Information needed

Discussion in 'Digital Cameras' started by Noname, Jul 13, 2004.

  1. Noname

    Noname Guest

    Does any know of a web site that explains bytes, pixels and image size?. Or
    is there an easy formula to calculate this?. Along with this information ,
    how do I calculate what size picture I would be able to get out of this.

    EX: 230000 bytes = how many pixels and what size file.
    What size picture ( 3x5 )
     
    Noname, Jul 13, 2004
    #1
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  2. Noname

    Michael Ryan Guest

    Michael Ryan, Jul 13, 2004
    #2
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  3. Good luck on your quest Noname

    (I think I will sit this one out :)

    Artie
     
    Arte Phacting, Jul 13, 2004
    #3
  4. ....

    As has been explained many times, you are asking for something that doesn't
    exist.

    The number of pixels is simply the number of "colored dots" in the array of
    dots produced by the digital camera. This number can be increased or decreased
    by software, but the maximum useful number is the number of light sensors positions
    across the face of the chip in the digital camera. If the camera has an array of 3
    million light sensors (and those sensors can be any of a variety of types, so don't
    get bogged down with whether the sensors have one or more parts), then it produces
    an array of 3 million "colored dots". Any less is throwing something away. Any
    more adds nothing.

    A byte is simple a unit of computer memory. The number of bytes per pixel is
    depends on the representation of the information in the pixel. The raw output of
    the camera, today, is somewhere from 8 bits (1 byte) per pixel to 48 bits (6 bytes)
    per pixel. The number of bytes in the image is a totally different matter, however.
    The image file format could be such that the number of bytes equals the number
    of pixels multiplied by the number of bytes per pixel (such as in a TIFF file). Or
    it could be considerably less (due to both lossless or lossy compression as in
    a JPEG file).

    The "image size" is always the number of pixels. It is also the size of the printed
    picture. There is absolutely no relationship between the number of pixels and the
    printed size. That's totally up to you. You can take your 3 million "colored dots"
    and spread them across a bill-board sign (where they'll look pretty poor up close),
    or you can spread them across a postage stamp (where the printer probably threw
    a bunch of your dots away since it couldn't fit them all). "Pixels per inch" is often
    a useful guide to how good a print will look. "Pixels per inch" is exactly what it
    sounds like: number of pixels divided by number of inches. 800 pixels spread across
    8 inches is 100 pixels per inch. 800 pixels spread across 2 inches is 400 pixels per
    inch. One will look much better under a magnifying glass. One will be more visible
    hung on a wall. Some (really loose) rules of thumb: 300 pixels per inch will look
    great to nearly everybody. 600 pixels per inch is probably more than any common
    printer can use. 150 pixels per inch is probably fine for snapshots for your Grandmother.

    Four color inkjet printers probably can't produce more than 150 to 200 pixels per inch.
    (Remember, they have to create all the colors in the image from multiple dots of their
    5 colors - 3 "colors", 1 black, white paper.) A good 6/7/8 color inkjet probably can
    probably do somewhere between 200 to 300 pixels per inch. A dye sublimation
    (or other 24 bit color) printer can produce 300 or more pixels per inch.

    Now, that wasn't so bad, was it? }:)


    --
    Dan (Woj...) dmaster at lucent dot com
    ----------------------------------
    "What can you see / On the horizon?
    Why do the white gulls call?
    Across the sea / A pale moon rises.
    The ships have come / To carry you home.
    And all will turn to silver glass.
    A light on the water / All souls pass."
     
    Dan Wojciechowski, Jul 15, 2004
    #4
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