Digital Rebel and Adobe RGB

Discussion in 'Digital Photography' started by Darryl Shpak, Mar 1, 2006.

  1. Darryl Shpak

    Darryl Shpak Guest

    Hi,

    After being unhappy with the colour balance in most of my images (both
    on screen and in print), I've started to pay more attention to colour
    management in my workflow. I've purchased a Monaco Optix XR to
    calibrate my LCD monitor, and it's already made a world of difference.
    Naturally, as part of all this, I've started to pay attention to colour
    spaces.

    I do all my shooting with a Digital Rebel (the 300D). I don't much care
    for the extra saturation and contrast provided by the Parameter 1
    settings, and lately I've been shooting with the camera set to Adobe
    RGB. (Note: I do some shooting in JPG, some in RAW, depending on the
    circumstances. Everything I'm talking about here is referring to JPGs.)
    After I download the images (using ZoomBrowser), I open them in
    Photoshop, which then tells me that they do not have an embedded colour
    profile.

    This surprises me -- I would have expected that, with the camera set to
    Adobe RGB, it would record that within the JPG.

    Photoshop then allows me to select a profile to assign to the image.
    There are at least three I can find that make some sort of logical
    sense. First, I can pick "Adobe RGB". My gut tells me this is correct.
    Alternately, I could pick "sRGB", since I suppose it's possible that
    the camera does everything in sRGB, and that the "Adobe RGB" setting
    doesn't do what I think it does. Finally, I could choose "Canon EOS
    300D (Generic)", which makes a lot of sense too, since, y'know, that's
    the camera I have.

    Of course, all three of these settings give colours that look
    plausible. Some are more saturated than others, some have a bit of a
    different colour cast, but none of them are wild enough to be obviously
    "wrong". Chances are, I'm going to play with contrast and saturation a
    bit anyway.

    So, my questions (it was only a matter of time before I got to the
    point) are: Why doesn't the JPG have a profile embedded? And which
    profile should I assign to get the "best" results?

    My guesses are: No profile is assigned because the camera just doesn't
    bother (which is a real pain, since I have some images shot with Adobe
    RGB and others without, and now I don't know which are which), and that
    I should assign Adobe RGB if that's how the camera was set, and sRGB if
    I was shooting with Parameter 1.

    Can anyone verify this, or give me better advice?

    - Darryl
     
    Darryl Shpak, Mar 1, 2006
    #1
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  2. Darryl Shpak

    bmoag Guest

    To make it simple:
    You cannot assign AdobeRGB in the camera to jpegs.
    Make AdobeRGB the default color space in Photoshop.
    Set Photoshop up to ask you to confirm that you want to convert the incoming
    jpeg image to AdobeRGB. This is a bigger color space than sRGB (which is
    what your jpeg image is anyway) so you do not lose any color information.
    RAW images should be shot and manipulated in AdobeRGB.
    You can do what you want once you understand how color managment works but
    at the beginning color management works best if you follow strict protocols
    with regard to maintaining the same color space for processing all images.
    You should shoot RAW exclusively if you are interested in optimizing your
    images. To convince yourself shoot some tests of the same
    multihued/multitoned object in both jpeg and RAW and compare the results in
    Photoshop.
    As you have seen learning to use color management, as well as the infinite
    tools of Photoshop tremendously improves the quality of your pictures.
    Depending on how you implement color management and how your printer driver
    works you will have to convert your image to the printer/paper color space
    just prior to printing.
     
    bmoag, Mar 1, 2006
    #2
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  3. Darryl Shpak

    Bill Hilton Guest

    Darryl asks ...
    If you want more control over these issues then shoot RAW mode and when
    you convert use AdobeRGB (or ProPhoto or sRGB) ... jpegs are fine if
    you have the right white balance etc set up but you're letting the
    camera make a lot of the decisions for you, whereas if you go to the
    extra hassle of shooting RAW you have much more flexibility.
     
    Bill Hilton, Mar 1, 2006
    #3
  4. Darryl Shpak

    Darryl Shpak Guest

    Yes, I understand that. Like I said, I shoot RAW sometimes and JPG
    others. When I'm shooting "seriously", I shoot in RAW. I have no
    problems with colour management then. However, if I'm shooting casual
    snapshots, I like to shoot in JPG. If I'm shooting a 6-year-old
    cousin's birthday party, I want to shoot a lot of pictures without
    worrying about (a) space on my CF cards, (b) space on my hard drive
    (even with 300+ GB, shooting a gig of pictures at a time fills things
    up fast), and (c) processing the suckers after the fact. These are not
    serious photos that I'm trying to eke every ounce of quality out of.

