Attention: 3DS screenshots on Miiverse that you view in the browser ARE actually in 3D.
More specifically, they conform to the .mpo format, which is basically just two .jpgs stored in one file. Your browser can't display 3D pictures, so it only shows you one of the two .jpgs.
But it is possible to extract them!
I'm done with my life, adios.
This pic in 3D slayed my whole existence.
https://miiverse.nintendo.net/posts/AYQHAAABAAC_UqFITBF2rA
Cross-eye viewing means crossing your eyes until the pictures line up. Parallel viewing is what you do when you look at a Magic Eye picture, it's sort of unfocusing your eyes and looking "past" it. Some people can only see one or the other; I can only see it cross-eyed.
The difference is only a matter of how the pictures are oriented. If the 3D looks inverted, then you need to swap the left and right pictures.
Instructions for creating cross-eye/parallel 3D pictures:
- Save the screenshot from Miiverse as the instructions in the OP say.
- Change the file extension of the image from .jpg to .mpo. You don't need to resave the pic or anything, just change the extension.
- Download Stereo Photo Maker:
http://stereo.jpn.org/eng/stphmkr/
- Open Stereo Photo Maker and click File -> "Open Stereo Image..." Choose your .mpo file. You should now be looking at two nearly identical images.
- Click File -> "Save Universal Freeview L-R-L."
Make sure to crank the image quality slider all the way up! Choose where to save your picture. Upload to imgur and post at GAF!
Please put this in the OP if you feel it is appropriate.
