White balance, factor or offset?

Discussion in 'Digital Photography' started by Volker Hetzer, Mar 14, 2005.

  1. Hi!
    How does the white balancing work? Does the camera derive a fixed offset
    for each channel or a factor to multiply each channel with? (I imagine
    it ought to be a factor otherwise black and white would become difficult
    to do for the cam.)

    The reason is I sometimes take picture in difficult lighting conditions
    (buildings at night) and I'd like to try separating the white balance
    out of the shooting. So, what I plan to do is to shoot one exposure
    series with normal daylight white balance and take lots of pictures
    of a warmcard set using all the different lamps lighting the building
    (also normal daylight balance).

    Later at home I'd like to recolor the images of the building
    with the white balances of the warmcards.

    (Btw, does anyone have an idea on how to do this in photoshop
    elements?)

    Lots of Greetings and Thanks!
    Volker
     
    Volker Hetzer, Mar 14, 2005
    #1
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  2. Sounds like fun...if you like standing around outside at night and not
    knowing what you are going to get. While you are at it spend a few more
    seconds and take a RAW file (which does not white balance). Then you can do
    all those adjustments you enjoy at your computer in a comfortable
    chair...but that doesn't sound like as much fun.

    "Volker Hetzer" <> wrote in message
    news:d13eeu$joe$-online.net...
    > Hi!
    > How does the white balancing work? Does the camera derive a fixed offset
    > for each channel or a factor to multiply each channel with? (I imagine
    > it ought to be a factor otherwise black and white would become difficult
    > to do for the cam.)
    >
    > The reason is I sometimes take picture in difficult lighting conditions
    > (buildings at night) and I'd like to try separating the white balance
    > out of the shooting. So, what I plan to do is to shoot one exposure
    > series with normal daylight white balance and take lots of pictures
    > of a warmcard set using all the different lamps lighting the building
    > (also normal daylight balance).
    >
    > Later at home I'd like to recolor the images of the building
    > with the white balances of the warmcards.
    >
    > (Btw, does anyone have an idea on how to do this in photoshop
    > elements?)
    >
    > Lots of Greetings and Thanks!
    > Volker
     
    Gene Palmiter, Mar 14, 2005
    #2
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  3. Volker Hetzer

    paul Guest

    Volker Hetzer wrote:
    > Hi!
    > How does the white balancing work? Does the camera derive a fixed offset
    > for each channel or a factor to multiply each channel with? (I imagine
    > it ought to be a factor otherwise black and white would become difficult
    > to do for the cam.)
    >
    > The reason is I sometimes take picture in difficult lighting conditions
    > (buildings at night) and I'd like to try separating the white balance
    > out of the shooting. So, what I plan to do is to shoot one exposure
    > series with normal daylight white balance and take lots of pictures
    > of a warmcard set using all the different lamps lighting the building
    > (also normal daylight balance).
    >
    > Later at home I'd like to recolor the images of the building
    > with the white balances of the warmcards.
    >
    > (Btw, does anyone have an idea on how to do this in photoshop
    > elements?)



    I'm not understanding your questions. I never heard of a warm card, just
    gray card. Normally, just one gray card shot is needed (for each
    setting) so why take many card shots? Anyways I'll try to explain what I
    understand about the isssue.

    The ideal answer to your question is to shoot RAW instead of jpeg mode
    but I guess that's not an option for your camera. Still, take a look at
    the manual under white balance. There might be a way to set custom white
    balance by shooting a card & have that apply to all pics afterwards.

    I have full PS and with that, you can Save out a levels setting, then in
    another photo, add a levels adjustment layer & Load the saved settings.
    I'm not sure if you can do that in Elements. This assumes you want to
    use the eyedropper on the gray card to establish RGB adjustments.

    I believe certain RAW conversion programs can do their magic on jpeg
    files also. That would help you if it's true.

    Image > Adjust > Color balance seems the best PS tool for adjusting WB
    in jpegs. That has three sliders:

    cyan > red
    magenta > green
    yellow > blue


    PS RAW plugin has two sliders:

    temperature:
    blue > orange

    tint:
    green > magenta

    Temperature seems the most important, tint is secondary. I'm not sure if
    those are exactly the colors adjusted, just my guess by looking at it.

    I heard mentioned here recently that the orange street lights are almost
    impossible to correct WB for. I think it's the blue channel that is
    almost completely missing.

