Adobe RGB V sRGB

Discussion in 'Digital Photography' started by Russell, Jun 20, 2005.

  1. Russell

    Celcius Guest

    "Go Read" is like "Go fetch!"
    I suppose you may know a lot about photography, but very little about
    education. I suppose this is farfetched and utterly lost on you.
    Celcius, Sep 11, 2005
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  2. I've taught graduate level courses in College. "Go Read" is what
    Graduate Students are told to do. We would hand out things called
    "Reading Lists" at the start of the Semester and students were
    expected to read all the material on them and be responsible for it
    regardless whether it was discussed in class or not.

    If you really want to know something you'll go read it not sit around
    and wait for others to waste time telling you what they learned by

    I don't believe in treating fools lightly, either.

    "...bray a fool in a morter with wheat,
    yet shall not his folly be beaten out of him;.."

    "The Marriage of Heaven and Hell"
    William Blake
    John A. Stovall, Sep 11, 2005
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  3. Russell

    DD Guest

    I think you are a liar. You rather sound like a newbie
    spending time in a library and do not really know
    how to answer questions like those asked.
    A group like this can do without your kind.

    DD, Sep 11, 2005
  4. Take a look at this;f=5;t=1604
    Lester Wareham, Sep 11, 2005
  5. Russell

    Celcius Guest

    Celcius, Sep 11, 2005
  6. Here's why and you don't have to register. Like I said earlier larger
    color Gamut.


    "...bray a fool in a morter with wheat,
    yet shall not his folly be beaten out of him;.."

    "The Marriage of Heaven and Hell"
    William Blake
    John A. Stovall, Sep 11, 2005
  7. Russell

    Celcius Guest

    Celcius, Sep 11, 2005
  8. Russell

    Bill Tuthill Guest

    Adobe RGB was designed to contain both RGB (monitor) colorspace(s)
    and CMYK colorspaces for offset printing.

    If you don't do offset printing, the CMYK colorspaces are not useful.

    So using Adobe RGB complicates your workflow, introduces colorspace
    conversion problems, and doesn't improve your results for web images
    or for images printed on Fuji Frontier, an SRGB-compliant device.
    Possibly Adobe RGB will allow you to make better inkjet prints.

    ProPhoto RGB can increase color gamut and especially dynamic range,
    an area where digital photos often suffer.
    Bill Tuthill, Sep 12, 2005
  9. Never mind John has put some of the links in.

    If you are interested there is quite a lengthy discussion on the pros and
    cons in the link I sent you.

    Its a good forum so it might be worth persisting.
    Lester Wareham, Sep 12, 2005
  10. Russell

    Hecate Guest

    Actually, that should read: If you don't do printing. Printers print
    using CMYK, regardless of whether the files they get are RGB or CMYK.

    So, if you don't do printing, ProPhoto RGB is fine. If you do...


    Hecate - The Real One

    Fashion: Buying things you don't need, with money
    you don't have, to impress people you don't like...
    Hecate, Sep 13, 2005
  11. Russell

    John Bean Guest

    That makes no sense. Adobe RGB is preferred for printing
    *only* because it's a larger space than sRGB (which will
    clip some CMYK colours). ProPhoto RGB is bigger still and
    will almost certainly not clip the printing gamut.

    So why do you believe ProPhoto RGB is unsuitable for
    John Bean, Sep 13, 2005
  12. Russell

    Hecate Guest

    Actually, it makes perfect sense if you realise what each colour space
    encompasses. Look at the 3D colour space maps which show the actual
    colour spaces covered. If you compare the three you mention, sRGB is
    useless except for web images because it narrows the space and at the
    same time has large areas of clipping when printing because it doesn't
    match the CMYK colour space at all well. OTOH, ProPhotoRGB has a
    wider colour space than Adobe RGB *but* it also does not match the
    CMYK colour space very well. AdobeRGB, OTOH, matches the CMYK colour
    space more closely and will result in less clipping (i.e. less out of
    gamut colours) when printing - especially in the yellows and greens
    which landscape photographers, for example, will find important.

    It's all very well having a wider colour space such as ProPhoto, but
    it's not much use if those colours disappear as soon as you print.


