Use the optimization wizard to save the file, and then click on the customize button when you see the choice to save as a quality file or a smaller file window ( the one with the slider ) Then click on the Partial tranparency tab and try playing around with the pixel settings in there. I think what is happening is it is converting the edge of your picture to white because there may be just a few pixels that didn't or don't get erase fully and it's dithering them to the closest color and causes your picture framing issue.