As you know, the cameras on the Nintendo 3DS are pretty bad. Here is how to
use a LUME PAD 2 to make pictures for it.
- take pictures on LUME PAD 2
- run StereoPhot6oOptimizer app (from https://share.duttke.de/stereo-photo-optimizer.apk)
- click white spot at bottom
- select picture from thumbnails
- click Add
- select Export image
- transfer picture from Pictures directory to Mac/PC
- run SPM program on Mac/PC (from http://stereo.jpn.org/eng/stphmkr/)
- select File → Open Stereo Image
- select Edit → Resize
- set to 640 by 400
- select File → Save MPO File
- select File → save Left/Right Images
- rename MPO file to HNI_00xx.MPO (xx is a number of your choice)
- rename left file to HNI_00xx.JPG (use same number here)
- copy those files to the 3DS SD card in /DCIM/101NIN03 directory
- view with picture/camera program
I agree it is a lot of steps on several systems, but I haven’t found something easier (yet).