Strange Lightroom ProPhoto -> sRGB Conversion Problems

Discussion in 'Digital Darkroom' started by david_glick|1, Mar 26, 2008.

  1. Hi all,

    I'm hoping someone can help me with this because I've been searching and
    reading for over an hour and can't seem to get a handle on it. I am having some
    strange problems going from LR to sRGB JPGs for the web. In the past, I've
    never noticed a problem, but I'm now using a different monitor and a different
    camera (both around the same time) so one of those two things might be causing
    a new complication that I don't understand. In any case, the problem is that
    after tweaking a photo in LR to look just how I want it and exporting to an
    sRGB JPG from within LR, the exported JPG looks very different (and worse) then
    the LR equivalent. I've noticed this in several shots now. The JPG files seem
    to take on a reddish tint and appear darker.

    I know LR uses ProPhoto RGB as it's working space, and that this has a much
    wider gamut then sRGB. My understanding, though, was that when exporting to
    JPG, LR performs a perceptual color space conversion to try and maintain the
    image as much as possible. When I send the file straight to Photoshop for
    editing and perform the color space conversion there, the result is exactly
    what I would expect. My only conclusion so far is that there is a problem with
    the way LR converts from ProPhoto to sRGB color space (though I'm hoping I just
    don't understand something). I really don't want to hear "well just always
    convert in Photoshop" - that defeats the purpose of attempting to use a good
    all around converter/editor like LR.

    I've included a screen capture to show the difference. The image on the left is
    the converted JPG from LR, and the right is the LR develop module. Thanks for
    any help anyone can provide.
     
  2. Is your monitor calibrated? If not, it may be that your previous monitor jut happened to be closer to sRGB than your current one.
     
  3. What tool are you using to view the JPEG? Is it color-managed?
     
  4. My current monitor is not calibrated right now (though neither was the other one). The JPG viewer I've been using is the built-in Windows Image Viewer - it is not color managed, and uses the same API that most non-image-focused Windows applications (such as IE) would use.

    I am going to try and calibrate my monitor soon - but I still don't understand why the conversion straight from LR->JPG would be so different from the LR->Photoshop->JPG conversion...and why the latter is so much better (in the sense of being closer to the LR version when viewed).
     
  5. I would agree that whatever one you would use to convert to srgb...the photo should look the same on the same computer/monitor
    combo.
     
  6. Based on the screen shot of LR and Windows Image-Viewer, it certainly appears that the ProPhoto->screen conversion that LR is doing to show the image is different than the cumulative ProPhoto->sRGB and sRGB->screen conversion that LR and the Image-Viewer are doing.

    I believe the MS Image-Viewer is color-managed, but I'm not sure what it does when there's no monitor-profile. I generally use FireFox or IE when I want to make sure there's no color-management going on between the file and the screen.
     
  7. To further test, I opened the JPG from LR in IE (enough acronyms?) and it looks the same as it did in Windows Image Viewer (or at least very similar).
     
  8. Just for fun, I displayed the same image in the "Windows Picture and Fax Viewer" and FireFox 2.0.0.12. Visually the colors appear identical, and some spot color picks from the screen shot are pretty darn close.
    00OwJo-42537084.jpg
     
  9. >Just for fun, I displayed the same image in the "Windows Picture and Fax Viewer" and
    FireFox 2.0.0.12.

    Those applications are not ICC aware. The previews, even of sRGB may not match what you
    see in Lightroom or Photoshop, those being ICC aware applications (and previewing the
    numbers correctly).
     
  10. Okay - I think I've gotten to the bottom of it. I noticed in my monitor settings (from Windows) that my display device was using a custom ICC profile that must have been installed with the drivers. I manually added sRGB as my display profile and restarted. Low and behold, LR and it's sRGB output now look nearly identical. This suggests that LR must be interpreting its internal ProPhoto representation for display using the device ICC profile (as it should) somewhat differently then Photoshop does. So the problem (if there even was one - it was probably more my misunderstanding of how color management works) was more with LR displaying an editing view that wasn't what was expected then the output not matching the editing view (if that makes sense).
     
