GIMP Version: 2.8.14
Operating System: Linux
GIMP Experience: Intermediate Level

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I'll soon be making paperback covers from digital photos. In a tutorial it says:

A tiff file will have better resolution than a jpg, so if you’re creating your own file, or an artist is supplying it, see if they can get you a tiff.

Okay, I've always avoided .tiff files in the past because they're more expensive to purchase and they tend to be too big for my needs and their file size is huge, which is bad for ebooks because you're charged 'delivery costs' for the total file size of the ebook, which of course includes the cover image.

But now I've been reading about .tiff vs. .jpg and I have questions.

I know .tiff is lossless and .jpg is lossy. But if when I reduce a .jpg I always use the 100% save option am I really losing that much image quality?

When I reduce a .tiff I lose no image quality?

And if lossless is the issue why do printers want .tiff files and not .png files?

From what I can tell the real reduction in image quality comes from frequent reductions of the .jpg files and often at less than the 100% setting.

But here's another question:

I buy a .jpg. I work on it in GIMP as an .xcf. Then when I'm done I export it as a .tiff file. So that makes it lossless, right? And with print paperbacks they're not concerned with file size so that may be the way to go.

Can .tiff files be compressed?

And are there any other advantages to .tiff files (over .jpgs) (in terms of purchasing a .tiff instead of a .jpg with the ultimate goal of creating a paperback cover)?

Thanks

I know .tiff is lossless and .jpg is lossy. But if when I reduce a .jpg I always use the 100% save option am I really losing that much image quality?
No, not that much

When I reduce a .tiff I lose no image quality?
If by "reduce" you mean scaling down, yes, you lose image quality, but you don' t need more pixels than what is required for a paperback size a 300DPI.

And if lossless is the issue why do printers want .tiff files and not .png files?
Because they know how to handle them. TIFF has been invented for the print industry.

From what I can tell the real reduction in image quality comes from frequent reductions of the .jpg files and often at less than the 100% setting.
JPEG isn't an editing format, it is an "usage" format (like PDF... do you edit your docs in PDF or do you go back to the .DOC). So yes, repeated editing degrades it (but more slowly than most people think), but it a professional workflow you don't deal with a JPEG until you output something for the e-publishing.

I buy a .jpg. I work on it in GIMP as an .xcf. Then when I'm done I export it as a .tiff file. So that makes it lossless, right? And with print paperbacks they're not concerned with file size so that may be the way to go.
No further losses, but some loss already occurred when the initial image was converted to a JPEG that you can purchase.

Can .tiff files be compressed?
Yes, they can be zipped, and one of the multiple TIFF format is actually compressed (with losses...).

And are there any other advantages to .tiff files (over .jpgs) (in terms of purchasing a .tiff instead of a .jpg with the ultimate goal of creating a paperback cover)?
Depends on JPEG quality and what you do with the image. JPEG compression artefacts can make image editing more difficult.

Wow! Thanks so much for all the great info, ofnuts! A couple of follow-up questions.



So if I have enough pixels to make a 300 DPI paperback cover it really doesn't matter if it's a .jpg or a .tiff?



So my workflow is: jpg into GIMP, work on the file as an xcf. Then eventually export it as a jpg. So I have no editing degrades while editing in xcf?

Yes to both.

Cool. Thanks so much.