Colour space setting impacts RAW?

Discussion in 'Digital Photography' started by Alfred Molon, May 28, 2007.

  1. Alfred Molon

    Alfred Molon Guest

    Somebody claimed that the colour space setting even impacts the RAW data
    on some cameras, because the gains of the amplifiers of the invidivual
    colour channels apparently are different under different colour space
    settings. Is this true and for which cameras does this hold ?
     
    Alfred Molon, May 28, 2007
    #1
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  2. Alfred Molon

    John Bean Guest

    Untrue.

    I think "somebody" is confusing this with white balance,
    which can on some cameras change the raw data for that very
    reason.

    My Pentax *istDS scales the channels according to WB before
    saving the raw data, but the newer K10D for example does
    not. It's of little consequence unless the camera WB is set
    wildly different from reality, in which case some channel
    clipping can occur prematurely.

    Probably the commonest example is tungsten light with the
    camera set to "shade", which easily clips the red channel
    unless you're very careful with the exposure.
     
    John Bean, May 28, 2007
    #2
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  3. Alfred Molon

    John Sheehy Guest

    I heard this for the Nikon D200 or the D2X, a while back, but I have never
    seen evidence of full WB in the RAW data. There are small changes in gain
    done on the integers after digitization, but they are not enough to come
    close to WB'ing the image, and I don't see any reason to think they have
    anything to do with the WB setting.

    Now, it may be possible for the Sigmas, since they may read the color
    channels separately and not have any issues with altering gain for every
    other pixel, as in a typical bayer camera, which reads alternating RGRGRGRG
    or GBGBGBGB. IIRC correctly, most Sigma RAW data I've seen, already has
    white as white. Most cameras have white as cyan-ish green in the RAW data
    when shot in "white" light, as the green filters pass more photons from a
    full, even spectrum, than blue or red (least).

    --
     
    John Sheehy, May 28, 2007
    #3
  4. Alfred Molon

    John Sheehy Guest

    Sorry, I need to finish my morning coffee before replying to posts!

    I thought I saw "white balance" in your original post, so that is what I
    replied to.

    I seriously doubt that any camera would alter the RAW data in any way for a
    color space. A camera's RAW has its own color space, and going to a color
    space is part of the conversion process, and nothing that could be done to
    the digitized data is going to aid in the final conversion.


    --
     
    John Sheehy, May 28, 2007
    #4
  5. Alfred Molon

    Jim Guest

    It is true that the white points of the various gamuts are not equal. This
    very slight difference may be visible if you compare the results of a RAW
    download to several different gamuts.

    Jim
     
    Jim, May 28, 2007
    #5
  6. Alfred Molon

    acl Guest

    The D200 (or, to be more precise, at least my D200) does not do
    anything to the raw data that changes with the WB setting.
     
    acl, May 28, 2007
    #6
  7. Alfred Molon

    Robert Coe Guest

    Somebody claimed that the colour space setting even impacts the RAW data
    : on some cameras, because the gains of the amplifiers of the invidivual
    : colour channels apparently are different under different colour space
    : settings. Is this true and for which cameras does this hold ?

    Depending on how expansive your notion of a color space setting is, I believe
    the Canon XTi qualifies.

    Bob
     
    Robert Coe, May 29, 2007
    #7
  8. Alfred Molon

    John Sheehy Guest

    There was a rumor when it came out that it did.
    --
     
    John Sheehy, May 29, 2007
    #8
  9. Alfred Molon

    John Sheehy Guest

    Howso?

    If you know of a way to get around it's low RAW exposure, that would be
    nice. When I get to it, I'll shoot a blank wall with sRGB set, and with
    aRGB set, and see if there are any differences.



    --
     
    John Sheehy, May 29, 2007
    #9
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