Dpi question

Discussion in 'Photography Beginners' Forum' started by HarryWho, Aug 4, 2006.

  1. HarryWho

    HarryWho TPF Noob!

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    Hi, I'm new here so hello to everyone. Can you tell me why cameras output images at 72dpi instead of 300dpi which all printing labs require? It seems that when I convert to 300dpi the image is pixilated due to the massive increase in size. Are there cameras that will provide 300dpi images?
     
  2. Tiberius

    Tiberius TPF Noob!

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    The camera's dpi setting means nothing. Ignore it. Printing labs just read the pixels. You send them a file, request a certain print size, and the camera's dpi setting is completely discarded.
     
  3. HarryWho

    HarryWho TPF Noob!

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    Thanks for that. But why do they ask for 300dpi?
     
  4. Tiberius

    Tiberius TPF Noob!

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    Because in terms of Digital Printing, that's typically regarded as "Photo Quality". If you have three hundred pixels for every inch of printing size, the print will be indistinguishable from a photo. Of course, that number's got a rather safe buffer in it; 150dpi still looks fantastic and I've gotten away with less although I wouldn't necessarily reccomend it.
     
  5. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    DPI and resolution are not the same thing. Resolution is how many pixels the image is made up of; it's the size. DPI is how many of those pixels are you going to print per inch; it's the scale. If you print a 1000x1000 image at 100 dpi it's 10"x10". If you print it at 200 dpi it's 5"x5". But either way it's still 1000x1000 resolution. If resolution is a piece of paper of a particular size, dpi is sort of whether you are going to measure it in mm, cm, inches, feet, etc...

    When you change your DPI from 72 to 300 make sure you are not changing the resolution. It's sounds like you are changing DPI, and changing the resolution, which is easy to do since in most graphics software they are usually controlled in the same window. There should be a way for you to change DPI, without changing resolution.

    Unless you are doing the printing, you really don't need to worry about it. When a lab asks for 300 dpi what they are saying is that's what they want for max print quality. Take your resolution, and divide it by 300 (per dimension), and that's the biggest size print you can get at max printing quality. So to get a perfect 8"x12", your file should be at least 2400x3600 resolution. If you ask for a 4"x6" print from that same file your DPI would be 600 (technically, but their machines still only print at a max of 300 dpi). If you ask for a 12"x18" then you are dropping DPI to 200. Depending on the subject matter and personal opinion this still may make a decent print.

    Unless you are printing your own you probably really don't need to worry about it. If it's causing problems at your lab, find a new lab.
     

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