Using 640X480 is the best resolution for taking images and importing images. Other resolutions can be used but should be multiples of 640X480, for example, 1280X960, 2560X1920. If resolution is not multiples of the standard 640X480, there is the possibility of incorrect compression of images leading to oval-horizontal pupil and false positives.

To understand more about correct image resolutions, please refer to the sample chart below: