NEWS: HD Photo to become JPEG XR

Discussion in 'Digital Photography' started by John Navas, Nov 26, 2007.

  1. John Navas

    John Navas Guest

    <http://www.news.com/8301-13580_3-9810024-39.html>

    A new attempt to provide a higher-end sequel to the ubiquitous JPEG
    image standard is officially under way.

    The multiple countries participating in the Joint Photographic
    Experts Group, which created the JPEG standard, have approved an
    effort to make Microsoft's HD Photo format a standard called JPEG XR,
    said Bill Crow, who has led Microsoft's HD Photo effort and who just
    took over the company's Microsoft Live Labs Seadragon imaging
    project. XR stands for "extended range," a reference to the format's
    ability to show a wider and finer range of tonal gradations and a
    richer color palette.

    "The country vote is done, and it passed," Crow said. "That means the
    International JPEG committee has decided to go ahead and create the
    standard. Now it's just a process of doing that work," a process that
    will begin later this month in a meeting in Kobe, Japan.

    The move is an important step in the transformation of the photo
    format from an in-house technology called Windows Media Photo to a
    neutral format more likely to be palatable to companies that don't
    want to be beholden to Microsoft.

    However, the move also means that Microsoft will have to be more
    patient with its hopes to get HD Photo to catch on more broadly.
    Standardization "typically takes around a year," Crow said.

    ...

    In Microsoft's view, HD Photo also offers better compression and
    support for in-camera image processing. It's built into Windows
    Vista, but Microsoft offers the software development kit to implement
    the technology free and with no royalty constraints. Image-editing
    powerhouse Adobe Systems has voiced support for the format.

    [MORE]


    MY TAKE: JPEG 2000 hasn't exactly taken the market by storm, and a new
    more capable format is badly needed, so let's hope JPEG XR takes off!

    --
    Best regards,
    John Navas
    Panasonic DMC-FZ8 (and several others)
    John Navas, Nov 26, 2007
    #1
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  2. John Navas

    John Navas Guest

    Why JPEG XR is badly needed:

    The problem is 8-bit (per channel) JPEG. Although non-linearity gives it
    roughly 11 stop dynamic range, 8-bit luminosity resolution is more
    limited than many camera sensors (often 10-12 bits). While 8-bit JPEG is
    fine for scenes with lower luminosity range, more bits are needed for
    best results with higher luminosity range. This is a major, if not the
    major, reason to shoot RAW.

    * An alternative would be 12-bit JPEG, but there's too little support
    for that to be practical.

    * Another alternative is JPEG 2000, which also has a useful lossless
    mode, but it's still not widely supported, has EXIF issues, has
    potential patent issues, and puts a higher computational burden on the
    camera processor than JPEG.

    * Yet another alternative would be Adobe DNG as an alternative to
    proprietary camera RAW, but major camera manufacturers seem resultant to
    adopt it.

    * Lastly there's Microsoft's JPEG XR (HD Photo), which is more like JPEG
    than JPEG 2000 in terms of computational burden with compression
    efficiency comparable to JPEG 2000, but is not yet standardized.

    Until this is sorted out, RAW remains an important tool for scenes with
    higher luminosity range, despite its drawbacks. I personally don't use
    RAW often, but I do sometimes use it.

    --
    Best regards,
    John Navas
    Panasonic DMC-FZ8 (and several others)
    John Navas, Nov 26, 2007
    #2
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  3. John Navas

    FYI2 Guest

    Editors, Viewers, Browsers, and Applications that are already, or will soon be,
    HD PHoto and/or JPEG XR compatible:


    >>>Editors:


    PhotoLine http://www.pl32.com - complete 32-bit editor
    (HD Photo format implemented for many months now)





    >>>Viewers:







    >>>Browsers








    >>>Misc. Applications:






    (feel free to add yours as you find them)
    FYI2, Nov 26, 2007
    #3
  4. John Navas <> writes:

    >MY TAKE: JPEG 2000 hasn't exactly taken the market by storm, and a new
    >more capable format is badly needed, so let's hope JPEG XR takes off!


