"pixel size" (not pixel dimensions)

Discussion in 'Photography' started by Ivory, Feb 6, 2008.

  1. Ivory

    Ivory Guest

    What does "pixel size" (not pixel dimensions) mean? (I realize that
    changing the resolution changes the size of the image, what UCLA calls
    the document size.)

    Does anyone know for sure how one changes "pixel size" (in Photoshop,
    etc.)?
     
    Ivory, Feb 6, 2008
    #1
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  2. Ivory

    ray Guest

    I'm certainly no expert in the technicalities, but it would seem to me
    that "pixel size" only makes sense when talking about physical media -
    i.e. if you know the size of a camera sensor or a computer monitor and
    you know it's dimensions in pixels, then you can easily calculate the
    size of a pixel.
     
    ray, Feb 6, 2008
    #2
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  3. Ivory

    Marvin Guest

    A pixel doesn't have an inherent size. If you display an
    image at 100 ppi, each pixel is 1/100" wide. But "pixel
    size" is often used to mean the number of pixel in the
    image. It is a "size" of the image.
     
    Marvin, Feb 6, 2008
    #3
  4. Ivory

    Ivory Guest

    I guess what you're referring to is "pixel dimensions," the size of
    the image in screen pixels, i.e., 1680 x 1080, or 800 x 600, etc.
     
    Ivory, Feb 6, 2008
    #4
  5. Ivory

    Joel Guest

    I have no idea what you mean by "Pixel Size" vs "Pixel Dimentions" and I
    have never heard of anyone comparing the two above to give me the idea what
    they are.

    But I can give you a general information about the whole thing.

    - The Image Value is based on W(idth) x H(eight) x R(esolution)

    1680x1080 and 800x600 is a FULL value of Monitor Resolution *but* an
    incomplete value of the Digital Image Resolution which requires 3 separated
    values.

    Or in Digital Image the "1680x1080" doesn't mean anything. But

    1680x1080 x 300-ppi = some value
    1680x1080 x 2-ppi = some value (less then the above but has some value).

    PHOTOSHOP - if you use the "Image Resize" option then Photoshop will give
    you 2 options to deal with the resolution "Re-Sample" vs "Not Re-Sample"

    Example you have total of 10,000 pixels (or 10,000 dollars)

    *NOT* Re-Sample = you will have 10,000 pixel no matter how you change thing
    around. Or the VALUE will remanin the same as original VALUE

    Re-Sample = you give Photoshop the option to change thing to whatever you
    tell it to do, and you will end up with either. SAME or less than the
    original VALUE.

    - Or if you have 100 dollars, you can have either (10) $10, (5) $20, (100)
    $1 and so on. But the value won't be more than $100 (or not to
    Re-Sample)

    - Now if you throw away $20 then you will end up with $80 instead of $100
     
    Joel, Feb 6, 2008
    #5
  6. Ivory

    Cats Guest

    To me they are the same. Resolution (as in dpi/ppi) only means
    something when an image is printed. You can change the dpi/ppi in
    Photoshop or PaintShopPro in one of two ways - the resolution is
    changed and that's it, or the image can be resized so that it
    maintains the same dimensions from whatever ppi it had before to
    whatever ppi it had afterwards. There is a checkbox in PaintShopPro
    (and I think in Photoshop) that controls the behaviour.

    Be very wary about doing this when more pixels are required, as it can
    lead to lose of quality.
     
    Cats, Feb 6, 2008
    #6
  7. Ivory

    T Shadow Guest

    http://en.wikipedia.org/wiki/Pixel
     
    T Shadow, Feb 6, 2008
    #7
  8. Ivory

    SteveB Guest

    Oh, good grief. Not another "size" thing, I hope.

    Steve ;-)
     
    SteveB, Feb 7, 2008
    #8
  9. Ivory

    Paul Furman Guest

    The only sense I can make of 'pixel size' is the physical size of pixels
    in digital cameras. If it's something you change and not the number of
    pixels then it's print size (dpi, ppi, etc).
     
    Paul Furman, Feb 7, 2008
    #9
  10. Ivory

    Rob Morley Guest

    >, Ivory
    says...
    Context?
     
    Rob Morley, Feb 7, 2008
    #10
  11. Ivory

    SteveB Guest

    Do the math.
     
    SteveB, Feb 7, 2008
    #11
  12. Ivory

    Rob Morley Guest

    Does that answer my question?
     
    Rob Morley, Feb 7, 2008
    #12
  13. Ivory

    Peter Guest

    To me they are the same. Resolution (as in dpi/ppi) only means
    something when an image is printed. You can change the dpi/ppi in
    Photoshop or PaintShopPro in one of two ways - the resolution is
    changed and that's it, or the image can be resized so that it
    maintains the same dimensions from whatever ppi it had before to
    whatever ppi it had afterwards. There is a checkbox in PaintShopPro
    (and I think in Photoshop) that controls the behaviour.

    Be very wary about doing this when more pixels are required, as it can
    lead to lose of quality.

    Yes they can, but the algorithms in CS3 and Genuine Fractals do a pretty
    good job of allowing us to make huge prints from small images. What we
    sometimes forget is that enlargement will also bring out the defects.
     
    Peter, Feb 8, 2008
    #13
  14. Ivory

    SteveB Guest

    Did you post a question? I don't see it.

    Steve
     
    SteveB, Feb 8, 2008
    #14
  15. Ivory

    Rob Morley Guest

    I asked:
    Context?

    And you replied as quoted above.
     
    Rob Morley, Feb 8, 2008
    #15
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