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Thread: How to measure Cropping

  1. #1
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    Default How to measure Cropping

    When someone asks the question - Was it a big crop? What does that mean? How can you measure your cropping?

    I borrowed this example from Rich Ditch's blog.

    Original -- 3000 x 2000 = 6MP
    Cropped -- 2500 x 1500 = 3.75MP
    3.75 / 6 = .625 or 62.5% crop

    Using the above algorithm, what is a large crop? Anything over 50%? Anything over 60% or ??

    Is there a better way to compute cropping?

  2. #2
    Robert Amoruso
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    Scott,

    For me a large crop is where I start to see degradation in the image such as loss of detail. All depends upon how large the file is resolution wise and how well I exposed the original, was it critically sharp, etc.

    But if I were to put a number on it I feel 25% of the original image size is a large crop.

  3. #3
    Alfred Forns
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    Hi Scott It is a difficult one to answer but as Robert pointed out having 25 of original is a large crop. With the high MP cameras things are changing but I like having at least 70% of the image to be happy !!

  4. #4
    William Malacarne
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    or is the OP talking of what is often called a 100 crop...such as
    http://www.pbase.com/wlhuber/100_crop_

    Bill
    not the same Bill that did the web page

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    Scott, welcome to BPN! Tell Rich hi for me. Long time no see. He is a terrific photographer. Your coming along nicely too. I agree with Robert's answer. I usually do not go below 50% of the original image. And thats pushing it to me.

  6. #6
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    I struggle with this as well. To me an image that represents less than 50% of the original usually doesn't have enough detail to be high quality. Of course the newer cameras with high MP can be cropped more, and may be the equivalent of a good image from a camera with less MP. However, you are still throwing away detail that would be great to see.

  7. #7
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    Of course with the high megapixel cameras, you can crop a lot. For example, with the 5D Mark II you can crop to 30% of your original pixel count and you go from 21 megapixel to 8 megapixels giving the same area and megapixel count of a 30D. So it's all relative. I'm changing to specifying crop to how many megapixels are left. For example, this leopard image is cropped to 14 megapixels (from 21):
    http://www.clarkvision.com/galleries...791.c-800.html

  8. #8
    Alfred Forns
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    I was wondering how some contest might view copping? A 75% crop from a 1DsMk3 will still has lots of pixels but I wouldn't consider it as a quality image. Interesting subject !!

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