On Thu, Nov 22, 2007 at 02:38:14PM +1100, Steve Bennett wrote:
On 11/22/07, Stephen Bain stephen.bain@gmail.com wrote:
There's a discussion about it currently on commons-l, prompted by an inquiry from a magazine publisher about possibly using some Commons images, but unsure about their print-suitability.
For these kinds of reusers, it would be useful to allow some kind of RAW format, and DNG is probably the best one to pick, given that it's (relatively) open.
Interesting - even our highest quality 10mp JPEGs aren't good enough? I'm curious, because at [[WP:FPC]] we've generally considered that featured pictures should be big (heh, minimum 1000px) to allow them to be printed. It sounds like that's really nowhere near enough.
I actually have an answer on this for you. :-)
For print reproduction, you typically want at least 2x the linescreen of the halftone reproduction, and maybe a little more.
For magazines, that's 120-175ls, and for books, maybe 133-200ls, depending on the market and the publication technology (bothering with screens higher than 133-150 requires that you get everything else in the publishing chain exactly right.
So, multiply those by 2 or 3, and then divide to get inches.
And remember that if your JPEGs reflect sensor oddities or sloppy compression, then you're going to scale those up as well.
So, 1000px? 4 to 5 inches, tops. If you need to fill a page, plan on needing an entire uncropped 10-12mp JPEG, and remember that fashion spreads are being shot on 22mp Hasselblads. Got $38K? :-)
Cheers, -- jra