Changing the size of your uploaded images will not cause problems with animations and the "Recent Activity" window. However, that being said, when an animation is created, the software checks to see if the uploaded images for the given request are all the same size. If they are not all the same size, they must be converted to the same size. Since the software cannot know ahead of time what size should be used, it converts all images to a uniform size of 320 pixels wide by 240 pixels high. If your incoming images are not of the same proportion, you may notice some distortion. In general, we recommend keeping the uploaded images a fixed/constant size (at least for each day).