@airbum, @gblair
Our ambition with iModeler is to be able to take pictures directly off your camera and do all the necessary image processing (resizing for the web, compression, format, rotation etc) for you..
Because of this, iModeler is designed to work great with your iPhone or Android phone, which should make taking quick photos at your modeling table a breeze. Some other modelers may prefer to pre-process their images in Photoshop etc, and we will of course support that, too.
If for any reason, uploading high-resolution pictures straight from your camera isn't your preferred option, feel free to resize and format images yourself before uploading. A useful hint might be is to resize to 1600px across. This is a "native" resolution of iModeler and whenever you provide an image of such resolution, iModeler will just accept the image as-is, giving you 100% contol over the result.
1280px works too, but I would not recommend going lower than that - higher-resolution images are almost always better for the viewing experience.