dpi of images in image library

[topr8]

i'm beginning to think ahead and am thinking of starting a small, niche image library.

anyone who uses such libraries know what kind of quality images would be required?

i'm wondering if 300dpi tiff's would be good enough or do i need more?

these grafics would probably be used both in print/magazine industry and possibly online - obviously for the web i'm ok, but i need guidance more for what a potential print customer would want.

[solidgas]

If you are catering towards the print market then you will most definitely want 300 dpi images for download. Of course you will want to downsize those large images for preview purposes down to 72 dpi.

[monkeythumpa]

9x11 inches at 300 dpi should be sufficient for magazines.

[topr8]

thanks, thats just what i needed to know

[Don_Hoagie]

Well, although no one here is outright wrong, their replies appear to be a bit vague, and possibly misleading. With that in mind, this is my reply:

If you provide images online at 300dpi, the actual size of them when printed will be much smaller than your "standard" 72dpi web image. Much better-looking, but much smaller nonetheless.

If you are concerned about that, as you should be, then your two feasible options would be:

1) Provide the image online at huge pixel dimensions... this would be good for print, but not so good for web.
2) Provide a "web preview" at 72dpi, and then have a link to the hi-res file.

Of course, if you're not concerned with the changing of the image size, then you can do whatever you like... in fact, leave it at 72dpi if you feel like it. Any designer worth his salt who would use your images is going to apply the file to an already established layout, which will undoubtedly be of a different dpi resolution. Your image will be assimilated to that layout's resolution at that point, regardless of your own settings.

Edit: You also asked what would suffice for print genres...

-150dpi is the standard newspaper print resolution
-300dpi for "low to mid-level" mags... obviously some mags are all about quality imagery, and they tweak their images higher than that
-600dpi will cover you for most things printed. This would include a good magazine, an image on a postcard, a poster, etc. Images at 600dpi are pretty much "real life" to the average joe. Of course, having a 9x11 inch 600dpi file online would mean the pixel dimensions would have to be... i dunno... 6000x7000 pixels?