JPG Compression and IQ

I'll apologize in advance as I'm sure this has been asked a ton of times but I've not come up with a search that gives me what I'm looking for without a billion other extraneous threads . . .

I'm taking images for a client that were processed out from LR at 100%. I need to make them more upload/download friendly. Fastone Photo Resizer is my preferred non-LR compression tool. 90% quality gets me plenty of compression and, of course on my monitor, the before and after look identical. But what about prints maybe as large as 16x24? Will 80-90% compression have any perceptible impact on IQ?

Thanks.

When you say "80-90% compression", do you actually mean "80-90% Quality"? They are the opposite of each other!

Plenty of people will say use a Quality of, say, 90 because there is no noticeable difference compared to 100, other than the larger file size at 100. That's a decent approach for printing up to larger sizes.

For viewing on a monitor/Web, my quality in Lightroom is just set to 70. I don't see anything troublesome from it. I just prefer a higher quality for prints, although I rarely use an outside printer. I have tons of prints that I've done here directly from Lightroom, but of course there is no jpeg compression used!

So you'll know, the places where jpeg compression "artifacts" do show up are areas of what should be a smooth gradient of tones, such as a clear sky. I have prints from old jpegs that, when you look closely show that type of artifact. So, don't be carless with your jpeg quality, especially with that type of scene. But like I said, I toss 70-quality images up to the Web with no complaints!

Yes, I'm actually saying it backwards; 80-90% quality.

Thanks for the insights, Tony.

Have a read: http://regex.info …room-goodies/jpeg-quality

100% is totally unnecessary and pointless. Even 80% is probably unnecessary. 60-70% is fine.

I use Q10 in Photoshop, and that's overkill. Q8 is fine. I forget how that translates to LR.

Quote from the above linked article by Jeffrey Friedl:

For a print that big, & for a client who will do who knows what with the file, I'd only use 100%.