Thanks Macropod. I already tried turning off all image compression. Unless I'm missing something in that procedure, it didn't help.

I have not tried cropping. Will try when this happens on a square picture.

Another time I get the border artifact is when I use a curved .png image. I like putting in .png images and setting the text wrapping to tight so the text will wrap around the curves of the image. Looks good in print, but this is one of the main ways I get a border artifact on the PDF screen view. Because the png images in these cases are not square, I'm guessing the cropping strategy would not be an option.

Any other techniques I could try?