    One of the things that made the original JPEG format supported by just
    about every imaging program under the sun was the availability of the
    royalty-free JPEG library produced by the Independent JPEG Group
    (basically Tom Lane). Every basement application author could just get
    the code and drop it into their application and start supporting JPEG.
    I don't think there were any licencing documents and certainly no
    payment involved.

    Can Microsoft bring itself to release something similarly unencumbered
    if it's based on their own code? Or will it take someone like Tom to
    produce an independent implementation before the format becomes widely
    adopted?

    Dave
    Dave Martindale, Nov 26, 2007
    #4
  5. John Navas

    Douglas Guest

    "Dave Martindale" <> wrote in message
    news:fifbek$k4m$...
    > John Navas <> writes:
    >
    >>MY TAKE: JPEG 2000 hasn't exactly taken the market by storm, and a new
    >>more capable format is badly needed, so let's hope JPEG XR takes off!

    >
    > One of the things that made the original JPEG format supported by just
    > about every imaging program under the sun was the availability of the
    > royalty-free JPEG library produced by the Independent JPEG Group
    > (basically Tom Lane). Every basement application author could just get
    > the code and drop it into their application and start supporting JPEG.
    > I don't think there were any licencing documents and certainly no
    > payment involved.
    >
    > Can Microsoft bring itself to release something similarly unencumbered
    > if it's based on their own code? Or will it take someone like Tom to
    > produce an independent implementation before the format becomes widely
    > adopted?
    >
    > Dave


    They (Microsoft) already have given the code out freely.
    Douglas, Nov 27, 2007
    #5
  6. John Navas schrieb:

    For first, this news is old news. It dates back to the JPEG meeting in Lausanne this
    summer.

    > Why JPEG XR is badly needed:
    >
    > The problem is 8-bit (per channel) JPEG. Although non-linearity gives it
    > roughly 11 stop dynamic range, 8-bit luminosity resolution is more
    > limited than many camera sensors (often 10-12 bits). While 8-bit JPEG is
    > fine for scenes with lower luminosity range, more bits are needed for
    > best results with higher luminosity range. This is a major, if not the
    > major, reason to shoot RAW.


    Probably, probably not. Another issue is - at least in my understanding - that
    photographers feel that they "loose" possibilities by lossy compression, i.e.
    image content is gone forever. I wouldn't say "badly" either. There are lots
    of proper alternatives that just wait to be used, you mentioned them.

    > * An alternative would be 12-bit JPEG, but there's too little support
    > for that to be practical.


    That goes, however, for all alternatives as well. Actually, the IJG seems
    to support 12bit by now.

    > * Another alternative is JPEG 2000, which also has a useful lossless
    > mode, but it's still not widely supported, has EXIF issues, has
    > potential patent issues, and puts a higher computational burden on the
    > camera processor than JPEG.


    The EXIF issues are currently addressed. Actually, the issue can be solved
    rather easily as JPEG2000 has more than enough room to include meta-data.
    You are correct when saying that it has complexity issues, though. The
    second major error made during its standardization.

    > * Yet another alternative would be Adobe DNG as an alternative to
    > proprietary camera RAW, but major camera manufacturers seem resultant to
    > adopt it.


    That's not too unlikely to happen with any new format. Actually, Japanese
    camera vendors don't seem - in my reception - feel too hot about JPEG-XR
    either.

    > * Lastly there's Microsoft's JPEG XR (HD Photo), which is more like JPEG
    > than JPEG 2000 in terms of computational burden with compression
    > efficiency comparable to JPEG 2000, but is not yet standardized.