  11. >I manually added sRGB as my display profile and restarted. Low and behold, LR and it's
    sRGB output now look nearly identical.

    You didn't fix anything, you essentially now lied to Photoshop and other ICC aware
    applications such that they now show you the wrong previews just like all the other non ICC
    aware applications. Photoshop and other ICC aware applications need a profile that defines
    how your display behaves so it can produce the correct color appearance from the numbers.
    You just ripped that functionality from Photoshop, now everything matches (incorrectly).
     
  12. Andrew Rodney, "You didn't fix anything..."

    Well, yes he did.

    He doesn't have a calibration system (yet), so the problem was the incorrect profile that LR was using to (incorrectly) convert his ProPhoto colors to the monitor's space. Now he's installed the "best guess" profile so LR does as-close-as-it-can-to the right thing.
     
  13. People who don't calibrate their monitors have no right to complain about why images appear differently between applications. Andrew is right.
     
  14. For most of us David observations is a main issue. When we print our pics or just post them on the web, the space required is sRGB (not many popular labs apply colour management at least here) and in light room we are tweaking withouth knowing the final result that only will be visible when we convert to sRGB. In photoshop you can turn the proof colours to get an idea of how pics will look in sRGB but not in LR. As conclusion the perception of wider spaces in display is only interesting for people who prints using these spaces (or labs with colour management). On the other hand the final test is process one pic with the raw converter of your camera and with light room the difference is awesome. LR is far worst. Part of this effect I think is due to that LR displays (at least you have done David manual configuration of monitor) prophoto colours , which look greeninsh and ugly on our screens.
    That's how I see it I would like some expert input in order to make everything right but definitly is not lack of calibration what david sees.
     
  15. >Well, yes he did.

    Well no he didn't. I explained why. Now all ICC aware applications are as completely wrong
    about previewing the numbers. And if you think that his display's native behavior is sRGB,
    and thus, using sRGB as a display profile is getting him closer to correct, that's not the case
    either. There hasn't been an sRGB display behavior since about 1993 using a CRT with P22
    phosphors. The various applications all match in producing the wrong previews. That's not a
    fix.
     
  16. So what is the solution?? I am really concerned about this.
    How can we "see" the results produced by srgb output in LR?
    I agree it is not a fix, I thought you could as you said "get closer" because of the srgb nature of the screen. Any advice will be welcome!
     
  17. >How can we "see" the results produced by srgb output in LR?

    Just as you can see the results of sRGB in Photoshop or any other ICC aware application.

    There are two mechanisms going on here. First you have a pile of RGB numbers that are
    associated with a color space known as sRGB (we hope that association is correct). Next
    we have a display profile. Only with both pieces of info can an ICC aware application
    provide the correct preview of said numbers.

    Make a document in sRGB, Adobe RGB (1998) and ProPhoto RGB and paste R0/G255/B0 in
    each. The numbers are the same. The colors are NOT (they fall in different locations in the
    color space we call human vision). They will appear the same in ICC aware applications
    because of the architecture described above. Now open them in a non ICC aware
    application like nearly all web browsers. The colors do not appear the same (or correct) as
    they did in Photoshop or Lightroom (by all means, import all the documents into LR and
    view them).

    Now change the display profile and you'll see the colors preview differently in Photoshop
    (and LR). What is the correct preview of the numbers? That which uses a display profile
    that defines how that display is currently behaving.
     
  18. I understand I'm "lying" to my color managed programs about the capabilities of my monitor. That's fine with me given I can now edit and the output looks the same as my editing environment (isn't that really the point of color management anyway?).

    What I don't get is, how would color management help the situation. If I profile my monitor and use a correct ICC profile, would LR then output perceptual sRGB JPG files that closely match what I see on my screen? I suspect the answer is no, in which case, all I would have succeded in doing is making it impossible to proof my output in my editing environment - isn't that a bad thing?

    "People who don't calibrate their monitors have no right to complain about why images appear differently between applications." - tangential to this topic, the tone of this remark is disturbing to me. It suggests that everyone should know about color calibration and there is no excuse for not understanding it. It's a difficult and complex topic, and I'm guessing there are a lot of folks on here (myself included) who are just getting their toes wet and trying to understand how it all works...
     
