December 7, 2008

Home Photo Friday – The Scoop on Photo Resolution

by Irene Nash

Libby at the studio getting her picture taken

Libby and I got our photos taken earlier this year by Jamie Pflughoeft, owner of the wonderful Cowbelly Pet Photography, and I emailed her last week to ask why the photos that were supposed to be high resolution were 72 dpi (dots per inch) instead of 300 dpi, which is what’s normally used for print.

She emailed back such a nice explanation I thought I’d include it here, since a lot of people (including me, obviously) get confused about this.  Here’s Jamie’s answer:

Resolution has nothing to do with dpi.

1. All digital files come out of every camera at 72dpi. This refers to dots per inch, sometimes also known as ppi, or pixels per square inch. This has nothing to do with resolution, only printing. More on that in a minute.

2. RESOLUTION refers to the actual size of the file in dimensions. The images that come from my full frame Canon 5D have a resolution of 2912×4368. The only camera that produces higher resolution files is the Canon Mark II, but that’s totally overkill for this type of use.

3. Back to dpi, this number depends on what type of printing you want to do.

  • ALL web and email use is always 72 dpi.
  • Straight photo prints are between 200-300 dpi, depending on the lab.
  • Promo product printing like brochures and biz cards is usually 300 dpi, but again, this depends on the lab. Every printer has their own suggested file requirements.
  • Magazine printing can be up to 600 dpi, again, depends on the magazine.

Billboard printing pretty much demands the use of film, because the photos are so huge.

4. Sizing an image for print.

You can either crop to the dpi and size that you want- say 8 x10 inches at 300 dpi, or you can use ‘edit- image size’ – and type in the dimensions and dpi you want there. You can do this without needing to upsample, although Photoshop is very good at upsampling. Unless you are doing a gigantic print, you won’t need to upsample a file that is as high resolution as 2912  x4368.”

The bottom line:  Your web photos of listings will load quickly and still look good at 72 dpi, while your flyer photos will turn out better at 300 dpi, or even 150.

(For small print flyer photos 72 dpi still seems to work out fine as long as the digital dimensions of the photo are not smaller than the dimensions in print, but it’s safer to go with higher dpi.)

Hope this helps.  I highly recommend checking out Jamie’s site, starting with the beautiful pictures of Libby on the Cowbelly blog.  (Just ignore the other dog.  Kidding, kidding. :))

If you’re in Seattle and want a great photo of your pet I highly recommend Jamie.  (And she will ply your dog with organic buffalo and green-lipped mussel dog treats – I kid you not.)  You, on the other hand, might starve if the shoot goes long, so bring a muffin.

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