    It's currently undergoing standardization, however, saying that it can compete with
    JPEG2000 in terms of compression performance is IMHO highly overstating its powers. In
    fact, from the tests performed, I somewhere sort it near or sometimes even below
    baseline JPEG, depending on image content. Note that JPEG-XR is not yet final,
    so things will hopefully change to the better, and that for proper tests, one
    also has to check with HDR images from the market JPEG-XR actually targets at,
    so beware - this is just the status quo. On the other hand, being more critical to
    MS press releases won't hurt, either. The best you can do is test yourself.

    > Until this is sorted out, RAW remains an important tool for scenes with
    > higher luminosity range, despite its drawbacks. I personally don't use
    > RAW often, but I do sometimes use it.


    The major drawback is its lack of standardization. The problem seems that camera
    vendors prefer to bind their customers instead of making images interchangeable.
    I don't see why JPEG-XR would change their position, but that's all my guesswork.
    Otherwise, it would have been easy just to approach the JPEG to standardize *some*
    type of raw format - it is IMHO just not desirable for the vendors.

    So long,
    Thomas
    Thomas Richter, Nov 27, 2007
    #6
  7. John Navas

    John Navas Guest

    On Tue, 27 Nov 2007 12:51:09 +0100, Thomas Richter
    <-berlin.de> wrote in
    <fih0em$999$-stuttgart.de>:

    >John Navas schrieb:
    >
    >For first, this news is old news. It dates back to the JPEG meeting in Lausanne this
    >summer.


    Not that it matters, but the latest developments are much more recent
    than that -- the article I posted was published early this month.

    >> Why JPEG XR is badly needed:
    >>
    >> The problem is 8-bit (per channel) JPEG. Although non-linearity gives it
    >> roughly 11 stop dynamic range, 8-bit luminosity resolution is more
    >> limited than many camera sensors (often 10-12 bits). While 8-bit JPEG is
    >> fine for scenes with lower luminosity range, more bits are needed for
    >> best results with higher luminosity range. This is a major, if not the
    >> major, reason to shoot RAW.

    >
    >Probably, probably not. Another issue is - at least in my understanding - that
    >photographers feel that they "loose" possibilities by lossy compression, i.e.
    >image content is gone forever. I wouldn't say "badly" either. There are lots
    >of proper alternatives that just wait to be used, you mentioned them.


    It all depends. JPEG compression is indeed poor in some cameras with
    RAW and you're apparently expected to shoot RAW, but is quite good in
    other cameras.

    >> * Another alternative is JPEG 2000, which also has a useful lossless
    >> mode, but it's still not widely supported, has EXIF issues, has
    >> potential patent issues, and puts a higher computational burden on the
    >> camera processor than JPEG.

    >
    >The EXIF issues are currently addressed. Actually, the issue can be solved
    >rather easily as JPEG2000 has more than enough room to include meta-data.


    The problem is that there are competing solutions, rather than a single
    standard.

    >You are correct when saying that it has complexity issues, though. The
    >second major error made during its standardization.


    I think it was probably a fatal flaw.

    >> * Yet another alternative would be Adobe DNG as an alternative to
    >> proprietary camera RAW, but major camera manufacturers seem resultant to
    >> adopt it.

    >
    >That's not too unlikely to happen with any new format. Actually, Japanese
    >camera vendors don't seem - in my reception - feel too hot about JPEG-XR
    >either.


    Microsoft and HP have considerable market clout, Adobe has voiced
    support, and inclusion in Vista is a big deal. Samsung is a serious up
    and comer, and appears to be interested. Likewise Panasonic. Don't
    know about Canon, Sony, Nikon, and Olympus.

    >It's currently undergoing standardization, however, saying that it can compete with
    >JPEG2000 in terms of compression performance is IMHO highly overstating its powers. In
    >fact, from the tests performed, I somewhere sort it near or sometimes even below
    >baseline JPEG, depending on image content. Note that JPEG-XR is not yet final,
    >so things will hopefully change to the better, and that for proper tests, one
    >also has to check with HDR images from the market JPEG-XR actually targets at,
    >so beware - this is just the status quo. On the other hand, being more critical to
    >MS press releases won't hurt, either. The best you can do is test yourself.


