Correct White Balance Doesn't Mean Correct Color??

Discussion in 'Digital Photography' started by jim evans, Oct 21, 2005.

  1. jim evans

    jim evans Guest

    I read in google groups where someone posted this statement in this

    ". . white balance . . . is the first step but not quite the same
    thing [as correct color balance]. I.e., you can have poor color even
    if the white balance is set right. "

    Is this true? If so, why?

    jim evans, Oct 21, 2005
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  2. Just a simplistic guess... but if white balance was right and exposure
    was wrong, color would be wrong.
    Steve Cutchen, Oct 21, 2005
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  3. jim evans

    bmoag Guest

    Color is what you choose it to be and correct white balance may destroy the
    effect you are seeking:?
    bmoag, Oct 21, 2005
  4. jim evans

    GTO Guest

    GTO, Oct 21, 2005
  5. jim evans

    Mark² Guest

    The quotee was likely referring to *preset* WB settings, such as
    flourescent, tungsten, flash, etc.

    -Most environments have a *mixture* of light sources...and these sources
    create WB situations that do not fit neatly into the preset WB settings on
    the camera. A camera's WB settings assume that the SOLE source of light is
    that which it indicates (ALL flash, for example). When you shoot in these
    mixed lighting environments, it's almost NEVER going to be the perfect WB.
    This means that if you're picky, you'll still want to make at least minor

    In addition...If you're shooting a concert, and you want to preserve the
    blue light or red light of the stage, etc., you won't want the camera to try
    and compensate for the red light, etc.

    This is why no matter how "smart" camera tech becomes, it is STILL always up
    the photog to take control...if you want final say over what you capture.

    Custom white balance comes into play here, but even then, you can change the
    nature of light simply by pointing in a somewhat different direction within
    the same room, for example...where there may be a colored lampshade,
    fourescent kitchen light, etc. etc.

    Sitting here in my office, I have tungsten from a standard bulb...halogen
    from a desk lamp...and light from both my computer and TV screen. Then
    there's the hall lights casting rays into this room. As you can see...NO
    camera WB is going to accurately handle this setting. When I'm doing
    serious color work in Photoshop, I dim nearly all the lights in here, since
    it will even throw your human vision off (!).
    Mark², Oct 21, 2005
  6. Gary Hendricks, Oct 21, 2005
  7. jim evans

    jim evans Guest

    Thanks for the replies. But, either I didn't understand them or they
    don't address my question. I understand what white balancing is and
    why it's done.

    Perhaps I need to better define things.

    By "white balance" I mean including a gray card in the image and
    adjusting the color such that the card is gray -- R=G=B.

    By "correct color" I mean the color of any area or object in the image
    matches the color of the actual area or object photographed.

    Someone said "Color is what you choose it to be." I don't agree. A
    given red fire engine is a specific color of red. If you render it
    correctly the image will be the same red as that fire engine.

    Someone else said: "A camera's WB settings assume that the SOLE
    source of light is that which it indicates (ALL flash, for example).
    When you shoot in these mixed lighting environments, it's almost NEVER
    going to be the perfect WB. This means that if you're picky, you'll
    still want to make at least minor adjustments."

    This statement assumes the white balance is not correct. My question
    assumes the white balance is set correctly and asks if this statement
    is correct and if so why.
    You will note the statement assumes the white balance is correct and
    says even then you can have poor color.

    So rephrasing my question -- how can colors be wrong when the white
    balance is correct?

    jim evans, Oct 21, 2005
  8. jim evans

    Mark² Guest

    That fire engine appears as one version of "red" at sunset, and another
    version of "red" during mid-day.
    The "red" you wish to depict in your image IS, in fact, up to you to the
    extent you control your camera's rendition.
    No it doesn't. It assumes that the present WB settings on any camera CANNOT
    be preset to account for the limitless variations of lighting soources that
    exist all over the place.
    That's a very large assumption.
    What do you mean by "set correctly"?
    Do you mean a custom white balance?
    Or do you simply mean one of the preset WB choices offered by your camera
    (sunny, cloudy, shade, etc.)?
    If it's the second one, then you will find that SOMETIMES it works--when in
    a very typical sunny scene, or 100% flourescent-lighted room...but its
    common to have a mixture of light qualities/sources, each with a different
    color cast that mixes with others (sunlight through a big window, but
    flourescent lighting inside). This means that neither sunny WB nor
    flourescent camera WB settings will be accurate. This is where creating a
    custom WB is beneficial...or...taking the time to tweak the color balance in
    photoshop after the fact.
    I think there is still some question as to what you are referring to as
    "correct WB is set."
    They shouldn't be, unless you've over or under-exposed the image.
    But still, I suspect you may not be as "correct" as you think.
    Explain further so we can answer your question:
    -How are you determining that your WB settings are "correct?"
    What basis are you using to establish your certainty of this?
    I'm not challenging you... It's just that without knowing what you mean, it
    leaves a huge question mark which prevents a helpful, accurate answer.
    Mark², Oct 21, 2005
  9. jim evans

