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An introduction to Colour Management.

Discussion in 'Image Processing' started by flash, Jul 30, 2012.

  1. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    • Like Like x 18
  2. sokar

    sokar Mu-43 Veteran

    392
    Nov 30, 2011
    Thanks Gordon for the great read. I have definitely been one to neglect this until now. I have tried to calibrate a monitor by eye using web page guides and had essentially given up.
     
  3. Livnius

    Livnius Super Moderator

    Jul 7, 2011
    Melbourne. Australia
    Joe
    You're a champ Gordon....really appreciate the effort. That link has gone straight into my favourites. Some important reading (and eventual questions) to be done.

    Thanks again.

    Joe.
     
  4. Bhupinder2002

    Bhupinder2002 Mu-43 Hall of Famer

    Thanks Gordon and its really helpful . Many people ignore this very important aspect .
    Cheers
    Bhupinder
     
  5. phrenic

    phrenic Mu-43 All-Pro

    Sep 13, 2010
    Thanks for the write-up. Favourited! Great for those with no clue about color management like myself.

    Sent from my iPad using Mu-43 App
     
  6. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    Gordon, do you have the color space set at sRGB or AdobeRGB in your GH2 camera? Why?

    I use Lightroom to process photos, which would make me think that maybe AdobeRGB is the right choice, but then again I mostly output to web or print services that use sRGB, so I'm torn!
     
  7. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    All my cameras are set to raw plus jpeg-fine and sRGB. The raw file ignores the colour space completely, of course. With a raw file colour space isn't permanantly assigned until you "cook" the data into a file (jpeg, TIFF etc...) so if you only shoot raw it doesn't matter with regard to the final image or Lightroom. Lightroom only uses Melissa RGB although version 4 has soft proofing (finally!). The factory software will default to whatever you set in camera, but you can change this with raw files.

    I shoot the attached jpeg in sRGB because I'm most likely to use that when I need a Facebook shot or to quickly email out a shot. Basically, like you, most of my jpegs get used on the web. Or I'll stick it on the iPad for the family to view if we're travelling. Last week I did a corporate shoot and needed to provide a slideshow at diner. sRGB is the obvious choice for this use. For my work I ALWAYS send sRGB files unless specifically asked. If they do want higher bit depth then I'll send a nice fat TIFF.

    Do remember though that what ever you set , even in raw capture affects what the display (EVF and LCD) show as they use the embedded jpeg. So does the histogram. If you use the histogram for capture then set the colour space to the likely output space. I never worried about this but some do.

    Gordon
     
    • Like Like x 1
  8. tubedriver

    tubedriver Mu-43 Regular

    138
    Mar 30, 2012
    Perth, Western Australia
    Shaun
    Hi Gordon,

    Thank you so much for taking the time to write this excellent piece. I am sure many other will really appreciate it as well.
     
  9. RobWatson

    RobWatson Mu-43 Hall of Famer

    How does having all my devices calibrated help some one out in cyber space view my images when their gear in not calibrated?
     
  10. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    It doesn't and it is their loss. But on the same token, it will match all the other color managed work and will not stick out when viewed because it will appear equally as bad.
     
  11. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    Great read, Gordon.

    Just to add to the conversation, color management will not make your colors look good. If you have really bad color, it will make sure the color stays bad and be that particular bad color, not simply a random bad color.

    THE two best practices you can do is profile your monitor and make sure an ICC profile is attached to your file. The monitor profiles let you get a good idea at what your file looks like and the ICC profile defines those colors.

    Gordon covered the idea of the gamut, but if a pixel has has R, G, and B values, does that not tell you what color it is? No. While RGB is a coordinate, it dos not describe a particular color. Only when the color space has been defined, like sRGB or Adobe RGB, then the values describe a color. Without a known color space, the only way of getting accurate color is by guessing.

    You can see what this means in Photoshop. Open an image and open the histogram display. Then go into the edit menu and choose the "assign profile" option and select the ProPhotoRGB space. What happens to the image is extreme--color, saturation, and contrast shift dramatically. Undo and redo the change and look at the histogram. The histogram does not change. What you have done is simple taken the RGB values and moved them from one space to another without changing them. The is a color management system not working.

    Now go back to your original image and change the profile by using the "convert to profile" option in the edit menu. The color does not shift in the image. But look at the histogram. The histogram changes because the RGB values are recalculated to preserve the color. That is color management at work.

    An image exists in a particular space. The output devices have their own space. Color management understands the differences and does the calculation in order to preserve the colors as they move from one space to another.
     
    • Like Like x 2
  12. Conrad

    Conrad Mu-43 Veteran

    One addition concerning Windows, since you apparently work in an Apple environment.

    Windows (XP/Vista/7) does not support wide gamut displays properly (wider than sRGB like Eizo ColorEdge). You can store monitor profiles, but Windows itself does not use them. Photoshop uses them, Windows Photo Viewer uses them, and a whole other series of individual programs as well, but Windows itself is internally "hard wired" sRGB. As a result, colors will look too saturated, except when using a color managed program.

    An interesting situation is posed by web browsers. There is only one browser that reads embedded profiles properly AND uses the monitor calibration for display: Firefox (and only after switching a "hidden" config parameter). For more information see: WEB BROWSER COLOR MANAGEMENT Tutorial - Test Page FireFox Safari Chrome Internet Explorer IE 10- FILES have embedded ICC profiles Photoshop ColorManagement
     
    • Like Like x 2
  13. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    Actually I'm ambidextrous. I use both. I actually started my colour management journey on Windows 2000.

