Identify what size a photo is from pixels

Discussion in 'Photography Forums' started by RajP, Sep 6, 2012.

  1. RajP

    RajP
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    Quick question for you all.. how can I translate a photo that is shown in LR4 as 4156 x 2699.. what does this translate into Centimetre or Inch?? I tried using the following site Pixels (X) to Centimeters Conversion Calculator and it tells me 1 cm is 37.795275591

    which turns out to be 109 x 71 cms approx... am I right?
     
  2. Dancook

    Dancook
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    It depends on what PPI you're going to use.

    http://www.nps.gov/museum/publications/conserveogram/22-03.pdf

    If you're going to have something printed, I believe it's best to speak to the printer. Because printers printers :) have different capabilities. They will be able to give you an idea of the biggest print you can get away with.
     
    Last edited: Sep 6, 2012
  3. RajP

    RajP
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    Cheers Dan... what I was trying to work out is if I wanted to print that image to a 7x5 format in Tesco, will I need to resize the canvas to do that? I would assume so...
     
  4. Dancook

    Dancook
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    Then it won't matter on the actual resolution (as long as it's high) just crop it so that the ratio is 7:5. It will downscale it to fit anyway (assuming it's the same as jessops! hah).

    So for example 3500 x 2500 pixels - since you've already provided dimensions of 4156 x 2699,the largest 7:5 size you could use is 3778.6 x 2699. Calculated by (2699 / 5 * 7)

    If you don't crop it to your taste, I suspect Tesco will auto crop part of it.
     
    Last edited: Sep 6, 2012
  5. RajP

    RajP
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    thanks for that... so the logic is to take the smaller of the 2 sizes and then divide by the desired size of the pic should give you the second dimension for the pic!!!:smashin:
     
  6. Dancook

    Dancook
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    You've probably got it, but to summarise. To maintain a 7 x 5 ratio

    Short side length / Short side ratio * Long side ratio = Long side Length



    You could do it with the long side, but you'll see the flaw.

    4156 / 7 x 5 = 2968.57

    So 4156 * 2968.57, is also a 7 x 5 ratio - However you can't normally make your short side longer.
     
  7. RajP

    RajP
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    :thumbsup::thumbsup::thumbsup:
     
  8. Faldrax

    Faldrax
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    As a rough guide to image sizes, on screen things are typically displayed at 72 ppi - IE 72 pixels = 1", while printed images are anything from 150-300 ppi (higher ppi typically means better quality), in part depending on how close you will view the image - less ppi required the further away you are viewing from.
     
  9. mucca_D

    mucca_D
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    In LR just select the crop tool in the develop mode and from the drop down select the crop you require. or if not in the list use custom and select the ratio. Then export and job is a good un.

    HTH

    D
     
  10. RajP

    RajP
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    Thanks for that. I did dig thru LR and found that setting too!! Works a charm too!!!
     

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