High-dynamic range photos

Discussion in 'NZ Computing' started by Lawrence D'Oliveiro, Aug 1, 2007.

  1. Microsoft wants its "HD Photo" format to be the new standard for
    representing high-dynamic range images
    <http://www.eweek.com/article2/0,1895,2164299,00.asp>.

    By the way, this statement

    A tremendous range of brightness to darkness in the display is also
    coming, and images taken with JPEG XR will access the capabilities of
    these displays, whereas images encoded with JPEG won't.

    is wrong. You can indeed do high dynamic range using plain old JPEG, just by
    applying a well-known signal-processing technique known as "oversampling".
    Sure, the resulting files may end up quite large, but that's what
    compression is for...
    Lawrence D'Oliveiro, Aug 1, 2007
    #1
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  2. Lawrence D'Oliveiro

    frederick Guest

    Lawrence D'Oliveiro wrote:
    > Microsoft wants its "HD Photo" format to be the new standard for
    > representing high-dynamic range images
    > <http://www.eweek.com/article2/0,1895,2164299,00.asp>.
    >
    > By the way, this statement
    >
    > A tremendous range of brightness to darkness in the display is also
    > coming, and images taken with JPEG XR will access the capabilities of
    > these displays, whereas images encoded with JPEG won't.
    >
    > is wrong. You can indeed do high dynamic range using plain old JPEG, just by
    > applying a well-known signal-processing technique known as "oversampling".
    > Sure, the resulting files may end up quite large, but that's what
    > compression is for...


    Jpeg holds only 8 bit colour data per rgb channel.
    Digital cameras with large pixels (typically dslrs) can record enough
    colour information to make use of 14 bit per channel raw format encoding
    (Most are 12, Canon's latest 1DsMkIII has a 14 bit analogue/digital
    converter).
    An HDR image might contain exposure data combined from multiple images,
    so typically programs that are used to create HDR images will output
    data in their native file format encoded as 16 bit per colour channel,
    or in 16 bit Tiff, or DNG format. 16bit uncompressed or losslessly
    compressed tiff files are huge.
    Once you've edited it, then to print or display it, a jpg is fine.
    But no - a jpeg may not be satisfactory to display a much wider dynamic
    range image possible with future monitors, problems already exist with
    integer rounding causing posterisation when editing images in 8 bit
    workspace, and the inability of jpg to hold the full dynamic range that
    digital sensors can capture is a problem now - let alone in the future.
    That said, I bet MS HD Photo format won't succeed as a standard.
    frederick, Aug 1, 2007
    #2
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  3. In message <1185959035.957679@ftpsrv1>, frederick wrote:

    > Lawrence D'Oliveiro wrote:
    >> Microsoft wants its "HD Photo" format to be the new standard for
    >> representing high-dynamic range images
    >> <http://www.eweek.com/article2/0,1895,2164299,00.asp>.
    >>
    >> By the way, this statement
    >>
    >> A tremendous range of brightness to darkness in the display is also
    >> coming, and images taken with JPEG XR will access the capabilities of
    >> these displays, whereas images encoded with JPEG won't.
    >>
    >> is wrong. You can indeed do high dynamic range using plain old JPEG, just
    >> by applying a well-known signal-processing technique known as
    >> "oversampling". Sure, the resulting files may end up quite large, but
    >> that's what compression is for...

    >
    > Jpeg holds only 8 bit colour data per rgb channel.


    You can increase that with oversampling.
    Lawrence D'Oliveiro, Aug 1, 2007
    #3
  4. Lawrence D'Oliveiro

    frederick Guest

    Lawrence D'Oliveiro wrote:
    > In message <1185959035.957679@ftpsrv1>, frederick wrote:
    >
    >> Lawrence D'Oliveiro wrote:
    >>> Microsoft wants its "HD Photo" format to be the new standard for
    >>> representing high-dynamic range images
    >>> <http://www.eweek.com/article2/0,1895,2164299,00.asp>.
    >>>
    >>> By the way, this statement
    >>>
    >>> A tremendous range of brightness to darkness in the display is also
    >>> coming, and images taken with JPEG XR will access the capabilities of
    >>> these displays, whereas images encoded with JPEG won't.
    >>>
    >>> is wrong. You can indeed do high dynamic range using plain old JPEG, just
    >>> by applying a well-known signal-processing technique known as
    >>> "oversampling". Sure, the resulting files may end up quite large, but
    >>> that's what compression is for...

    >> Jpeg holds only 8 bit colour data per rgb channel.