    XP was hugely frustrating because not only were the applications not colour managed (is, paint, etc), but the OS would just dump a monitor profile at random times. Frustrating. Vista and 7 have made large and significant changes to their colour management integration. Since the release of ie9 there have been less and less issues with Windows colour management. Windows 7 utilizes colour management throughout the OS. So using the OS to preview an image doesn't have any problems, for example. I use a Windows 7 machine as my print server and it has no issues with the 100% aRGB screen it runs.

    Personally I prefer Safari if I'm doing colour managed work as it has colour management turned on by default. Firefox is fine but 90% of users haven't enabled the colour management. It should be on by default.

    Gordon
     
    • Like Like x 1
  14. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    It's not about them. It's about you. And its about consistency, not accuracy. When you process images you want to know that you're actually getting a consistent look. In an uncalibrated environment they may look the same on your screen but not on others as things might be happening in the background that you can't see.

    Plus you'll be able to send work out to other colour managed environments (printers, stock libraries etc) and know that they're seeing what you are. You can't worry too much about the ones who don't colour manage. They're not fussy enough to notice anyway.

    Gordon
     
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  15. Chrisnmn

    Chrisnmn Mu-43 All-Pro

    Apr 26, 2012
    Auckland, New Zealand
    Chris
    I personally use Adobe 98 on my cameras and shoot raw. NEVER shoot from sRGB since is a more compressed or should I say not as wide as the Adobe 1998 color profile. Some cameras can also shoot in ProPhoto RGB (which was the case of my now gone Canon 5DMKII) which has an even wider color spectrum. Color profiles are pretty much like "sensors" to the image, the "wider" the color profile, more information, and more can be tweaked or expected when printed from an image.

    I only use sRGB when uploading to Tumblr or Flickr and such since is the most common Color profile on the web and in most computers so everyone can see more or less my images as I want them to look. Noted how i said more or less?, its basically because in color management you will never get the same look across computers unless they are all calibrated like yours, which chances are 98% not to be.

    It is important to understand this not only applies for Photography, is important for anyone related to graphics-visuals done in a computer environment, TV, Design, Retouching, Photo, you name it...

    Sounds like a hard thing to do, but is not, after reading and trying things out for a bit.
    Also i strongly recommend everyone to get one of these guys Spyder4PRO - Datacolor Imaging Solutions - Datacolor Imaging Solutions is cheaper than a "P14" to put in perspective ehehehe...and can totally make the difference while editing and printing your images....

    and remember guys, dont expect other people to have calibrated monitors, only make sure, yours is calibrated for all your PP and when sharing, dont sweat it, just make a sRGB copy of the photo and there you go. everyone will see it like you want them to see it.

    I had a teacher that once explained to me color profiles quite simple:

    "color profiles are sunglasses, when you tell someone, hey check my photo, but dont give them the sunglasses they wont see the same thing as you."

    also heres some more reading if you want to also understand bit more about ProPhoto RGB done by Kodak. Understanding ProPhoto RGB

    so its all this worth?. yes it is, even though most printers will ask you for an 8bit Adobe98 TIFF for printing purposes. If you want the printer to print the exact same photo as you see it in your screen, you gotta send the color profile you used with your photos in order for them to match the colors.
     
  16. Promit

    Promit Mu-43 All-Pro

    Jun 6, 2011
    Baltimore, MD
    Promit Roy
    AdobeRGB is probably not a good idea for JPEGs, and I believe the setting does not affect raw capture.
     
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  17. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    If you really care about you color workflow, you would only shoot jpg for ease of posting on the net, but would shoot RAW for important work. Like everything else, the color space of the RAW image can be specified when opened. That allows great flexibility.
     
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  18. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    I agree.

    sRGB in a smaller space can lead to smoother transitions between tones. I know of a few people who deliberately shoot portraits in sRGB deliberately in order to avoid the more saturated colours in aRGB and to smooth out tonal graduations.

    Gordon
     
  19. Promit

    Promit Mu-43 All-Pro

    Jun 6, 2011
    Baltimore, MD
    Promit Roy
    I actually read somewhere that in very color critical cases (skin tones for magazines etc), 8 bits stretched over AdobeRGB gets so imprecise that it's impossible to get correct tones because the deltaE pushes past 4 in the best case.
     
  20. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    I am not sure that works. While sRGB has a smaller gamut than Adobe RGB is designed for monitors and I have found that it saturates primary colors very well. I would say if your friends are having a saturation problem, it is coming from the shooting or processing than the color space/CM (if the CM is correct, flat subjects will not be saturated regardless of the color space) and this would also be in controlled lighting in the studio. A common cause of saturation is contrast adjustment--folks love to pump contrast and think it does not impact saturation, but it really does and quite significantly. Contrast to skin tones can make keeping the skin looking natural very difficult. Color space/CM is really not a control over saturation.

    The gamut of Adobe RGB is not that large where you should notice problem with tonal separation or banding. The only color space you really need to worry about in that regard is ProPhotoRGB which needs to be kept 16-bit or you are going to run into really problems--I would not really recommend ProPhoto except for under exceptional conditions.
     
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