DPI only 72 on 7.1 megapixel image?

Discussion in 'Photography Beginners' Forum' started by mikec, Sep 15, 2007.

  1. mikec

    mikec TPF Noob!

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    I just got this email from my graphic designer:

    "It looked a little fuzzy to me when I opened it up and I checked the dpi and it is only 72 dpi, so we really can't use it for print work, I need at least 150 dpi for print and I really prefer 300 dpi especially if it is going to be retouched or needing to be cropped out of the background."

    I had used the Olympus SP550UZ and set it to the highest resolution, SHQ (super high quality) I guess it stands for. I thought if you set the digital camera to the highest resolution, in this case, 7MP that it enables you to print out photos? From the features page of this camera:

    "Shoot and print in rich detail with the 7.1-megapixel imager."

    What am I missing here? What's the point of all these megapixels if they are only for screen resolution?
     
  2. Patrolman Pat

    Patrolman Pat TPF Noob!

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    I'm not familiar with that camera but I would have thought it was a software issue rather than a camera setting issue. What editing /compression software are you using??
     
  3. mikec

    mikec TPF Noob!

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    All I did was open the photo up in photoshop and went to the image size dialog and that's where it says 72DPI. Can I just change the DPI from 72 to 300 without changing the print size? Seems like I read that somewhere?
     
  4. Digital Matt

    Digital Matt alter ego: Analog Matt

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    First things first, DPI is meaningless on a monitor. It only factors in when you print, and it is a setting that you determine.

    Print size = pixel dimensions / DPI.

    8" x 10" image = 2400 x 3000

    2400 / 300 = 8
    3000 / 300 = 10

    To change the PPI (pixels per inch) in photoshop, go to image size, UNcheck resample, and set the PPI to 300. Then recheck resample. The pixel resolution has not changed, but the output print size will now reflect that of a 300 DPI print.
     
  5. mikec

    mikec TPF Noob!

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    OK, that is what I thought (sort of) So the picture I shot at 3072x2304 will translate to a 10.24"x7.68" print, at 300 DPI, correct? When I re-check the resample image box, what should I pick in the drop down (it says bicubic) before hitting OK?
     
  6. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Bicubic resampling is what you want, but that is only if you intend to enlarge the photo, or scale it down. I don't know what version of photoshop you are using, but CS and CS2 offer two different kinds of bicubic resampling. Sharper, and softer. Sharper for downsampling, softer for upsampling.

    Btw, if your graphic designer doesn't understand resolution, I'm scared for his career.
     
  7. mikec

    mikec TPF Noob!

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    Thank you for your help. I knew I had read something somewhere about DPI and resolution confusion..
     
  8. cecilc

    cecilc TPF Noob!

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    Yea, I was thinking the same thing ....

    I mean, that's just basic stuff for graphic designers ... and if he doesn't know those basics, I'm not only scared for his career, I'd be scared of how your images look after he gets through with them ....
     
  9. SYKES3

    SYKES3 TPF Noob!

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    Well, I think this is just the question I am grappling with right now. Since this is a beginner area, I feel safe to show my ignorance.

    I need to photograph my watercolor paintings to make giclee prints. Not photo prints. In my research I read that the camera determines how many DPI will be printed. I hear that my Nikon COOLPIX 5 megapixel is not adequate for this. I need between 150 and 300 DPI. The Coolpix does not capture enough information. Also was told that trying to enlarge the file in photoshop would not work for these prints. You can not make better than you capture.

    I am about to buy a Canon Digital Rebel XT SLR 8 Megapixels. I am going to make the same size print as I capture. My paintings are mostly 15 X 22". The prints will be the same.

    Am I confusing DPI and resolution? Any help would be appreciated. SYKES3
     
  10. Digital Matt

    Digital Matt alter ego: Analog Matt

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    If you read my replies above, you'll see that your question was already answered.

    There are 2 different factors of resolution. The resolution of the digital file, which is the pixel resolution, ie 2000x3000 pixels. Then there is the resolution that this file is printed at, which is the DPI. (Dots per Inch) How densely you print those 2000x3000 pixels will determine how large the print is.

    Print size = pixel dimensions / DPI.

    8" x 10" image = 2400 x 3000

    2400 / 300 = 8
    3000 / 300 = 10

    To change the PPI (pixels per inch) in photoshop, go to image size, UNcheck resample, and set the PPI to 300. Then recheck resample. The pixel resolution has not changed, but the output print size will now reflect that of a 300 DPI print.
     
  11. SYKES3

    SYKES3 TPF Noob!

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    This post explained it much better. Don't be impatient with me, this is the beginners area, and with digital, I am a beginner. Thanks for spelling it out better for me.

    I also need help with lighting for photographing paintings indoors. Sometimes through glass, if that is possible. Where should I ask about this? SYKES3
     
  12. Digital Matt

    Digital Matt alter ego: Analog Matt

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    SYKES3, anytime you have questions like this, you should start your own thread so you don't hijack this one. The beginner's area is a good place to ask questions like this.
     

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