    I have, and I've been impressed.

    --
    Best regards,
    John Navas
    Panasonic DMC-FZ8 (and several others)
    John Navas, Nov 27, 2007
    #7
  8. John Navas schrieb:

    >> For first, this news is old news. It dates back to the JPEG meeting in Lausanne this
    >> summer.

    >
    > Not that it matters, but the latest developments are much more recent
    > than that -- the article I posted was published early this month.


    Believe me, I'm sitting at the source. This goes back to last summer,
    really.

    >> The EXIF issues are currently addressed. Actually, the issue can be solved
    >> rather easily as JPEG2000 has more than enough room to include meta-data.

    >
    > The problem is that there are competing solutions, rather than a single
    > standard.


    Ehem. I am talking about a standardized solution, really. (-:

    >> You are correct when saying that it has complexity issues, though. The
    >> second major error made during its standardization.

    >
    > I think it was probably a fatal flaw.


    Probably, yes.

    >>> * Yet another alternative would be Adobe DNG as an alternative to
    >>> proprietary camera RAW, but major camera manufacturers seem resultant to
    >>> adopt it.

    >> That's not too unlikely to happen with any new format. Actually, Japanese
    >> camera vendors don't seem - in my reception - feel too hot about JPEG-XR
    >> either.

    >
    > Microsoft and HP have considerable market clout, Adobe has voiced
    > support, and inclusion in Vista is a big deal. Samsung is a serious up
    > and comer, and appears to be interested. Likewise Panasonic. Don't
    > know about Canon, Sony, Nikon, and Olympus.


    All I know is the voting of the Japanese, Singapure and Korean
    delegation on this...

    >> It's currently undergoing standardization, however, saying that it can compete with
    >> JPEG2000 in terms of compression performance is IMHO highly overstating its powers. In
    >> fact, from the tests performed, I somewhere sort it near or sometimes even below
    >> baseline JPEG, depending on image content. Note that JPEG-XR is not yet final,
    >> so things will hopefully change to the better, and that for proper tests, one
    >> also has to check with HDR images from the market JPEG-XR actually targets at,
    >> so beware - this is just the status quo. On the other hand, being more critical to
    >> MS press releases won't hurt, either. The best you can do is test yourself.

    >
    > I have, and I've been impressed.


    I have, and I've been disappointed - how did you do your comparisons if
    I may ask?
    Actually, we made objective and subjective tests (i.e. tested with
    various mathematical image quality metrics, and also tested with test
    observers), and the results were pretty much comparable, and - as I said
    - disappointing. It *did* often preform better than JPEG, but that's not
    too hard in first place. Comparing with an arithmetic coding enabled
    JPEG (which is just another option nobody uses in traditional JPEG)
    showed again different results.
    The results so far fit to my own visual impression: HDPhoto seems to
    introduce both blocking and blurring artefacts I don't want to see. When
    making comparisons, you should make sure you really compress to the same
    target file size, otherwise you're running into an apples-vs-oranges
    problem. The "quality" scale of HDPhoto is different from the JPEG one.
    When really placing images compressed with HDPhoto and JPEG side by
    side, it really depends on the image content and on personal taste which
    one is better, or which one is worse. Things change noticably when
    comparing with more advanced codecs.

    Anyhow, as I already said earlier, HDPhoto has hopefully enough
    potential to improve its performance, and we haven't really measured
    anything beyond 8bpp either, so all of that needs to be considered. All
    I doing is presenting the current state of affairs, and the state of
    affairs is complicated, unfortunately.

