Bug 1056096 - Always prefer higher preview resolution than screen

I don't think it is enough to just compare the heights.  If the preview size was 320, it would match the target height, but with a 4:3 photo aspect ratio, the preview width would by only 427, which is not enough to fill a 480 screen.  So I suggest that you add code above to compute targetWidth as well as targetHeight and compare both dimensions.