograms: from a pair of photos and positioning data, it builds an anaglyph stereogram, a reversed stereogram, or a normal stereogram. It's simpler than you might think.
The Wikipedia stereoscopy article gives general information on stereo imaging. You can view paired images using a stereoscope, or you can combine left/right images into a single anaglyph image and view it using simple red/cyan glasses, or you can view paired images without using any device (freeviewing). There are two ways to freeview: place the images in normal left-right orientation and focus past the image (wall-eyed or parallel viewing), or place the images in reversed right-left orientation and focus in front of the image (crosseyed viewing). Freeviewing is nicely described here, with simple illustrations and good viewing advice; I won't repeat it here.
This page shows a few of my stereograms, as both anaglyph (red/cyan) and reversed (crosseyed) images. I find reversed freeviewing more natural than parallel freeviewing, so I typically do not bother to generate parallel image pairs.
Click on any image to enlarge, then use the back arrow on your browser to return.
To start a slideshow, click here for anaglyph images or here for crosseyed images.
/home/photo/san/2011/110204/.tn/a02.png: not found