Flipping Page and Low/High Rez Images

I purchased the full WP version of Flipping Book app for WP.. The FAQ from developer mentions the technique of using a low rez image for the animation and a higher rez image for the enlargement in order to balance speed of loading for the animation. I cannot find a way to do this. I can load a high rez image and notice that it is scaled and shows at lower rez for the animation and then I can see the higher rez when enlarge feature is used but the FAQ would lead you to think that another technique is possible.

By the way, the developers are not very responsive, even though I am a registered paid user. =(

All help is appreciated!