I just got some vr cups and tried out the Cardboard Camera app, but the quality is pretty poor, and it's really intended for panoramas. If you have created stereoscopic (NOT panoramic) images for Google Cardboard that you're proud of, please outline your process.
This question is mostly how to edit two images into one that can be viewed with Cardboard, but if you have tips on equipment to use to take the stereoscopic images in the first place, those are very welcome as well.
I realize there are a lot of options. I welcome them all, and I'll upvote every answer I learn something from, but I personally need a solution that is fairly accessible. I need to be able to do it with one camera, and without having to spend more than a few minutes editing an image (not counting the learning curve). I use Gimp, and have a reasonably good 13MP camera on my phone.
2016 May 5 edit:
Note that this question is specific to Google Cardboard. I should be able to open a viewer app and switch to Cardboard view, including scanning the QR code for the specific Cardboard viewer, and have the stereoscopic image render correctly for that viewer. So probably, just creating a regular JPEG consisting of two images side-by-side isn't enough. What format is right for a stereoscopic image to be compatible? What metadata needs to be on an image for a viewer to recognize it as stereoscopic? What viewer app do you use?
Google's docs mention the "equirect-pano" format, but I don't see any documentation on that at this time. Also, this question is not about 360 panoramas, so if the equirect-pano format is the way to go, how would you represent an image with a 60° span without just leaving most of it black? (FYI, even if compression culls out all those black pixels on disk, the same is not true when the app loads it into RAM, which could cause apps to crash attempting to load high resolution images.)