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LR ProPhotoRGB Gamma 1.8 and monitor calibration

Discussion in 'Lightroom General Discussion (ARCHIVE)' started by Braders, May 11, 2008.

  1. Braders

    Braders Active Member

    Oct 23, 2007
    Perth, Australia

    After learning that LR ProPhotoRGB is a Grey1.8 gamma working space, i wonder....

    Does this have any relation/effect/consequense on how i calibrate my monitor?

    Specifically, when i use my i1match 3, i set the gamma to 2.2. Should i be setting it to 1.8?

    Or, am i on mars, and they totally unrelated?
  2. Sean McCormack

    Sean McCormack Lightroom Guru Lightroom Guru

    Oct 7, 2007
    Where did you learn that? that doesn't sound right.

    Use 2.2...

    From a recent online conversation via email list:

    Lightroom (and Camera Raw) uses a "working space" (meaning the processing
    color space) of Pro Photo chomaticities (colors) and a linear gamma (1.'

    Martin is correct to call LR's working space as linear, but (and this is
    where it gets confusing), "Melissa RGB" (the color space coined by Mark
    Hamburg) isn't the processing space of LR/CR but the display space in

    Melissa RGB does indeed have the Pro Photo chomaticities but the gamma is
    actually that of sRGB and the ONLY place where Melissa RGB is used is for
    the Develop histogram and the color readouts.

    There was a podcast with Mark Hamburg, Bruce Fraser, Zalman Stern and Thomas
    Knoll where the whole "Melissa RGB" color space was discussed (I was there)
    but because of the presence of alcohol (a Bourbon as I remember) the whole
    thing got pretty confusing.

    So, Lightroom's internal processing space is ProPhoto RGB in a linear gamma
    (1.') but Melissa RGB is ProPhoto RGB with an sRGB tone curve. Also note
    that the sRGB tone curve is not a simple gamma curve but is a tweaked curve
    based on gamma 2.2 but with the toe adjusted.

    And to answer the original question, no...you really REALLY don't want to go
    down this rabbit hole at all. Just export out of Lightroom in the RGB space
    you want to work in with Photoshop. Your choice is sRGB, Adobe RGB and
    ProPhoto RGB.

    Jeff Schewe
  3. Victoria Bampton

    Victoria Bampton Lightroom Queen / Owner Staff Member Administrator Moderator Lightroom Guru

    Sep 29, 2007
    Southampton, UK
    Lightroom Experience:
    Power User
    Primary OS:
    Mac 10.12.x Sierra
    Lightroom Version:
    6.10 / CC 2015.10
    Lightroom License:
    CC Subscription
    Great info Sean.
  4. Braders

    Braders Active Member

    Oct 23, 2007
    Perth, Australia
    Luminous Landscape - Jeff Schewe "Camera to Print".

    ProphotoRGB - Gamma 1.8
    sRGB AdobeRGB - Gamma 2.2

    Maybe i took the comment out of context, but i am sure thats what he said.
  5. Braders

    Braders Active Member

    Oct 23, 2007
    Perth, Australia

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