Not-So-White Balance

GenJerDan

GenJerDan

Veteran
OK. A) I hope I ask this so it makes sense, and B) I hope "Lighting" is a reasonable place to ask.

When you "White Balance" to something other than White, what happens? Do the colors shift in one direction or another along a 'rainbow' of colors - or does it 'turn' a color wheel, bring other colors up around the back side.

Damn. That makes no sense at all.

OK. If you tell the camera that Red is White, things that are really white go greenish. What happens to the other colors? I don't have a color chart to do any real testing.

This is just theory/curiosity question. No practical reason at the moment. (Although I could imagine things like "I need the sky to be bluer...balance to a <some color> card...)

Dan
 
Re: Not-So-White Balance

It's too late to be figuring this out...but I tend to think of white balance as being more of a phase adjustment. I mean, that's not exactly what it does, but it's similar.

You tell a camera that blue white is white, it biases towards orange. You tell a camera orange white is white, it biases towards blue...but those corrections don't really increase the chroma of a given color, they just shift the neutral point around.

If you white balance an orange white, it biases towards blue...but that wouldn't make a sky bluer, it just makes everything bluer. It doesn't actually raise the level of blue, it just shifts more of the pixels towards blue.

Ugh...I can't translate my mind this late in the day, but it's an interesting question.
 
Re: Not-So-White Balance

So it may be more of a warmer/cooler result, rather than a bizarro "wrong" result...

Dan
 
Re: Not-So-White Balance

Well, it does do a bizarro wrong effect, but not one that I see as visually interesting. I haven't experimented a lot with it though.

As far as an effect, it's not as practical as doing it in post either way.
 
Re: Not-So-White Balance

Look up "warmcards"... those guys are selling a product based around the exact idea you're talking about: white balancing to something other than white, to influence the color.

As for what the exact effect is, I don't know, but I'm sure it could be figured out with a little testing...
 
Re: Not-So-White Balance

I could the point of doing it "live" rather than in post...if you want the entire film to be moved warmer or looer. Or possibly even cooler.

I don't know about anyone else, but it's a pain in the butt for me to change each "event" (in Vegas).

Yes, I know it can be done automatically...I just haven't gotten that far yet. :D

Dan
 
Re: Not-So-White Balance

Well, I'm new at all this, but I'm a bit surprised by the responses so far. I thought using warm cards was more common based on what I've read. It is a good question, and something that *is* used. Here's an excerpt from an article at cybercollege.com.

Excerpt:

The process of skewing camera color balance is sometimes used in productions to create certain effects. For example, in the award-winning film, Traffic, director Steven Soderbergh gave different locations specific color tones. Scenes in Washington, D.C. were given cold blue tones, and the scenes in the San Diego area were warm with gold overtones. Often, you will see commercials skewed strongly toward blue or yellow-gold.

I guess they aren't doing this solely with camera settings and lighting...(Or are they?) Here's the the link to the whole article:

http://www.cybercollege.com/tvp018.htm

-Jerry
 
Re: Not-So-White Balance

I think Traffic was shot on Reversal Stock and treated chemically (as well as some post work) to achieve the look you are referring to.
 
Re: Not-So-White Balance

There aren't really any "settings" in a film camera, most color tricks are either created optically with filters, or chemically through processing and printing, or through gelling the lights to be the color they want while shooting, or some combination of the three.
 
Re: Not-So-White Balance

Well, I think white balancing to warmer and cooler tones for effect is pretty standard, but I was assuming the original post was referring more to extreme shifts in color...ie, color balancing "red" as "white".

If you're talking about color shifts in the warmer and cooler area, then yes...it's way easier to do it in production rather then post.  That's what a large part of color cinematography is about...playing with different stock (settings), filters, and varied CT lights.
 
Re: Not-So-White Balance

The DVX100 has 3 CCD's, each covered with a red, green, or blue filter.  The CCD's produce voltages related to the amount of light striking the surface.  When you white balance, you're telling the camera that for a given set of voltages produced by each CCD, you want the digital signal output to be neutral (R value =G value = B value).  White, or any shade of gray is always defined by equal R, G, and B values.  When you use a warm card, you're tricking the camera by saying this set of CCD voltages should be neutral when in fact, the card is slightly blue.  Because the card is blue, it produces a slightly higher voltage for the blue CCD.  So the camera says, okay I need these voltages to output equal R, G, and B values.  After you balance to the warm card and film a white card (or anything in the same light), the blue CCD sees less blue and produces a slightly lower voltage.  The lower voltage on the Blue CCD is converted to a lower digital B value relative to the R, G, and B values.  For example, if you were to film a white card (after balancing to the warm card), the reference set of voltages would produce something like 235, 235, 205 for the R, G, and B values, respectively.  Because there are equal amounts of extra R and G, you get a warm cast because Red plus Green equals yellow.
 
Re: Not-So-White Balance

yeah barry, you...took the words right outta...

Okay, you didn't. Thanks for the susinct response.

I'm a photoshop curves junkie, so I should have been able to answer this clearly. I just couldn't wrap my brain around it as well as you did.
 
Re: Not-So-White Balance

Ditto on the thanks.

Now...I wonder what would happen if I fed the audio output from channel A into the XLR input of channel B and...

;)

Dan
 
Re: Not-So-White Balance

I've always used Warm Cards. I didn't realize how much better things looked until we lost them and had to balance off of a white card. The footage was barely usable when you put it next to the interviews where we had the cards. Thankfully, we found them 10 minutes later.
 
Re: Not-So-White Balance

from my experience, balancing from a certain color card gives you the exact opposite and equal value color on the RGB color wheel. Value meaning its grey scale comparison. Meaning if you took out the color its tonal value in grey scale would look the same. This be art school talk. I knew light, color and design class would come in handy some day.
 
Re: Not-So-White Balance

Is it true that you get the exact same effect

"Or, you could just raise or lower the color temperature in the scene file. "

than using warm cards?

-Jerry
 
Re: Not-So-White Balance

Don't know whether it's EXACTLY the same, but it sure looks like it. If you've got WarmCards, try experimenting a little...
 
Re: Not-So-White Balance

Can you make your own instead of buying them? Is there something special about the shade of blue they use?
 
You must log in or register to reply here.
Back
Top