It is 1.41. Thats the exact correct figure.
Of course you can use whatever you like but it is bad advice to go any lower.
If for yourself you can do what you like. But to offer advice to someone else to go below the recommended and correct mathematical resolution is really bad.
We have to be careful. We dont even know the LPI or if its being printed digitally or not.
As this is someone elses request for info we have to give accurate and not guesses in the advice
The situation is that I´ll pass the jpeg file over to it’s owners. At the same time I must confess that I´v done a bad mistake by loosing the backup and raw files. After external hdd suddenly died (reading head) all is left is this file, originally made for FB use. I want to be able to explain what it means in practice when the photo is printed in newspapers and magazines. Based on what I´v learned from You, everything seems to be better as I first thought. So once again, thank You for big help!
If it’s just a failed head with little or no damage to the disc, it can likely be fixed or have the data recovered. You probably know that, though.
What is FB use?
FB to me means flatbed printing and that resolution is all dependent on viewing distance somewhere in teh 75-150ppi range.
Billboards are generally 30ppi full scale. Not single digits. I don’t print anything under 25ppi. Or at least not on purpose.
Even for a good quality lambda print, for say, an educational museum exhibit, 200ppi is more than adequate. 150ppi if using any of the digital inkjets. Art prints you want to go high 400-600.
No idea what the OP is printing here (and I mighta missed where they may have said.) We’re all assuming it is litho/offset/digital offset. That might be wrong
Unfortunately some damage on disc. I took it to data recovery service. They change the head in next days and after some time we’ll know is there anything to recover. I had backup but by a stupid mistake lost it. I´ll have a tattoo on my hand with “backup now” text…
FB meaning Facebook in my post. I´v learned that 2048px wide would be good for a Facebook use. Printing of this file will be done someone in a newspaper or in a magazine. But as I wrote, I´v learned a lot from You. Thanks again!
Just to clarify, I was referring to lpi not ppi when I mentioned single digits. There are, of course, no halftone dots with large-format digital printing, so lpi doesn’t translate very well but out of habit, I still think in those terms. Even then, as you mentioned, print quality in large format hardly ever gets that low. I was marginally involved with some of the huge banners that hung from some of the tallest buildings here in SLC during the winter olympics (below) that were easily the equivalent of single digits, but that was really an exception.
Way back in college (before digital printing — late '70s), I had a summer job at a screen printing shop. We mostly worked on museum displays and exhibits of various kinds, but there was also the occasional semi-permanent, housing subdivision billboard job that would come through.
Screen printing being what it is, we needed to use actual halftone dots to simulate a single-color continuous tone image. I don’t remember the exact lpi of the halftone, but I remember the dots seeming nearly as big around as the end of my little finger, so maybe 4–5 lpi. They looked a little rough from the highway, but for the time, acceptable, I guess.
Those big building banners sometimes run more “inches per dot” than dot per inch, LOL. I’ve avoided those things like the plague. So far, knock on wood, so good.
edit:
(I just realized that old saying has new meaning in the age of Covid. Maybe I need to step up my game a bit and more like avoid things as if they were a T-rex or something…LOL.)
