sRGB, Adobe RGB (1998), & ProPhoto RGB

Discussion in 'Beyond the Basics' started by KmH, Jan 9, 2016.

  1. KmH

    KmH In memoriam Supporting Member

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    I find myself continually having offline photography discussions with photographers who should, but do not understand that digital cameras are able to record way more colors than the sRGB or Adobe RGB (1998) color spaces have in their color gamuts.

    But before I go on I want to make one one thing clear.
    The sRGB and Adobe RGB settings on your camera DO NOT APPLY TO Raw FILES. The sRGB and Adobe RGB settings on your camera only apply to TIFF and JPEG files made in your camera.

    Adobe provides a color space that lets you take full advantage of all the colors your digital camera can capture - ProPhoto RGB.

    If you make image file types in your camera that does use the sRGB or Adobe RGB settings you lose all the colors outside those 2 color space gamuts The colors lost are saturated yellows and cyans.

    Some History

    The sRGB color space was developed in 1996 by Microsoft and Hewlett-Packard.
    Michael Stokes spearheaded the development, first as an engineer for HP who then went to work for MS.
    sRGB was developed for displays, printers, and the Internet.
    It's likely the s stands for simple or standard. It has been suggested over the years that the s stands for s***, bit I doubt that.

    The Adobe RGB (1998) color space was kind of an accident and also involved a typographical error.

    In the late 1990's the second engineer hired to work on Photoshop - Mark Hamburg - was working on a new color management feature for Photoshop 5.
    The feature was to have 3 color spaces - an input color space, a working color space, and an output color space. Though it seemed a straight forward feature lots of people wrapping their mind around the need for having input, working, and output color spaces.
    So Mark started surfing the web to learn more about color spaces, and RGB color spaces in particular. Mark ran across a working color space "proposed" by the Society of Motion Picture and Television Engineers (SMPTE) for use editing HD video. The color space had the tentative name - SMPTE - 240M. Using the published RGB color coordinates and gamma information Mark made an ICC profile of the color space and that working color space shipped with Photoshop 5 as the STMPE-240M color space. (Released May 1998. Current Photoshop CC 2015.1 is Photoshop 16.1)
    The SMPTE notified Adobe in 1998 regarding typos that gave the wrong specifications to 2 of the RGB colors. The SMPTE corrected the typos in their version of the color space. Photoshop decided even with the typos the color space was useful, left their version of the color space as it was, and renamed it Adobe RGB (1998) in the Photoshop 5.0.1
    By the way. Mark Hamburg was the guy that lead the development of Photoshop Lightroom.

    Kodak developed an editing color space called the Reference Output Medium Metric RGB (ROMM RGB) but soon changed that mouthful to the more friendly name - ProPhotoRGB.
    Thomas Knoll, the father of Photoshop and Adobe, was impressed with ProPhoto RGB when he realized it could be an editing color space large enough to accommodate all the color information a digital camera could record. That would be very useful in the Adobe Camera Raw (ACR) Thomas was then developing. Thomas used the chromaticity values of ProPhoto RGB,but used a linear gamma of 1.0, instead of the 1.8 gamma Kodak used, so ACR would preserve the tone mapping it does of a Raw file. (Note: ACR was first available with Photoshop 7.0.1, August 2002.)
    (Note #2: About 13% of the ProPhoto RGB color space colors are not in the color spectrum visible to humans.)

    Summary

    To maximize your post production options - make Raw image files, not JPEGs or TIFFs.
    In ACR set the working color space to ProPhoto RGB.
    Lightroom's Develop Module is already set to Adobe's version of ProPhoto RGB (and is sometimes called Melissa RGB because of the 1.0 gamma Adobe uses.)
    Use ProPhoto RGB as your editing work space in Photoshop too. Note however that you want to use Photoshop's 16-bit capable editing tools first, and then finish with Photoshop's 8-bit only tools.
    (Note: For most practical purposes LR's Develop module and Camera Raw are the same, which is why we can go from LR directly to Photoshop for additional, and higher precision editing.)

