Photoshop and Huey: Double color correction?

Discussion in 'Photoshop' started by André Hänsel, Apr 14, 2008.

  1. Hi,

    I am using a Pantone Huey Pro for color correcting my monitor.
    Basically it does two things: It adds a profile to the monitor and the
    Software does a color correction (probably with the aid of the
    graphics card).

    Now Photoshop (CS2) does also use the monitor profile for color
    correction.

    Isn't the image over-corrected by applying it twice?

    Regards,
    André
     
    André Hänsel, Apr 14, 2008
    #1
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  2. André Hänsel

    Mike Russell Guest

    There is no double conversion. The Huey software calibrates the monitor,
    using the LUT in the video card, then creates a profile that describes the
    monitor. Then Photoshop uses the monitor profile oin the intended way: to
    convert color numbers for display.
     
    Mike Russell, Apr 14, 2008
    #2
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  3. André Hänsel

    Joel Guest

    I don't know what in your mind by doubling your confusion <bg> but this is
    how the whole thing works in general.

    - The Monitor Calibrator calculates the Monitor base on the lighting
    situation of your work station.

    - It then give the option to SAVE the Monitor Profile to computer (Windows
    for example as I am not Mac user to know anything about it), and tell
    Windows to use that specific Monitor Profile as the DEFALT.

    Yes, you can choose other monitor profile's if you wish, and Windows may
    have more/less profile files (probably depending on what you have installed
    on your system?)

    - Then just like all applications using Monitor Profile, Photoshop will use
    the DEFAULT (the one created and saved by Pantone Huey Pro) monitor profile
    as its default monitor profile.

    That's it! other than that I have no idea what the "TWO" and "TWICE" you
    have in
     
    Joel, Apr 14, 2008
    #3
  4. Hm, I'm not sure whether I understand. Let me wrap it in an example:
    In Photoshop I create a picture using a color, e.g. 10% red, 20%
    green, 30% blue. When I create a screenshot now and measure the color
    it is 19 R, 26 G, 35 B, because of the screen profile. When I now turn
    Huey color correction on, the color I see on the screen changes.
    So if this is the "correct" color, what is the color I saw when color
    correction was still off? Half corrected?
     
    André Hänsel, May 19, 2008
    #4
  5. André Hänsel

    Mike Russell Guest

    More than likely this is the interraction of the color profile, which
    Photoshop recognizes, and the video card's look up table (LUT), which
    directly changes the appearance of the RGB values.

    The exact explanation of your example is difficult to give for several
    reasons. YYou don't mention which software you are using to turn on the
    Huey color correction, and the interpretation of color values that are
    pasted into Photoshop depends on your profile mismatch settings in Color
    Setup. To preserve their appearance, screen shots should always be first
    assigned the display profile, then converted to your working color space.
     
    Mike Russell, May 19, 2008
    #5
  6. André Hänsel

    Roy G Guest

    Hm, I'm not sure whether I understand. Let me wrap it in an example:
    In Photoshop I create a picture using a color, e.g. 10% red, 20%
    green, 30% blue. When I create a screenshot now and measure the color
    it is 19 R, 26 G, 35 B, because of the screen profile. When I now turn
    Huey color correction on, the color I see on the screen changes.
    So if this is the "correct" color, what is the color I saw when color
    correction was still off? Half corrected?

    Hi

    If the Curvmeister says, then it is a certainty that he is correct.

    However, it could be that you are getting double correction, but only if you
    have left Adobe Gamma in your start-up folder. Adobe Gamma needs to be
    disabled if any other Calibration and Profiling system is installed.

    If you are in doubt about the way the Huey works, then you should be
    studying up on its insructions.

    Roy G
     
    Roy G, May 19, 2008
    #6
  7. To turn on the Huey color correction I use the Huey Software where I
    can switch from "Uncorrected" to "Corrected" which changes the
    appearance of colors immediately.

    Indeed when I take a screenshot of a picture that is in the color
    profile of my monitor (and not sRGB as before) the measured colors are
    the same, regardless of what color profile the image has that I paste
    into.
    Nevertheless could you explain what happens when I screenshot an sRGB
    image and leave Huey color correction turned off? By the way, when I
    remove the screen profile in system control and then screenshot an
    sRGB image I have consistent (but probably visibly wrong) colors.
     