  19. >I understand I'm "lying" to my color managed programs about the capabilities of my monitor. That's
    fine with me given I can now edit and the output looks the same as my editing environment (isn't that
    really the point of color management anyway?).

    NOT AT ALL! The point of color management is to give the RGB and CMYK numbers a meaning, to see
    the values correctly, to map values from one color space to the other (so you can map sRGB to
    MyPrinterRGB) and get the desired and expected color appearance.

    Go back prior to say 1998, Photoshop wasn't an ICC aware, color managed application. What you've
    done is make all versions of Photoshop since 5.0 now act like version 4.0 and earlier. That's NOT a
    good thing. So you lied to Photoshop and all other ICC aware applications and now they are all
    incorrect instead of only most of them being incorrect.

    With this logic, one could look at an image that appears too dark in Photoshop and instead of altering
    the RGB numbers to correct this, all you did was increase the luminance on your display so the image
    doesn't look as dark. How was that useful? It isn't. Nor is the process you applied to take the only one
    or two applications that had a chance of showing you the numbers (that's all computers understand
    anyway) correctly.

    >What I don't get is, how would color management help the situation. If I profile my monitor and use
    a correct ICC profile, would LR then output perceptual sRGB JPG files that closely match what I see on
    my screen?

    Forget sRGB and perceptual (we're not there yet...). What it does is show you the RGB numbers
    CORRECTLY and as everyone else would see them using an ICC aware application and a profiled
    display.
     
  20. Understood, I got it now. I will turn my monitor to pro photo again.
     
  21. >Understood, I got it now. I will turn my monitor to pro photo again.

    No, no no! Bad dog. You need to load a display profile (one that defines how that display is
    behaving). You never load an RGB working space here.
     
  22. "What it does is show you the RGB numbers CORRECTLY and as everyone else would see them using an ICC aware application and a profiled display" - got it... maybe :). So the crux of the issue is that when I've got the correct monitor profile installed, LR displays the wider color space correctly on my monitor which can also display that wider color space correctly, right? So if everything were profiled, when I print (for example), the print would look exactly like it did on my profiled monitor in my profile-aware application...

    So I'm still confused about outputting for the web, then. Why does the sRGB JPG output from LR look so different from the one output by Photoshop? How can I get the JPG output from LR to look like I think it should to the majority of viewers on the web?

    BTW - thank you everyone for the help! This is demystifying a lot for me, and hopefully the conversation is helpful to others as well.
     
  23. >o I'm still confused about outputting for the web, then. Why does the sRGB JPG output from
    LR look so different from the one output by Photoshop? How can I get the JPG output from LR
    to look like I think it should to the majority of viewers on the web?

    You need an ICC aware web browser. There's like two! Safari and the beta of FireFox for
    Windows. The web isn't color managed. That's the problem.
     
  24. It depends on what application you are viewing them with. If it is a color-managed one, you can use any color space and the results will be almost the same (clipping notwithstanding). It's when you have to deal with non-color managed applications that you have to be careful. Such applications are effectively working in the monitor's color space. Since the average monitor is close to sRGB, it is advised to convert your images to that in order for the omitted color space conversion (from sRGB to your monitor's actual color space) to be of minimal loss.

    When you are not working with color-managed applications you have to ABANDON the notion of exact matches. Just make sure your image looks acceptable in sRGB (by which I mean the clipping is acceptable), and move on.
     
  25. WOW , then still there is something i miss. I should not configure my display properties-advanced- colour management- "profoto" *.icc... ?
     
  26. >WOW , then still there is something i miss. I should not configure my display properties-
    advanced- colour management- "profoto" *.icc... ?

    Nope.
     
  27. Ok, after some more reading, I think I will have to calibrate my monitor proprly and create a profile. I am going to do it today with a friend's device to see how it works before buying one. Thanx again
     
  28. I calibrated my monitor using spyder2 express. I guess everyhting is ok now and I will work with colour management etc, but to be honest I do not see any difference :)
     

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