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I'm reading a relatively old paper (1976). I'm trying to figure out how to interpret the blobs on the micrograph images. Then I see this in the legend:

The stereoscopic pairs of micrographs, produced by tilting the specimen stage, should be viewed with a stereoscopic hand viewer.

I don't have a stereoscopic hand viewer. I have very little idea of what that even is. However, maybe there's software which can create a similar effect? I'm hoping that it might help me have a better understanding of the images.

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There are many options to view stereoscopic image pairs.

  • There are two unassisted methods to view image pairs.

    • Parallel viewing. The images are placed the way they would be with a viewer. The right image is in front of the right eye. Since it's very difficult to separate convergence from focus, I've successfully used this method once. This works only with small images with the centers only a few inches apart.

    • Cross-eye viewing. The right image is placed on the left side. The eyes are crossed so the right eye looks at the right image (which is on the left side). The left eye will look at the left image (which is on the right side). This works for arbitrarily large images, limited by your ability to cross and focus your eyes. This is far easier than parallel viewing, since most people are able to cross their eyes. However, if images are in the wrong order, the effect will be wrong and may be disorienting.

  • If you're viewing digital images, you can try making wigglegrams. They are basically just animated images that flip between views. If you don't need the GIFs, you can just switch between images in an ordinary image viewer. With prints, you can try making a flip book.

    wigglegram example

  • You can try creating anaglyphs. They require using special red/blue or red/cyan glasses.

    anaglyph example

  • With the advent of Google Cardboard, phone VR viewers have become very common. I have even seen them in discount clothing stores, dollar stores, and thrift stores. You would still need to find an app to display the images.

    • There are viewers that are little more than lenses in a frame. If you'd prefer this type of viewer, you can try adding search terms "compact", "portable", "folding", etc.

    • Strong reading glasses may work. Most Google Cardboard viewers use planoconvex lenses, which function the way reading glasses do. (I haven't tried though.)

    • Loreo makes viewers that predate Google Cardboard. They use prisms instead of planoconvex lenses, so might work better with larger images.

  • Special hardware, glasses, etc.

    • There are some televisions and displays that allow free viewing stereoscopic pairs. Some notable devices with 3D displays:

    • There are systems that use shutter glasses to alternately block each eye while flipping between images.

Software that may be of interest...

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    \$\begingroup\$ Wow! I never thought of this... The wigglegram actually preserves the perception of depth, even when viewed with only one eye! This would be of huge benefit for people with vision defficiencies. \$\endgroup\$
    – virolino
    Oct 16, 2020 at 12:33
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    \$\begingroup\$ @virolino If you pay atention to people with monocular vision, you may notice that some of them shift their weight from leg to leg. It's an unconscious attempt to compensate for lack of stereo vision. \$\endgroup\$
    – xiota
    Oct 16, 2020 at 12:45
  • \$\begingroup\$ :O another wow! I do not have extensive experience with such people, so I did not notice the behavior. But it makes sense now \$\endgroup\$
    – virolino
    Oct 16, 2020 at 12:47
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    \$\begingroup\$ That's impressive. So just pulling things together for the sake of anybody who's not a computer nerd, you could scan a pair of side-by side stereoscopic images and combine them into a two-frame GIF as a wigglegram. Or you could scan an anaglyph, separate the red and the green into monochrome frames, and then similarly present it as a two-frame GIF. \$\endgroup\$
    – Mark Morgan Lloyd
    Oct 17, 2020 at 12:45
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One of the simplest methods of emulating stereo viewing also requires no special software to view or create: animated GIF. Most full-featured image editors can create animated GIF files from a set of images; some will automate the process more, but it's simple enough to do manually without undue effort.

This works both with conventional stereo pairs and with multi-image like the Nimslo camera (intended for lenticular stereo prints). The images are pasted into an animated GIF file in a manner that causes them to display for a short time (.2 to .5 seconds per frame works well) in an order that seems to "tilt" the image right to left and back again. The GIF is then set to loop continuously, and any software that can display GIF (which is virtually everything that can view images) will show the image in a way your brain will interpret as 3D.

This works on phones, tablets, desktop or laptop computers, and even smart TVs -- anything that can display a GIF.

Alternatively, for printed images, you may be able to train yourself to "free view". This is a method of viewing stereo pairs without a viewer. It requires fooling your visual system into decoupling focus from convergence, to let you focus close while letting your eyes become parallel, as if viewing a distant object.

There are a number of tricks for this -- the simplest is to hold the page with the image with something distant behind it. Look at the distant object, and move the page until the two images overlap (or ideally, fully fuse), then switch your gaze to the fused/overlapped images and let them come into focus without losing fusion. This is actually what a stereo viewer is doing, but the use of lenses makes it much easier.

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The method I use to view stereoscopic images - where two prints are side by side, is by:

  1. placing the image a foot or two away then.
  2. place my hand vertically as a divider - thumb in front of my nose, all fingers up, between my eyes
  3. looking at the picture - move closer / further (depends on dimensions) to permit each image to overlap... when they overlap it's 3D. I suppose a paper or envelope would work as well as a hand.

For example, after googling for "produced by tilting the specimen stage" ... I found some nucleosomes and tried it with this article, pdf pg. 10, (book pg. 304). https://cyberleninka.org/article/n/175504.pdf from my laptop screen at 75% zoom, then on an external 24" monitor also at 75% zoom... sat back some 50cm / 20" away, was clear and 3D.

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There is software that creates a similar effect:- virtual reality.

A stereoscope will present each eye with a different image to give the illusion of 3D. This is exactly what VR does.

However, you would need to scan your images and show them to each eye in a VR headset.
Unless you can get them into an old Nintendo 3DS, which simulated 3D on a 2D platform.

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  • \$\begingroup\$ To get the images to display in 3D on a 3DS, the left and right images need to have the same main filename but a different extension – I can't remember what the extension is, though. \$\endgroup\$
    – wizzwizz4
    Oct 16, 2020 at 18:16
  • \$\begingroup\$ Apparently I was wrong; you only need the .mpo file, which consists of both images concatenated together. \$\endgroup\$
    – wizzwizz4
    Oct 18, 2020 at 12:03
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There is a possible low-tech solution which I saw used in Edinburgh's Camera Obscura.

Simply print out the images side be side (no gap between them, identical sizes) and put a (mountain) fold down the middle. Put your nose against the fold. Voila! Each eye sees a different image. No crossing eyes or headaches involved.

In the display in the camera obscura, the images are presented on the corners of a pillar and people put their noses against the corner of the pillar. There may be some perspective fuzziness, but there has to be a cost for such a simple solution.

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Stereoscopy relies on a single phenomenon… each eye can only see one of the two images.

The only economical solution I can think of, short of building your own box with lenses, would be to scan the image then display it on your phone using something like Google Cardboard.

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