King Quark hath returneth!

[Joe]

I do use JPEG in ID - most of the time, the naked eye can't tell anything bad is happening. The exception is if there is text in any of the images - you can usually see the JPEG artifacts around the letters, so in those instances I'll switch to ZIP.

Most of the time you won't see any difference but I have had images before that was noticeable to the naked eye. Usually when you do see it is when the images have already been saved with jpeg compression. To me it isn't worth saving a few bytes to always be assured of not losing any quality when creating the PDF.