What product - Photoshop Elements or Premiere Elements?
What version - 10 or earlier or 11 and later?
What computer operating system - Windows 7, 8, 8.1, or 10 64 bit?
If your program is Photoshop Elements, you have posted in the wrong forum. Some how your thread got posted in the Adobe Premiere Elements Forum (video editing).
If you question involves Photoshop Elements or its Elements Organizer, please re-post your thread in the Adobe Photoshop Elements Forum
But, the render part of your question sounds like you are in a Premiere Elements project. So, please give details.
If you have Premiere Elements, in what way does you tiff image look worst after Timeline rendering? Do you have the same problem with .psd and .jpg images imported into the Premiere Elements project?
Where were these tif images created? Are they flattened or not flattened before import into the Elements project?
Please review, consider, and give more details.
Add On...Moderators, please do not move this thread out of the Premiere Elements Forum until eduardopr tells us what program is involved in this thread question.