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Thread: Gray Card Color Balancing

  1. #1
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    Default Gray Card Color Balancing

    Hmm...has anyone done color balancing wiff a gray card before?

    here are the results i tried out wiff...



    This was with the cam at auto white balance. Notice the color cast on the label.



    This was with the cam custom set to gray card balance.

    Notice that the 2nd pic the whites are more accurate. Onli confusing thing IS...the 1st pic wiff the color cast was wat I saw!!!
    Believe it. And it will be so.

  2. #2
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    White balance should be set with a white card, not gray card (whether 18% or not)....
    Check out my wildlife pics at www.instagram.com/conrad_nature

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    OOPS... alamak...so the gray card is for exposure!? it did mention that white balance was set wiff the white side...but it's for video cams....hmm....let me check it out again
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  4. #4
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    ok...set balance wiff the WHITE side liao.

    here are the results...



    this was wiff the custom balance.



    this was taken wiff the auto white balance...hmm...ultimately there is still some color cast using autoWB
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  5. #5

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    I still find that your custom WB with the gray side looks more natural. Look at the white background behind the words 'CASIO' and you'll see what I mean. It looks whiter with the gray-calibrated WB. What do the rest think?

    I have heard and read many conflicting views on which side of the grey card to use for calibrating WB. So far I have found through trial and error that both the white and gray sides have almost the same WB effect. Some sites state the gray side is just a darker shade of white, and essentially it's the same as the white side (since the camera will calibrate to 18% gray - equiv to the gray side, even if you use the white side).

    Would like to hear it from the real experts. White side or gray side for calibrating WB?

    thanks.
    sfhuang

  6. #6

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    Me no expert.

    My understanding is that using Custom White Balance, the camera will render the scene by compensating the colour cast so that it would look like it was taken in white light (ie full spectrum sunlight). It does this with reference to an object which it knows to be white (ie the grey card). So if that object is orange, it will shift the colour curve until that object appears pure white, and everything else in the picture will be shifted the same way too.

    Your pictures were taken in room (incandescent) light. The objects are bathed in warm orange light, so that's why they have the colour cast, as seen by both your eyes and the camera in AWB mode.

    Theoretically I cannot think of any reason why there should be a difference between using the white side or the grey side of the card.

  7. #7
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    Hmm...actualli i think the gray side gives off a more "whitish" color too...actuali when i posted this was in a dilemma. the color cast by the light and taken with AWB was really in line with what i saw. but with the gray card calibration it gave a different look ie. what would occur under white light. so which should be the "correct" one?? to represent the "truth" or to show what it should have been under "sunlight" conditions...

    Originally posted by sfhuang
    I still find that your custom WB with the gray side looks more natural. Look at the white background behind the words 'CASIO' and you'll see what I mean. It looks whiter with the gray-calibrated WB. What do the rest think? I have heard and read many conflicting views on which side of the grey card to use for calibrating WB. So far I have found through trial and error that both the white and gray sides have almost the same WB effect. Some sites state the gray side is just a darker shade of white, and essentially it's the same as the white side (since the camera will calibrate to 18% gray - equiv to the gray side, even if you use the white side). sfhuang
    Believe it. And it will be so.

  8. #8

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    Basically, I feel that a true neutral grey card or white card will have no difference as they would only differ in luminance values and not chrominance.

    Anyway, as what streetshooter mentioned, using custom white balance on location is to create the effect as if one was shooting under white light. Sometimes, using AWB might be more desirable if you want to capture a little of the actual ambience.

  9. #9

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    Originally posted by Horus
    Hmm...actualli i think the gray side gives off a more "whitish" color too...actuali when i posted this was in a dilemma. the color cast by the light and taken with AWB was really in line with what i saw. but with the gray card calibration it gave a different look ie. what would occur under white light. so which should be the "correct" one?? to represent the "truth" or to show what it should have been under "sunlight" conditions...
    Interesting discussion!

    There are two points here. One is whether to use AWB (to represent true ambient colors) or to use CWB (to make whites look white). This I guess is up to the photographer i.e. what kind of ambience or colors he would like to depict in his picture.

    The other point is whether the gray side or white side of the card should be used. I have been using the gray side for custom WB calibration for some time now, and find that the colors are the same as when I use the white side for calibration. Your pictures above illustrate this point very well.

    But I am still hoping that some expert can come in and verify some of these empirical observations of mine ...

    cheers,
    sfhuang

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