Confused about Resolution!!!

Discussion in 'Photography Beginners' Forum' started by sawyer1206, Sep 1, 2008.

  1. sawyer1206

    sawyer1206 TPF Noob!

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    I am confused about Photo Resolution. My XTi produces images with a resolution of 3888 x 2592. The image has a resolution of 72 ppi and I have read on this site that you should have atleast a 300ppi to print the image. I shoot with the highest jpeg setting on my XTi and I'm getting the 72 ppi is this right?
     
  2. ksmattfish

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

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    Ppi is scale, not resolution. If you have an image file with a resolution of 1000x1000 then it would be 10"x10" at 100 ppi or 4"x4" at 250 ppi. You probably only have to worry about ppi if you are printing your own.
     
  3. tirediron

    tirediron Watch the Birdy! Staff Member Supporting Member

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    You're confusing PPI (Pixels per inch) and DPI (Dots per inch) - not your fault, the two terms are used interchanably and often incorrectly by many people. Monitors think in PPI (and 72 PPI is the standard web resolution for .jpg images), printers think in DPI, that is, how many dots of ink are put on the paper per inch. They can be thought of as equal but different, this is why when you take your .jpg image and zoom to 100% using the Windows viewer (or other application) it's huge, but when it's printed, it's much smaller.

    Assuming 300 DPI, the maximum image size your camera can produce is 12.96 x 8,64 inches (In reality with modern photo printers you can go as low as 240 DPI). When you use Photoshop, PaintShopPro, or whichever application, you either set in the preferences or when you crop, what you would like the print resolution to be.
     
  4. ksmattfish

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

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    Ask your lab what they recommend. Many of the newer printing machines that do C prints (typical color photos) max out at 250 ppi. Recently I made some 20"x30" prints from 20D files. The original files were approx 3500 x 2300. I used Photoshop bicubic smoother to upsize them to 7500 x 5000, and they look great. Even when viewed like a photo geek (6" away) they are sharp and show no pixelization.
     
  5. sawyer1206

    sawyer1206 TPF Noob!

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    Ok, I think I understand now. When I open an image in Adobe CS3 and open up the image size window the top section gives me the actual pixel dimensions and the bottom section gives me the actual pictue size. So if I understand correctly then the resolution box at the bottom of the window is what my monitor is going to display and has nothing to do with picture size. Is this correct?
     
  6. prodigy2k7

    prodigy2k7 No longer a newbie, moving up!

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    I think its dumb, ya DPI used for printing, but a DOT (per inch) is a pixel. Should be the same as Points Per Inch..
    Don't think about definition think about what its saying.
    Dots per inch
    Pixels per inch
    shouldn't they mean the same thing even though they dont?
    Dont worry about DPI until you print or crop
     

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