    So long,
    Thomas
    Thomas Richter, Nov 28, 2007
    #8
  9. On Nov 27, 11:51 am, Thomas Richter <-berlin.de> wrote:
    > John Navas schrieb:

    [snip]
    > > * Lastly there's Microsoft's JPEG XR (HD Photo), which is more like JPEG
    > > than JPEG 2000 in terms of computational burden with compression
    > > efficiency comparable to JPEG 2000, but is not yet standardized.

    >
    > It's currently undergoing standardization, however, saying that it can compete with
    > JPEG2000 in terms of compression performance is IMHO highly overstating its powers. In
    > fact, from the tests performed, I somewhere sort it near or sometimes even below
    > baseline JPEG, depending on image content. Note that JPEG-XR is not yet final,
    > so things will hopefully change to the better, and that for proper tests, one
    > also has to check with HDR images from the market JPEG-XR actually targets at,
    > so beware - this is just the status quo. On the other hand, being more critical to
    > MS press releases won't hurt, either. The best you can do is test yourself.


    I have published my own tests at the page below. My conclusion from
    these (admittedly limited) tests was:

    "For any given set of quality values, the HD Photo and JPEG 2000 files
    were about the same size, and significantly smaller than the JPEG
    file". ("Half the size" would be a fair generalisation, and at that
    level probably fewer nasty artefacts). The basis for these conclusions
    is at the following page - I won't repeat them here:
    http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm

    > > Until this is sorted out, RAW remains an important tool for scenes with
    > > higher luminosity range, despite its drawbacks. I personally don't use
    > > RAW often, but I do sometimes use it.

    >
    > The major drawback is its lack of standardization. The problem seems that camera
    > vendors prefer to bind their customers instead of making images interchangeable.
    > I don't see why JPEG-XR would change their position, but that's all my guesswork.
    > Otherwise, it would have been easy just to approach the JPEG to standardize *some*
    > type of raw format - it is IMHO just not desirable for the vendors.


    There IS an ISO standard raw file format. ISO 12234-2 (TIFF/EP). (It
    became an ISO standard in 2001, and some manufacturers such as Canon
    and Nikon based their own raw file formats on it). The problem is that
    it was never really fit for the purpose of standardised interchange,
    and it has become out-of-date. (In effect, DNG, also based on that
    standard, is ISO 12234-2 brought up-to-date and made fit for purpose).

    ISO are revising ISO 12234-2, and Adobe have given them permission to
    use the features of DNG in the revision. (Just as they gave ISO
    permission to use TIFF in the original version of ISO 12234-2).

    Given that ISO's TC42 WG18 has responsibility for TIFF/EP, it would be
    diversionary for another working group to "compete" to standardise a
    raw file format. Far better, surely, for all standards bodies and
    working groups to concentrate on one standard, especially if it can
    based on a format (DNG) that is supported in some way by nearly 200
    products of various kinds. (I would like to see the revised ISO
    12234-2 either BE DNG, or be compatible with DNG sufficiently for
    products to work with a common subset).
    http://www.barrypearson.co.uk/articles/dng/products.htm

    --
    Barry Pearson
    http://www.barrypearson.co.uk/photography/
    Barry Pearson, Nov 29, 2007
    #9
  10. On Nov 28, 9:44 am, Thomas Richter <-berlin.de> wrote:
    > John Navas schrieb:
    >
    > >> For first, this news is old news. It dates back to the JPEG meeting in Lausanne this
    > >> summer.

    >
    > > Not that it matters, but the latest developments are much more recent
    > > than that -- the article I posted was published early this month.

    >
    > Believe me, I'm sitting at the source. This goes back to last summer,
    > really.

    [snip]

    Here is some history:
    http://www.barrypearson.co.uk/articles/hdp/history.htm

    The work item to standardise it dated to July, subject first to a
    ballot. (This was the result of an introduction of HD Photo to the
    group last April).

    The more recent news (November) is that the ballot decided to go ahead
    with the standardisation.