    So from that perspective, it really doesn't matter too much if the
    wrong profile gets applied. But I'd still like to get the best results
    possible from this "lazy" workflow. The particular facet I'm looking at
    now is: When I set "Adobe RGB" in my camera, what should I be doing
    with the images that come out of my camera? Should I assume they're
    untagged Adobe RGB, and assign the Adobe RGB profile (with no
    conversion)? Or should I assume they're sRGB, and assign an sRGB
    profile (or convert them to Adobe RGB)?

    Actually, I'm leaning towards switching to Parameter 2 for my JPGs,
    shooting them in sRGB, and reserving Adobe RGB for my RAWs. After all,
    those snapshots are not going to see a lot of processing, and will be
    either viewed onscreen or printed at my local lab (which has an sRGB
    printer), so it may be that trying to add the Adobe RGB colourspace
    into that workflow is just a bad idea.

    - Darryl
     
    Darryl Shpak, Mar 1, 2006
    #4
  5. Darryl Shpak

    Ed Ruf Guest

    I believe this is the correct thing to do. They are in aRGB, but PS
    doesn't understand this.
    ________________________________________________________
    Ed Ruf Lifetime AMA# 344007 ()
    http://EdwardGRuf.com
     
    Ed Ruf, Mar 1, 2006
    #5
  6. Darryl Shpak

    crane763 Guest


    Can you please explain this above statement in a
    little more detail.

    I have followed the original poster's inquiry and the responses.

    But I don't quite understand why "You cannot assign Adobe
    RGB in the camera to jpegs"

    I have been wrestling with the same issue:
    I shoot jpg quick snapshots with my Olympus C-7000.
    The EXIF files show an sRGB tag associated with the
    image files. When I open a "tagged" image file in PS7
    or PS CS the software tells me it is an untagged file,
    and asks what do I want to do.

    So please, what is going on here.

    Thanks, Larry
     
    crane763, Mar 2, 2006
    #6
  7. Darryl Shpak

    kctan Guest

    I used a 10D before and the profile chosen is tagged. Something is missing
    in yours. You mentioned that camera does everything in sRGB space is not
    true. Every camera has its own color space or to be precise, its color
    gamut. This color gamut is a color reproduction produced interactively by
    the lens used, the light capturing sensors, the color filter array and the
    built-in interpolation program. Imagine the same roll of analog slide film
    taken with 2 different cameras don't produce colors alike too. Digital
    colors use 0 to 255 to represent its color tones. Therefore the same numbers
    that represent the colors of a scene taken by 2 different cameras are not
    identical. So color management came into
    the picture. The concept is everyone should see the colors as consistently
    as possible with the help of profiles to map the colors to the standardized
    ones.
    No colors improvement here. It is the image adjustments that improve
    the colors. That means if a picture is yellowish, everybody should see the
    same color bias and we use color adjustment to correct it. Display devices
    like monitors need to be calibrated and
    color profiles to map the colors to look alike. Output devices too
    have different color reproduction power (Gamut) like the input devices. sRGB
    profile is for the less colors power
    ones and aRGB for the wider ones and you choose them appropriately to use.
    Wider color space
    profile tagged produces more saturated colors but the overall color tones
    should be the same as long as you preserve the embedded profile in your
    chosen working color space.
    There is no tagged profile for RAW file but you
    assign one when you develop it into an image file like Tiff or Jpeg. No need
    to worry too much about what tagged profile your image has. As long as your
    monitor
    is calibrated properly, use the profile that maps to the color you favour
    best by visual comparison.
    Remember that choosing sRGB or aRGB is depended on the output devices colors
    reproduction capability.
    Color management system needs several profiles to interact and these are
    input profile, display profile,
    working space profile and output profile if you do printing.
     
    kctan, Mar 2, 2006
    #7
  8. Darryl Shpak

    Darryl Shpak Guest

    In my case, I think I've found the answer bo actually looking at the
    camera manual. (It's a radical approach, I know.)

    Section 3, Page 55, "Setting the Processing Parameter", in the
    description of the Adobe RGB setting, has the footnote: "The ICC
    profile is not appended. To convert the profile, you must set Adobe
    RGB."

    As best as I can make out, this is trying to tell me that the JPG is
    being recorded using the Adobe RGB colourspace, but the camera doesn't
    actually append the profile to the image, so when I open it in
    Photoshop, I should to assign the Adobe RGB file to it (without
    conversion).

    That said, kctan's advice makes a lot of sense: "As long as your
    monitor is calibrated properly, use the profile that maps to the color
    you favour
    best by visual comparison." Ultimately it's not a question of what's
    "right", but what looks the best.

    - Darryl
     
    Darryl Shpak, Mar 2, 2006
    #8
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