In a series of tests I conducted earlier this summer, I discovered that TIFF and JPEG images are displayed differently in Adobe Premiere Pro.
First, it appears the difference is found only on the Mac platform where JPEG files are decoded by QuickTime and TIFF is handled internally within Premiere Pro.
This leads to two important conclusions:
1) For still images, you’ll have best results within Adobe Premiere Pro if you use the TIFF format.
2) Be wary of any QuickTime upgrades installed by Apple’s Software Update feature.
Final Cut Pro users have historically encountered problems whenever Apple releases an update to QuickTime. Since Quicktime is so widely used for rendering photos on the Mac platform, it pays to do a little research before upgrading to a new QuickTime version. This is particularly important given that a new version of Quicktime (QuickTime X) is planned for Snow Leopard.