    --
    Barry Pearson
    http://www.barrypearson.co.uk/photography/
    Barry Pearson, Nov 29, 2007
    #10
  11. Barry Pearson schrieb:

    > I have published my own tests at the page below. My conclusion from
    > these (admittedly limited) tests was:
    >
    > "For any given set of quality values, the HD Photo and JPEG 2000 files
    > were about the same size, and significantly smaller than the JPEG
    > file". ("Half the size" would be a fair generalisation, and at that
    > level probably fewer nasty artefacts). The basis for these conclusions
    > is at the following page - I won't repeat them here:
    > http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm



    How do you define "quality"? What is a "quality value"? You have to be
    *very* careful defining terms, or you're likely comparing apples to
    oranges. Sorry to be picky, but one has to be pretty careful when
    testing.

    Some typical mistakes (not saying that you did it, just things to watch out for):

    The "quality" value of HDPhoto has nothing to do with the "quality" value of
    JPEG. JPEG2000 doesn't even define something like that, but lets you choose the
    target file size. Vendors might prefer to offer a "quality" setting, but that's
    then entirely vendor defined.

    Others measure "quality" in terms of PSNR (peak signal to noise ratio), then
    often logarithmic in dB. This "quality" relates pretty badly to "visual impression",
    it is easy to generate two images with the same dB as "quality", one of them
    looking great, the other looking unacceptable. Better metrics exist, none of them
    is perfect, but most of them are notably better than PSNR.

    This said, our tests do the following:

    i) Pick a test image set, for all images in the set:
    ii) compress the image to quality level x of HDPhoto
    iii) measure the file size returned by HDPhoto
    iv) compress the same image to the same file size with JPEG2000 (yes, JPEG2000 can
    do that)
    v) Use either an objective visual quality metric (we've used M-SSIM, VDP and PQS)
    or run subjective tests (with people actually looking at the images), and by that
    define a quality.

    vi) compile results by plotting "perceived" or "objectively measured" quality over
    output rate.

    When doing this test (and not measuring PSNR and not adjusting obscure quality
    settings), you really compare apples to apples. Unfortunately, and that's what I
    said, HDPhoto doesn't at all perform very well. And, as said, I hope that this is
    fixable, but the current version is not.

    Furthermore, please also note that the *current* test image set is still limited,
    more tests are to be done.

    >> The major drawback is its lack of standardization. The problem seems that camera
    >> vendors prefer to bind their customers instead of making images interchangeable.
    >> I don't see why JPEG-XR would change their position, but that's all my guesswork.
    >> Otherwise, it would have been easy just to approach the JPEG to standardize *some*
    >> type of raw format - it is IMHO just not desirable for the vendors.

    >
    > There IS an ISO standard raw file format. ISO 12234-2 (TIFF/EP). (It
    > became an ISO standard in 2001, and some manufacturers such as Canon
    > and Nikon based their own raw file formats on it). The problem is that
    > it was never really fit for the purpose of standardised interchange,
    > and it has become out-of-date. (In effect, DNG, also based on that
    > standard, is ISO 12234-2 brought up-to-date and made fit for purpose).
    >
    > ISO are revising ISO 12234-2, and Adobe have given them permission to
    > use the features of DNG in the revision. (Just as they gave ISO
    > permission to use TIFF in the original version of ISO 12234-2).
    >
    > Given that ISO's TC42 WG18 has responsibility for TIFF/EP, it would be
    > diversionary for another working group to "compete" to standardise a
    > raw file format. Far better, surely, for all standards bodies and
    > working groups to concentrate on one standard, especially if it can
    > based on a format (DNG) that is supported in some way by nearly 200
    > products of various kinds. (I would like to see the revised ISO
    > 12234-2 either BE DNG, or be compatible with DNG sufficiently for
    > products to work with a common subset).