    Hecate - The Real One

    Fashion: Buying things you don't need, with money
    you don't have, to impress people you don't like...
    Hecate, Sep 14, 2005
  13. Russell

    dj_nme Guest

    John Bean wrote:
    Ther is a chance of posterisation of tones that are reproducable on a
    CYMK printer.
    Perhaps the effect will not be as vile as converting an image from VGA
    to CGA display colour gamut, but there could be some un-expected
    banding or colour splotches caused by the printing software converting
    from a larger colour space to a smaller colour space and it just not
    knowing what to do.

    It is also assuming that the origianl image was taken with a digital
    camera or scanner that can save in the ProPhoto RGB colour space.
    To the best of my knowledge, none exist (at this point in time) and so
    the colour workflow may look something like this: image taken as RAW
    file in camera, converted to a Adobe RGB by the RAW software, opened in
    a graphics program and then converted to ProPhoto RGB and saved and
    Going from smaller to larger colour space wont have a chance to
    posterise, because all of the info from the smaller fits into the
    larger colour space.
    Going the other way (for example printing out an image), has the
    potential to cause banding/posterisation because more colour info has
    to be squashed back onto a smaller colour space which just can't handle
    the extra info.
    This might be especially true if the colours have been changed (eg
    colour balancing) between opening the Adobe RGB image and saving as a
    ProPhoto RGB image.

    It may not happen in real life, try it and see.
    dj_nme, Sep 14, 2005
  14. Russell

    John Bean Guest

    I've looked at the models and I fail to see any significant
    clipping of ProPhoto that doesn't occur with Adobe RGB, that
    was my point.
    Not so. The wider space can be mapped into the smaller space
    such that the colours don't simply clip, but are
    progressively moved to fit. This allows subtle tone
    variations to still be visible at the expense of absolute
    colour accuracy.

    If using a raw file as a source ProPhoto retains far more of
    the colour the camera delivers than a smaller space can
    hold, and it's far better to retain as much information for
    as long as possible in the subsequent processing, rather
    than choosing a small colour space right at the beginning.
    John Bean, Sep 14, 2005
  15. Russell

    John Bean Guest

    Of course that's what I was assuming ;-)
    You need to do more research. I use Photoshop and Adobe
    Camera Raw (ACR), and all my raw files are converted to
    16-bit ProPhoto RGB by ACR as they are opened in Photoshop.
    John Bean, Sep 14, 2005
  16. Posterization will only occur if the printer does not support the gamut of
    the color space being utilized, and therefore has to convert to a more
    narrow gamut, using its more limited choice of color to fill the holes where
    color outside its gamut exists. Most inkjet printers are limited to the sRGB
    space, a smaller gamut than aRGB's. You could can get a degree of
    posturization during the conversion from aRGB to the printer's sRGB ability.
    The concern is far more relivant to an average home user who has a consumer
    level inkjet printer than it would be to commercial printers (print press
    businesses) because they purchase the commercial equipment that supports
    wider gamuts.

    Take care,
    Linda Nieuwenstein, Sep 14, 2005
  17. Russell

    Hecate Guest

    Well, you do what you need to do, and I'll do what I need to do as you
    obviously think that wider is better. Maybe you'd like to try WideRGB?


    Hecate - The Real One

    Fashion: Buying things you don't need, with money
    you don't have, to impress people you don't like...
    Hecate, Sep 15, 2005
  18. Russell

    dj_nme Guest

    Then you assuming the use of a camera that doesn't (yet) exist.
    If you've got a camera or scanner that can natively record in prophoto,
    it can't be a Canon, Contax, Sony, Nikon, Sigma, Pentax or Fuji because
    none of them make a camnera that can record a prophoto colour space
    image to it's memory card.
    It isn't your camera that makes the prophoto clour image, it is your
    software on your computer (from a raw image file that your camera _can_
    dj_nme, Sep 15, 2005
  19. Russell

    Colin D Guest

    As I understand it all, your post-processing can *reduce* the gamut from
    the original, but expanding to a wider gamut from a narrower one is
    pointless. The original gamut is determined by the filter response
    curves in the camera, and if the camera can produce aRGB files, you can
    reduce them to sRGB, but expanding to prophotoRGB is pointless, since
    the colors that gamut can encompass do not exist in the original file.

    Colin D.
    Colin D, Sep 15, 2005
  20. Russell

    John Bean Guest

    Raw files are unprocessed in the camera, that's why they're

    Only later when the raw files are converted to RGB is a
    colour space chosen, so there's no "expansion" at all by
    using ProPhoto, just less clipping than would occur if using
    either of the two much smaller spaces.
    John Bean, Sep 15, 2005
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