    André Hänsel, May 19, 2008
    #7
  8. André Hänsel

    Mike Russell Guest

    On Mon, 19 May 2008 08:20:12 -0700 (PDT), André Hänsel wrote:

    [re monitor correction]
    If it works the same as the i1, this is changing the video card's lookup
    table (LUT) that was created by the Huey, but leaving the system display
    profile in place. Since the video LUT modifies the hardware settings, it
    is like a high tide raising all boats equally, changing the colors
    displayed by all apps, whether they are color aware or not.
    Photoshop copies the RGB values directly from the clipboard into the image.
    This will change the color appearance because Photoshop now believes that
    these RGB values belong to the image's working space defined by the image's
    working color profile, and uses the display profile to convert those colors
    from the image's color space to the display space, defined by the display
    profile.
    Photoshop converts your sRGB colors to display space. When you do the
    screenshot, you copy display space RGB values to the clipboard. Pasting
    them back into the sRGB image will put these converted color values back
    into the sRGB image space, and they will probably appear slightly different
    at that point.

    Since the Huey LUT is missing, this will alter the display appearance only.
    It does not change the RGB numbers.
    Photoshop uses a default screen space of sRGB if none is specified in the
    display properties. SRGB was designed to match the average monitor, so
    it's not surprising that it matches your display fairly well.

    Other thigs that color wonks might find interesting:

    In the advanced section of Color Settings, there are several options for
    dealing with profile mismatches. For opening an image file, there is a
    profile mismatch option to "Ask when Opening for images with both
    mismatched profiles missing profiles. There is an option for displaying a
    warning when a pasted image is tagged with a different profile, but the
    missing profile option is not available for pasting. This means that it is
    not possible to get a warning when pasting an image from a screenshot - the
    pixel values are silently assigned whatever your working profile is.

    It is easier to see how things work if you use a more extreme profile, such
    as Wide Gamut RGB or ProPhoto RGB. The increase in saturation with these
    profiles is so obvious that you will see whether colors are being changed,
    and whether they are being displayed correctly or not. The numbers also
    change more with these profiles. You can create your own pseudo profiles
    with various gamma values, and see if you can predict things like whether
    pasting a middle gray from a 1.0 gamma image to a 2.3 gamma image will make
    the image darker or lighter.

    You mentioned the notion of "accurate colors". I've posted another thread
    on the topic of "calibrationism vs by the numbers" that you may find
    interesting.
     
    Mike Russell, May 20, 2008
    #8
  9. This is a very good explanation of what happens when I take the
    screenshot, thanks.
    I'm not sure if I understood this, because my original question
    remains, but rephrased:
    When I open an image that is in sRGB (or even a more extreme profile)
    Photoshop tries to find similar colors in my display's profile to
    achieve that I see the image as genuine as possible, correct?
    So when I now turn on the Huey color correction, I void Photoshop's
    effort.

    Or does the Huey color correction serve the purpose of "correcting"
    color unaware applications and the Huey-created display profile
    describes the already corrected display so that color aware
    applications can target the RGB values to this color space?
    (Which answers my question whether the image in Photshop is "half
    corrected" when Huey is off with "yes".)
    Well, I predict that it will be darker, because when I paste pixel
    color values from the gamma 1 ("not gamma compressed" so to speak) to
    the gamma 2.3 image, the system will think they were gamma compressed
    (lightened) by 2.3 in the first place, so it will darken them before
    output.
    Yes, basically you're right but I hoped, with the aid of the Huey I
    could estimate better what I'll get from the lab by looking on my
    screen.
     
    André Hänsel, May 21, 2008
    #9
  10. André Hänsel

    Mike Russell Guest

    On Tue, 20 May 2008 19:15:20 -0700 (PDT), André Hänsel wrote:

    ....
    Yes, when you turn the LUT on and off, the appearance of the image changes,
    but not the screen grab numbers.
    You got it. The Huey LUT tunes in an appropriate gamma and color temp,
    based on what you specified. This is not a complete specification of the
    monitor appearance. The profile adds the finishing touches, and includes
    things like the purity of the monitor's red, green, and blue.

    ....
    [re pasting gamma 1 colors into a gamma 2.2 image]
    Easy to verify. Here's another brain twister: if you assign Wide Gamut RGB
    as your system's display profile, do the colors get more or less intense?

    [re accurate colors]
    This is probably the case. Screen calibrators are relatively inexpensive
    now, and work reasonably well. It also works to put a representative image
    on your screen, and adjust the controls to make it look right.
     
    Mike Russell, May 21, 2008
    #10
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