    Steve Wolfe Guest

    I read in google groups where someone posted this statement in this
    Partly so. It's not because white balance shouldn't set all of the colors
    correctly in theory, it's because of real-world deviations from the ideal.
    Different sensors (or monitors, printers, or any other color-related device)
    will have some non-linearity in how receptive they are to colors at
    different intensities. Put another way, they will react somewhat
    differently to a red object that's brightly lit than if it is not brightly
    lit. To make it even better, each of the colors will behave differently as
    well - it won't react the same way to a bright blue ball as to a bright red

    Here's an example - take a monitor calibration device, and set the white
    point correctly on a monitor - either LCD or CRT. Does that make the colors
    look right? Nope, not at all - the device will need to go through and
    analyze the color response to different colors and different intensities to
    create a custom profile.

    As for your camera, the firmware is sufficiently aware of the properties
    of the average sensor in that model to get things pretty close. If it's not
    close enough, there is a part in "Real World Camera Raw" that goes over how
    to set the various parameters in ACR to match your individual camera. I
    suspect that "Real World Color Management" would go to even greater lengths.
    You can also get products from the various color-management companies that
    will develop a custom profile to match your camera's specifics.

    All of that being said, you need to take it with a grain of salt. Your
    camera will do a reasonable job of getting close enough if the white balance
    is correct. Besides that, in the majority of photography, you rarely want
    100% accurate color anyway. Most of the time you're trying to manipulate
    things to make them look flattering, not accurate - in fact, it's common to
    completely discard color, and shoot black and white when color won't be
    flattering. Look at pictures of newborns, the great majority of them are
    B&W, as they usually have complexions that aren't terribly flattering in
    color. Even when you're shooting a color picture, you generally try to
    emphasize certain hues or colors. In the end, most photographs are about
    what you WANT them to be.

    Steve Wolfe, Oct 21, 2005
  10. jim evans

    Chris Brown Guest

    Therin lies the rub. Adjusting the white balance so that the grey card is
    grey can make the colours wrong in some images (think sunsets), or may not
    even be possible in others (think sodium light).

    In a nutshell, if white balance is set from a grey card then the colours
    will be wrong if the grey card didn't look grey to the photographer when she
    took the picture.
    Chris Brown, Oct 21, 2005
  11. jim evans

    kctan Guest

    The term white balance means to balance the color temperature of light so
    that white object (a piece of white card) will reproduce as white. The known
    color "Gray" will look gray and the unknown colors will look right
    physically. But a physically corrected color may not have mood or the effect
    that a photographer trying to express. For example the sunset mood, the
    white should look warm, but if you WB correctly, it looks like a sunny day
    in the noon. We can purposely use the incorrect WB to create visual impact.
    Therefore physically, correct WB means correct color but not artistically.

    kctan, Oct 21, 2005
  12. jim evans

    jim evans Guest

    Does this mean the ACR parameters for my camera that come with the ACR
    can be improved on? Without realizing it I have been assuming they
    were calibrated using a color standard in such a way that each color
    gets converted into it's exact numeric value.
    I need accurate color for what I'm doing.

    jim evans, Oct 21, 2005
  13. [snip]

    Yes, they often can be improved on. I think what typically happens is
    that a particular camera is different from the one of that type that
    Adobe used to generate the data that comes with ACR. I actually used a
    script that started off being based on the ideas in Bruce's book, from:

    There are other scripts too. See the Adobe forums. I haven't tried any
    of them yet.
    Barry Pearson, Oct 21, 2005
  14. jim evans

    Jim Guest

    That may be what you mean, but to everybody else it means that the camera
    sees white under the existing lighting as R=G=B=255. I should also observe
    that the white point is not identical between gamuts.
    What you setting is the midpoint.
    Jim, Oct 21, 2005
  15. jim evans

    jim evans Guest

    Hmm . . . interesting. That's logical. I just never thought of it
    before. I assume it's possible a given sensor may drift with age too.
    If so, this would mean the profile needs to be regenerated
    occasionally, just like monitors, require recalibration.

    jim evans, Oct 21, 2005
  16. jim evans

    scarface Guest

    scarface, Oct 21, 2005
  17. jim evans

    scarface Guest

    scarface, Oct 21, 2005
  18. jim evans

    Marvin Guest

    It will happen if your monitor or your printer are distorting the colors. The camera is
    just the first step in a chain.
    Marvin, Oct 21, 2005
  19. jim evans

    jim evans Guest

    I don't think the monitor can cause the intrinsic image to be the
    wrong color if the white balance is correct. That is, if a known gray
    in the image *measures* gray (R=G=B) it doesn't matter what color it
    appears to the eye, the actual image is correct.

    jim evans, Oct 22, 2005
  20. jim evans

    Mark² Guest

    The image?
    I think you mean the "actual data" is correct.
    Mark², Oct 22, 2005
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