Cover Art Colors Reverse in iTunes

I just added cover art to a couple of Maria Schneider albums I purchased on Artistshare. When you buy an album on Artistshare, it comes with CD booklets and trays in pdf format. Using Acrobat Standard 8.1 I cropped the cover art out of the pdf, saved as a jpg file and then added the cover art using MP3Tag. The cover art displays correctly in the MP3Tag program. However, iTunes displays the cover art with all of the colors reversed, like a color negative (Blue is now chartreuse, etc) Does anyone have any idea as to why this could be happening?