    Now I have another question. How do people handle this with film?
     
    paul, Mar 14, 2005
    #3
  4. Volker Hetzer

    Jim Townsend Guest

    Volker Hetzer wrote:

    > Hi!
    > How does the white balancing work? Does the camera derive a fixed offset
    > for each channel or a factor to multiply each channel with? (I imagine
    > it ought to be a factor otherwise black and white would become difficult
    > to do for the cam.)
    >
    > The reason is I sometimes take picture in difficult lighting conditions
    > (buildings at night) and I'd like to try separating the white balance
    > out of the shooting. So, what I plan to do is to shoot one exposure
    > series with normal daylight white balance and take lots of pictures
    > of a warmcard set using all the different lamps lighting the building
    > (also normal daylight balance).
    >
    > Later at home I'd like to recolor the images of the building
    > with the white balances of the warmcards.
    >
    > (Btw, does anyone have an idea on how to do this in photoshop
    > elements?)


    You don't say what camera you're using so it's tough to
    give a precise answer..

    If you want to adjust white balance after the fact and your
    camera supports RAW, use that.

    There's just no better way because there is no white balance
    applied to RAW files. The white balance is applied when you
    convert them into standard formats (like JPG or TIF)..

    With suitable software, you can do all your color balancing
    on your computer.
     
    Jim Townsend, Mar 14, 2005
    #4
  5. >
    > I'm not understanding your questions. I never heard of a warm card, just
    > gray card. Normally, just one gray card shot is needed (for each
    > setting) so why take many card shots? Anyways I'll try to explain what I
    > understand about the isssue.


    Warm cards come in a set of several slightly different shads of a sort of
    blue green. By white balancing on them you force the camera to take warmer
    photos...sort of like the golden hours near dawn and dusk. There is also a
    card for counteracting florescent lights. The concept was designed for
    videographers but recently a set was designed for digital still cameras that
    also comes with a grey card. www.warmcards.com (I think...maybe no "s")
     
    Gene Palmiter, Mar 14, 2005
    #5
  6. Gene Palmiter wrote:
    > Sounds like fun...if you like standing around outside at night and not
    > knowing what you are going to get. While you are at it spend a few more
    > seconds and take a RAW file (which does not white balance). Then you can do
    > all those adjustments you enjoy at your computer in a comfortable
    > chair...but that doesn't sound like as much fun.

    Of course I'm taking raw shots. Nevertheless, if you watch them, the
    recorded white balance gets added to it.
    Besides, I do want some more hints from the original scene, and these
    are the white samples of differently coloured sheets.

    Greetings!
    Volker
     
    Volker Hetzer, Mar 16, 2005
    #6
  7. paul wrote:

    > The ideal answer to your question is to shoot RAW instead of jpeg mode
    > but I guess that's not an option for your camera. Still, take a look at
    > the manual under white balance. There might be a way to set custom white
    > balance by shooting a card & have that apply to all pics afterwards.

    Yes, I will use raw (coolpix 5000) but I don't think I'll be able
    to come up with good pictures by just trying out different settings.
    warmcards are slightly bluish cards which, when used for white balancing
    give a red cast. As a beginner I'm simply trusting that they did a better
    job than I can do. Normally I would have to white balance with such
    a card then shoot then white balance with another or the same in different
    light (my motives are lighted with at least two different lights) and so
    on.
    I am hoping to cut from NoOfWhites times NoOfExposures to NoOfWhites
    plus NoOfExposures.

    >
    > I have full PS and with that, you can Save out a levels setting, then in
    > another photo, add a levels adjustment layer & Load the saved settings.
    > I'm not sure if you can do that in Elements. This assumes you want to
    > use the eyedropper on the gray card to establish RGB adjustments.

    Yes, that's what I'm trying. I'll see whether I can do that in elements.


    > Image > Adjust > Color balance seems the best PS tool for adjusting WB
    > in jpegs. That has three sliders:
    >
    > cyan > red
    > magenta > green
    > yellow > blue
    >
    >
    > PS RAW plugin has two sliders:
    >
    > temperature:
    > blue > orange
    >
    > tint:
    > green > magenta


    Thanks for the hints!


    > I heard mentioned here recently that the orange street lights are almost
    > impossible to correct WB for. I think it's the blue channel that is
    > almost completely missing.
    >
    > Now I have another question. How do people handle this with film?

    They don't. I have seen this when trying to get a decent picture of Eilenan
    Donan Castle in Scotland. I spent two evenenings on it (yellow, incandescend
    and halogene lights at the same time) and in the end I got one picture which
    as a novice I could barely live with. The colours of the postcards in the shop
    were totally irrational compared to that.

    This easter I'm having another go at tower bridge which is much more complex
    and would be impossible to shoot like I did the castle. (Last time I took
    about 150 pictures with none really satisfying me.) That is why I think
    about taking the colour balance separately from the motive and combine them
    at home.

    Lots of Greetings!
    Volker
     
    Volker Hetzer, Mar 16, 2005
    #7
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