importing from your pc
Not all image formats and resolutions will be recognized by your Nintendo 3DS™ when attempting to import a photo from your PC to your SD card. Nintendo does not have an official procedure for adding photos to your SD card, but we have found the following procedures and considerations effective:
Image must be of JPEG formatRename the image so that it begins with HNI_ followed by four digits. As an example, HNI_1234.jpgThe width of the image cannot exceed 400 pixelsThe height of the image cannot exceed 240 pixels
Colors! 3D offers three canvas sizes to work with. If you are trying to import a photo to match the size of your canvas, here are the dimensions you want to format your reference photos:
Widescreen: 400 x 240Landscape: 320 x 240Portrait: 180 x 240
After you've found and formatted your photos, insert your SD card into your PC, and at the root of your SD card, navigate to to DCIM folder. If you've used the Nintendo 3DS Camera application before, there should be one or more more sub-folders with images in them.
Drop your photos in with those other photos and the next time you try to import a reference image in Colors! 3D, you should see your newly added photos for selection.