    >
    > You can increase that with oversampling.
    >

    Can you explain that further?
    I've never heard that before?
    Jpeg is 8 bit - and that's the limitation on D/R.
    How do you get more than 256 integers per channel from 8 bit jpeg?
    frederick, Aug 1, 2007
    #4
  5. In message <1185996980.640873@ftpsrv1>, frederick wrote:

    > Lawrence D'Oliveiro wrote:
    >> In message <1185959035.957679@ftpsrv1>, frederick wrote:
    >>
    >>> Lawrence D'Oliveiro wrote:
    >>>> Microsoft wants its "HD Photo" format to be the new standard for
    >>>> representing high-dynamic range images
    >>>> <http://www.eweek.com/article2/0,1895,2164299,00.asp>.
    >>>>
    >>>> By the way, this statement
    >>>>
    >>>> A tremendous range of brightness to darkness in the display is also
    >>>> coming, and images taken with JPEG XR will access the capabilities
    >>>> of these displays, whereas images encoded with JPEG won't.
    >>>>
    >>>> is wrong. You can indeed do high dynamic range using plain old JPEG,
    >>>> just by applying a well-known signal-processing technique known as
    >>>> "oversampling". Sure, the resulting files may end up quite large, but
    >>>> that's what compression is for...

    >>

    > Can you explain that further?


    Consider a square grid of 16*16 8-bit pixels. By summing different values
    together, you can get any total from 0 to 65280. This is not quite the
    65536 different levels you get with true 16-bit pixels, but it's close.
    (You could get 65536 different sums with 257 8-bit pixels, but it's a bit
    hard to arrange that number in any sensible kind of grid.)

    So each 16-bit pixel is represented by 256 8-bit pixels. This means, say, a
    1000-by-1000-pixel HDR image becomes a 16000-by-16000-pixel JPEG image.
    That sounds huge, but there should be a lot of repetition every 16 pixels,
    so compression should knock that down a bit.
    Lawrence D'Oliveiro, Aug 2, 2007
    #5
  6. Lawrence D'Oliveiro

    frederick Guest

    Lawrence D'Oliveiro wrote:
    > In message <1185996980.640873@ftpsrv1>, frederick wrote:
    >
    >> Lawrence D'Oliveiro wrote:
    >>> In message <1185959035.957679@ftpsrv1>, frederick wrote:
    >>>
    >>>> Lawrence D'Oliveiro wrote:
    >>>>> Microsoft wants its "HD Photo" format to be the new standard for
    >>>>> representing high-dynamic range images
    >>>>> <http://www.eweek.com/article2/0,1895,2164299,00.asp>.
    >>>>>
    >>>>> By the way, this statement
    >>>>>
    >>>>> A tremendous range of brightness to darkness in the display is also
    >>>>> coming, and images taken with JPEG XR will access the capabilities
    >>>>> of these displays, whereas images encoded with JPEG won't.
    >>>>>
    >>>>> is wrong. You can indeed do high dynamic range using plain old JPEG,
    >>>>> just by applying a well-known signal-processing technique known as
    >>>>> "oversampling". Sure, the resulting files may end up quite large, but
    >>>>> that's what compression is for...

    >> Can you explain that further?

    >
    > Consider a square grid of 16*16 8-bit pixels. By summing different values
    > together, you can get any total from 0 to 65280. This is not quite the
    > 65536 different levels you get with true 16-bit pixels, but it's close.
    > (You could get 65536 different sums with 257 8-bit pixels, but it's a bit
    > hard to arrange that number in any sensible kind of grid.)
    >
    > So each 16-bit pixel is represented by 256 8-bit pixels. This means, say, a
    > 1000-by-1000-pixel HDR image becomes a 16000-by-16000-pixel JPEG image.
    > That sounds huge, but there should be a lot of repetition every 16 pixels,
    > so compression should knock that down a bit.


    LOL - and you'd have to get special software to view it - kind of silly
    when there are 16bit image file formats around already.
    And I shudder to think how long it would take to compress and decompress
    a typical image file of say 4000x3000 pixels using that method when it
    holds a few tens of thousands of GB of data!
    frederick, Aug 2, 2007
    #6
  7. Lawrence D'Oliveiro

    Gordon Guest

    On Wed, 01 Aug 2007 21:09:36 +1200, frederick wrote:

    [snip]

    > That said, I bet MS HD Photo format won't succeed as a standard.


    The irony is that that the Joint Pictures Group formed and gave us all
    the standard while MS was some place else. read the boat has sailed, 99%
    of the people are on it.

    BTW jpg is for us all to sahre, as opposed to $$$$$$$$$$$$$$$$$$$$$$$$
    for one only.
    Gordon, Aug 4, 2007
    #7
  8. On Aug 4, 6:35 am, Gordon <> wrote:
    > On Wed, 01 Aug 2007 21:09:36 +1200, frederick wrote:
    >
    > [snip]
    >
    > > That said, I bet MS HD Photo format won't succeed as a standard.

    >
    > The irony is that that the Joint Pictures Group formed and gave us all
    > the standard while MS was some place else. read the boat has sailed, 99%
    > of the people are on it.

    [snip]

    And now JPEG, apparently basically the same group, is considering HD
    Photo as a possible extra JPEG standard. (JPEG XR).

    I'm tracking it here:
    http://www.barrypearson.co.uk/articles/hdp/

    It does appear to have some genuine technical advantages over JPEG,
    and my tests suggest that it can typically compress to about 60% of
    the size with the same image quality.
    http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm

    But it has lots more than that. And it appears to be a very effective
    lossless format too.

    --
    Barry Pearson
    http://www.barrypearson.co.uk/photography/
    Barry Pearson, Aug 5, 2007
    #8
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