Jpegs are a compressed file type - a bit like MP3, so there is some data loss when the file is saved. Tiffs are not saved the same way - there is no loss involved. Having said that if you save a jpeg at level 10 or above in Photoshop or other software the loss is hardly noticeable. If you're storing a lot of files and do a bit of compression at high quality settings then jpegs are fine - they take up a lot less space. I'm just fussy thats all.
...and while Jpegs are known for their space compression , they also compress colours too. I generally save a high quality printable version as a TIFF because it is "loss-less". Not only is spatial detail preserved down to the last pixel, but colour fidelity is also preserved. Jpeg (with anything less than level 10) will wash out or obliterate colour detail at the pixel level. That's another reason for setting the level to 12 always unless you need to save storage.
That's why I was a bit surprised that the site requirement was for Jpegs rather than Tiffs.
...Max
