Is there a maximum allowable image size?
Our image uploaders will resize all images larger than 1MB. We also restrict the dimension size to 1024x768 and convert images to JPG format after the upload process. Because of this, it is possible that even if your image was smaller than 1MB, it could end up with an even smaller file size once it’s in on our servers.
got from here
http://www.auctiva.com/free-auction-software-help/help.aspx#maximum-image-size