    ProPhoto RGB is not on output color space.
    For output going to the Internet or multimedia devices change from ProPhoto RGB to the RGB Color (Image > Mode > RGB Color).

    When moving from LR to Photoshop for additional editing be sure your external editing options in LR are set to ProPhotoRGB.
    Non Adobe external editing applications won't play nice with the version of ProPhotoRGB ACR uses


     
    Last edited: Jan 10, 2016
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  2. Buckster

    Buckster In memoriam

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    Good info.

    You noted that there's no advantage to using ProPhoto RGB if output for internet display is the intent, since it'll just need to get converted to the smaller RGB gamut anyway.

    What about printing? Which printers take full advantage of the entire ProPhoto RGB gamut?
     
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  3. KmH

    KmH In memoriam Supporting Member

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    Most high end printing machines can print all of the visible colors in the ProPhoto RGB color space.

    If you have someone else that has a high end printer do your printing or outside publishing you would want to make sure they can honor your color management settings if you embed the ProPhotoRGB color space profile in the image file(s) to be printed.
    If that print service has color management settings that ignore embedded profiles, and many online print services don't want files sent to them that have embedded profiles, your prints may not look very nice.

    For prints, most of the consumer online print services do not use high end printers and want customers to upload files that are in the sRGB color space and that do not have an embedded color profile.
    Some online print services can/will print files in the somewhat broader Adobe RGB color space, and will print files that have the Adobe RGB color profile embedded in the file.
    Color space - Wikipedia, the free encyclopedia

    Like the color space issues above that many working photographers today should be but are not aware of, there are considerations for having high quality prints made that many working photographers are also not aware of, like embedding color profiles.

    Worse still, many working photographer's customers are not offered prints made by the photographer and instead are handed a disc of images for the customer to have prints made from.
    Few customers have any idea how to prepare a digital image file for printing.
     
  4. Buckster

    Buckster In memoriam

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    This is all really good info Keith, and very interesting indeed. Thanks for sharing it.

    When you say "most high end printing machines", are you talking about machines that reputable photo printing services would use, as opposed to consumer / home printing machines like the Canon and Epson models commonly found amongst us photographers? Or does it include the models we commonly have?

    Also, what would you recommend as the preferred output file format to send to a printer to ensure retention of the color space gamut after all editing is done and the image is print-ready? TIFF, maybe?
     
  5. Ysarex

    Ysarex Been spending a lot of time on here!

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    That one needs documentation.

    Joe
     
  6. KmH

    KmH In memoriam Supporting Member

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    High end printing machines have a lot more ink colors than consumer/home ink jet printers have. Like 12 or 14 ink colors and print heads.
    So that refers to ink jet printers, not chromogenic print machines that project the image file onto light sensitive paper.

    Joe,
    Real World Color Management - Bruce Fraser
    The Digital Print Page 71, Working-Space Profiles - Jeff Schewe
    Fine Art Printing for Photographers: Exhibition Quality Prints With ink Jet Printers by Uwe Steinmueller

    IIRC - Luminous Landscape online too .

    The specifications of high end ink jet printers, just be mindful the print media (paper) could be a limiting factor.
     
    Last edited: Jan 11, 2016
  7. Ysarex

    Ysarex Been spending a lot of time on here!

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    I'm familiar with high end inkjet printers -- I use them. I'm also familiar with Fraser and Schewe's books as well as Luminous Landscape online. Multi-ink high end printers are capable of printing colors outside the sRGB and even the Adobe RGB color spaces. But just because an Epson 4900 for example can print a yellow that is outside Adobe RGB does not mean it can print all of the colors of the Adobe RGB color space, yet alone the visible ProPhoto colors.

    So I'm calling this statement bogus: "Most high end printing machines can print all of the visible colors in the ProPhoto RGB color space." Let's see the documentation. If any printer can actually do that (yet alone most) I'm sure the manufacturer(s) have posted the news all over the Internet.

    Joe
     
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