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Sensor Photo Detectors vs Effective Pixels

Discussion in 'Digital Photography & Imaging' started by Alex Ethridge, Sep 24, 2003.

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  1. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

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    What is the difference between Sensor Photo Detectors and Effective Pixels? I guess my question goes more to what the point is in having these two different numbers and how they are intertwined with each other.

    Example: The Olympus E20 has 4.92 million Effective Pixels and 5.24 million Sensor Photo Detectors.
     
  2. kiwiguy

    kiwiguy

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    The CCD (Charge Coupled Device) that produces the image has a grand total of 5.24 million pixels. The useable area accounts for 4.95 million pixels.

    Its logical that they cannot use every pixel right out to the edge, there has to be a defined image area edge without running out of pixels. Also the "grouping" of pixels will leave some unuseable incomplete clusters at the extreme edges of the CCD chip
     
  3. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

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    Thanks for the reply.

    It no longer surprises me when I find things like this. Hard disk manufacturers call a Megabyte 1,000,000 bytes and now Camera manufacturers are counting pixels that don't work.
     
  4. kiwiguy

    kiwiguy

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    One of my digicams has 3.1 million pixels, but claims 6 million "effective" pixels! (Fuji F602Z)

    Because the pixels overlap due to their hexagonal shape, they do a hardware interpolation to get extra data based on the average of the pixels each side. I knew all the details before I bought, so it wasn't a surprise, and it works just fine.
    I would not claim to get 6 megapixel resolution but the quality is very good.

    Its just like buying a computer monitor. A 17" CRT is a tad over 15" viewable. They mask off the edges. At least with LCD screens you do get what you pay for
     
  5. wanabe_buck

    wanabe_buck Guest

    Howdy

    As Kiwiguy said...

    here's a link you may have seen...

    Effective pixels

    mostly a marketing thing I guess...more pixels = better quality

    buck
     
  6. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

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    Well, it looks like there is more to it than just the masked pixels.

    Good link.
     
  7. hewee

    hewee

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    I would just go by the Effective pixels as to how good it is.
     
  8. Alex Ethridge

    Alex Ethridge It's My Birthday! Thread Starter

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    How good it is, isn't what I am after. I want an education in this and wanabe's link to Megapixel.net is a good one. I don't know why I didn't think of it myself.

    I guess when I want to know anything I come here first.
     
  9. hewee

    hewee

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    Yes this is the place to come to for help. :)
     
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