    Thanks for the pointers to TC42 (I'm SC29, so there you go), I'll ask
    there. In my impression, TC42 doesn't really have too much support
    or acceptance from the camera vendors, but I'm (currently) only watching
    this from the outside, so I cannot really say for sure. I'd be personally
    happy if any type of "raw format" standardization would arrive at a format
    that is really accepted and that makes image data interchangeable, but
    probably there are too many sensor types, or too many trade secrets - I don't
    know.

    So long,
    Thomas
    Thomas Richter, Nov 30, 2007
    #11
  12. On Nov 30, 7:48 am, Thomas Richter <-berlin.de> wrote:
    > Barry Pearson schrieb:
    >
    > > I have published my own tests at the page below. My conclusion from
    > > these (admittedly limited) tests was:

    >
    > > "For any given set of quality values, the HD Photo and JPEG 2000 files
    > > were about the same size, and significantly smaller than the JPEG
    > > file". ("Half the size" would be a fair generalisation, and at that
    > > level probably fewer nasty artefacts). The basis for these conclusions
    > > is at the following page - I won't repeat them here:
    > >http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm

    >
    > How do you define "quality"? What is a "quality value"? You have to be
    > *very* careful defining terms, or you're likely comparing apples to
    > oranges. Sorry to be picky, but one has to be pretty careful when
    > testing.


    The term "quality values", as I used it, is defined on the above page.
    As I said, I won't repeat it here. Specifically, at:
    http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm#results

    [snip]
    > > Given that ISO's TC42 WG18 has responsibility for TIFF/EP, it would be
    > > diversionary for another working group to "compete" to standardise a
    > > raw file format. Far better, surely, for all standards bodies and
    > > working groups to concentrate on one standard, especially if it can
    > > based on a format (DNG) that is supported in some way by nearly 200
    > > products of various kinds. (I would like to see the revised ISO
    > > 12234-2 either BE DNG, or be compatible with DNG sufficiently for
    > > products to work with a common subset).

    >
    > Thanks for the pointers to TC42 (I'm SC29, so there you go), I'll ask
    > there. In my impression, TC42 doesn't really have too much support
    > or acceptance from the camera vendors, but I'm (currently) only watching
    > this from the outside, so I cannot really say for sure. I'd be personally
    > happy if any type of "raw format" standardization would arrive at a format
    > that is really accepted and that makes image data interchangeable, but
    > probably there are too many sensor types, or too many trade secrets - I don't
    > know.


    Some camera vendors (eg. Canon, Nikon) based their raw file formats on
    ISO 12234-2 from TC42. Indeed, NEF files identify the TIFF/EP version
    used.

    There are actually not many sensor types - they are mostly of few
    general types (eg. Bayer, Fujifilm SuperCCD) but with many parametric
    differences that can be caterd for. That is how DNG works, as shown
    at:
    http://www.barrypearson.co.uk/articles/dng/innovation.htm#examples

    One "trade secret" problem is with Foveon/Sigma X3F files, where
    documenting their details would identify internal details of the
    Foveon software used by some raw converters. So DNG only supports X3F
    images after using some Foveon software to process it, and doesn't
    hold its raw state.

    Camera manufacturers COULD use a common standard if they chose, (with
    a possible exception for Foveon), which is why a number of niche and
    minority manufacturers support DNG. (My Pentax K10D gives an option
    whether to use PEF or DNG, and gives the same results either way).
    http://www.barrypearson.co.uk/articles/dng/products.htm#manufacturers

    --
    Barry Pearson
    http://www.barrypearson.co.uk/photography/
    Barry Pearson, Nov 30, 2007
    #12
  13. Barry Pearson wrote:
    > On Nov 30, 7:48 am, Thomas Richter <-berlin.de> wrote:
    >> Barry Pearson schrieb:
    >>
    >>> I have published my own tests at the page below. My conclusion from
    >>> these (admittedly limited) tests was:
    >>> "For any given set of quality values, the HD Photo and JPEG 2000 files
    >>> were about the same size, and significantly smaller than the JPEG
    >>> file". ("Half the size" would be a fair generalisation, and at that
    >>> level probably fewer nasty artefacts). The basis for these conclusions
    >>> is at the following page - I won't repeat them here:
    >>> http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm

    >> How do you define "quality"? What is a "quality value"? You have to be
    >> *very* careful defining terms, or you're likely comparing apples to
    >> oranges. Sorry to be picky, but one has to be pretty careful when
    >> testing.

