When looking at graphics, the home page css theme that is being used is set at 650 pixels. That means that the maximum width of the home page main window is 650 pixels. Items that are uploaded with the NexGen Gallery (which shows pictures, under the Photos menu selection) are limited to 800 pixels in width. The upload program in general does some “crunching” in order to make the images a bit smaller, but you may want to decide the width of your picture before performing the upload. In general “scaling” occurs which shrinks the picture. Sometimes however, you end up getting the image cropped, and an essential portion of the picture will be lost. IN GENERAL the upload program will let you change which happens. Thumbnail pictures are generally created automatically and will crop the image.
Good luck and I hope this is helpful.