With Stereoscope, you can view side-by-side stereographs in true 3D, without crossing or relaxing your eyes.

How to use Stereoscope

To view a single stereograph, pinch and hold on the image, then Share, and choose Stereoscope on the share sheet.

To view multiple stereographs, first save them to your Photos Library — it's a good idea to create a new album. Then, open Stereoscope and press the “Load from Photos Library”button to choose them. In Stereoscope, use the arrows beside the photos to navigate.

Alternatively, you can copy a stereograph, then press "Load from Clipboard" in Stereoscope. This is a quick way to view an image that's on your Mac.

Most stereographic images are in the parallel (left-right) format, but if the image looks wrong, press "Swap L/R" to toggle to the cross-eye (right-left) format.

Images will be cropped automatically to focus on the stereo photo within the image. However, not all images will be interpreted correctly. If the image still doesn’t look right, adjust the crop, offset and/or rotation sliders at the bottom of the window.

Many historical and modern stereographs are available online. Try some of these images to start:

https://www.londonstereo.com/3-D-gallery1.html

The image shown in the screenshots above are in the public domain, from the Getty Museum's collection: https://www.getty.edu/art/collection/search?object_type=Stereograph&open_content=true&images=true

More info

1. Most modern stereographic images do not include frames, or use frames of equal width on both sides. These should work seamlessly.

2. Older stereographs usually include a frame, and Stereoscope will try to crop out the frame for you.

3. Please also note that not all stereo 3D images have been created in the same way, and some images simply may not look good. If an image looks strange or causes eye strain, try reloading with the other mode (Parallel or Cross-Eye). However, if the two images are offset vertically, pre-processing in an image editor may be necessary.

4. Stereoscope is only a viewer, and nothing is ever saved. Stereoscope does not convert images into true Spatial format for viewing in the Photos or Files apps.