    >
    > The term "quality values", as I used it, is defined on the above page.
    > As I said, I won't repeat it here. Specifically, at:
    > http://www.barrypearson.co.uk/articles/hdp/analysis_lossy.htm#results


    Well, your quality settings seem to be very low - unrealistically low.
    You do not use those rates in real images (or, I actually wouldn't want
    to (-:) The algorithms might and will behave differently for higher
    quality. JPEG2000 doesn't have a "quality" at all, it's a vendor defined
    thing. May I ask which vendor you picked? Without that, a "quality"
    makes no sense at all.

    How do you define "examine the differences"? This is not well-defined,
    what do I do with these histograms to get a "quality"? Do you
    want to limit the maximum error? (Mathematically, this is the l^infinity
    metric). Not really a very usable metric - a single wrong pixel can
    ruin it, even though if that is in a suitable image part, you wouldn't
    even see it. I've here images where the absolute error for JPEG is
    pretty huge, but the image is pretty fine. It really depends *where*
    this error is in the picture. If you look at the "mean" error, (guessing
    that this is the *mean square error*) then that's basically PSNR (which
    I already mentioned). It is a fairly bad metric, but a popular one with
    known deficiencies.

    May I suggest a different way of handling it? Measuring the *file size*
    is much easier. Try to adjust compression parameters such that for
    all three methods, you get approximately the same size. Then inspect
    images visually or by objective metrics. I can send you code for that.

    Defining the quality from the histogram is unfortunately not very
    reasonable as well - you neglect a lot, if not all visual effects known.
    Especially at bitrates *that* low, a lot of nasty things happen.

    Examples: Human observers are more sensitive to specific spatial image
    frequencies than others (that's also the reason why the JPEG-1 default
    quantization matrix looks so weird), are less sensitive to color than to
    luminance, and are less sensitive to errors when those errors are in
    "noisy" image regions, i.e. errors can be easily hidden behind image
    structures.

    This is also the reason why every sensible image metric requires
    careful "subjective" testing, i.e. ask a lot of people on their
    opinion of the quality, then check how sensible the metric can predict
    those numbers.

    > Some camera vendors (eg. Canon, Nikon) based their raw file formats on
    > ISO 12234-2 from TC42. Indeed, NEF files identify the TIFF/EP version
    > used.
    >
    > There are actually not many sensor types - they are mostly of few
    > general types (eg. Bayer, Fujifilm SuperCCD) but with many parametric
    > differences that can be caterd for. That is how DNG works, as shown
    > at:
    > http://www.barrypearson.co.uk/articles/dng/innovation.htm#examples


    Thanks for that, I haven't really looked into DNG, though I was
    aware of its existence (but only that and barely more).

    > One "trade secret" problem is with Foveon/Sigma X3F files, where
    > documenting their details would identify internal details of the
    > Foveon software used by some raw converters. So DNG only supports X3F
    > images after using some Foveon software to process it, and doesn't
    > hold its raw state.
    >
    > Camera manufacturers COULD use a common standard if they chose, (with
    > a possible exception for Foveon), which is why a number of niche and
    > minority manufacturers support DNG. (My Pentax K10D gives an option
    > whether to use PEF or DNG, and gives the same results either way).
    > http://www.barrypearson.co.uk/articles/dng/products.htm#manufacturers


    Thus, asking frankly, why don't they? (-:

    So long,
    Thomas
    Thomas Richter, Nov 30, 2007
    #13
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