size of a raw images - comparison?

Discussion in 'Digital Photography' started by John, Jun 16, 2008.

  1. John

    John Guest

    Hi,
    Can any one tell me how the size of raw image computed?

    say VGA - 640x480?

    How may bytes will be one full frame?

    how much will be the size of each pixel?

    How many pixels constitutes one full line in the frame?

    How different is it for foveon cameras?

    How much bytes will each line of the frame contain and what will be
    the
    pixel size in foveon cameras and ordinary cameras

    Regards,
    Jm
    John, Jun 16, 2008
    #1
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  2. John wrote:
    > Hi,
    > Can any one tell me how the size of raw image computed?
    >
    > say VGA - 640x480?
    >
    > How may bytes will be one full frame?


    Typically:
    12 bits x 640 x 480

    > how much will be the size of each pixel?


    12 bits, as it contains only one colour

    > How many pixels constitutes one full line in the frame?

    640, but they will be 320 R + 320 G, or 320 B + 320 G pixels

    > How different is it for foveon cameras?
    >
    > How much bytes will each line of the frame contain and what will be
    > the
    > pixel size in foveon cameras and ordinary cameras
    >
    > Regards,
    > Jm


    I hope that helps somewhat. I don't know how many bits Foveon uses, but
    it records an RGB value at each pixel - but it does not have as many
    pixels as a Bayer camera.

    Cheers,
    David
    David J Taylor, Jun 16, 2008
    #2
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  3. John

    ben brugman Guest


    >
    > Typically:
    > 12 bits x 640 x 480
    >

    Not all Raw is 12 bits.
    Typically Raw is compressed.

    Example for Nikon
    Size of the raw is 3037 x 2012.
    One day,
    Smallest 4785KB
    Largest 7106KB
    Average 5408KB

    Average is pretty stable. (Works out to 0.9 byte for each pixel).

    Ben
    ben brugman, Jun 16, 2008
    #3
  4. ben brugman wrote:
    >> Typically:
    >> 12 bits x 640 x 480
    >>

    > Not all Raw is 12 bits.
    > Typically Raw is compressed.
    >
    > Example for Nikon
    > Size of the raw is 3037 x 2012.
    > One day,
    > Smallest 4785KB
    > Largest 7106KB
    > Average 5408KB
    >
    > Average is pretty stable. (Works out to 0.9 byte for each pixel).
    >
    > Ben


    Thanks, Ben. I was trying to give a first-cut answer to demonstrate the
    principles, so it's helpful to have your input as well. I know that Nikon
    offers both lossless and lossy compression as well. What sort are you
    using for the figures above?

    Cheers,
    David
    David J Taylor, Jun 17, 2008
    #4
  5. John

    nospam Guest

    In article <61s5k.10332$>, David J
    Taylor <-this-bit.nor-this-bit.co.uk>
    wrote:

    > > How different is it for foveon cameras?
    > >
    > > How much bytes will each line of the frame contain and what will be
    > > the
    > > pixel size in foveon cameras and ordinary cameras
    > >

    > I hope that helps somewhat. I don't know how many bits Foveon uses, but
    > it records an RGB value at each pixel - but it does not have as many
    > pixels as a Bayer camera.


    sigma uses a12 bit a/d converter, then it goes through a funky lookup
    table that scales the data and applies some sort of colour conversion,
    and then it's lossy compressed (sigma calls it 'nearly lossless').

    it's not exactly 'raw.'
    nospam, Jun 17, 2008
    #5
  6. nospam wrote:
    []
    > sigma uses a12 bit a/d converter, then it goes through a funky lookup
    > table that scales the data and applies some sort of colour conversion,
    > and then it's lossy compressed (sigma calls it 'nearly lossless').
    >
    > it's not exactly 'raw.'


    Half-baked?

    David
    David J Taylor, Jun 17, 2008
    #6
  7. John

    nospam Guest

    In article <NaJ5k.10737$>, David J
    Taylor <-this-bit.nor-this-bit.co.uk>
    wrote:

    > > it's not exactly 'raw.'

    >
    > Half-baked?


    the file format isn't the only thing about the sigma cameras can be
    considered 'half-baked.' :)
    nospam, Jun 17, 2008
    #7
  8. John

    Chris H Guest

    In message
    <>,
    John <> writes
    >Hi,
    > Can any one tell me how the size of raw image computed?
    >
    > say VGA - 640x480?


    Cameras that give RAW format(s) are generally a lot higher than VGA

    > How may bytes will be one full frame?

    Difficult there are several frame sizes used on "35mm" DSLRs and it
    depends on the MP of the camera

    http://en.wikipedia.org/wiki/RAW_image_format

    http://www.tidalwave.it/infoglueDeliverLive/ViewPage.action?siteNodeId=18
    6&languageId=1&contentId=-1#1.1

    --
    \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
    \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
    \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
    Chris H, Jun 17, 2008
    #8
  9. John

    John Guest

    Why 12 bits? isnt it 36 bits for all the 3 colors?


    Why only 2 colors in 640? i thought it should be 640/3 r, 640/3 g,
    640/3 blue


    The image is not raw probably its processed after goin through a a/d.


    Regards,
    jo


    On Jun 16, 4:21 pm, "David J Taylor" <-
    this-bit.nor-this-bit.co.uk> wrote:
    > John wrote:
    > > Hi,
    > > Can any one tell me how the size of raw image computed?

    >
    > > say VGA - 640x480?

    >
    > > How may bytes will be one full frame?

    >
    > Typically:
    > 12 bits x 640 x 480
    >
    > > how much will be the size of each pixel?

    >
    > 12 bits, as it contains only one colour
    >
    > > How many pixels constitutes one full line in the frame?

    >
    > 640, but they will be 320 R + 320 G, or 320 B + 320 G pixels
    >
    > > How different is it for foveon cameras?

    >
    > > How much bytes will each line of the frame contain and what will be
    > > the
    > > pixel size in foveon cameras and ordinary cameras

    >
    > > Regards,
    > > Jm

    >
    > I hope that helps somewhat. I don't know how many bits Foveon uses, but
    > it records an RGB value at each pixel - but it does not have as many
    > pixels as a Bayer camera.
    >
    > Cheers,
    > David
    John, Jun 19, 2008
    #9
  10. John wrote:
    > Why 12 bits? isnt it 36 bits for all the 3 colors?


    Each pixel senses only /one/ colour.
    >
    > Why only 2 colors in 640? i thought it should be 640/3 r, 640/3 g,
    > 640/3 blue


    The classic Bayer pattern has twice as many green as red or blue, to
    improve resolution and snr.

    > The image is not raw probably its processed after goin through a a/d.
    >
    >
    > Regards,
    > jo


    That depends to which camera you are referring. Some process more than
    others.

    David
    David J Taylor, Jun 19, 2008
    #10
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