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Old December 17th, 2007, 07:48 AM   #1
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Default CCD Color Temperature?

Are Digital Cameras and Video Cameras different in the way they handle white balance?

I was always under the impression that CCDs in video cameras are set to 3200K by default. Some videographers prefer to use an 85B filter outdoors so as to avoid the pink fringing produced by the different peaking of the RGB channels.

Now, I'm told that digital cameras are the opposite in the way they handle white balance because of the Bayer pattern.

I'm trying to understand the differences between the two. Can someone explain that?

Thanks.
Adam Palomer is offline   Reply With Quote
Old December 17th, 2007, 12:27 PM   #2
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1- You kind of need two numbers to describe a particular shade of color / white balance. Describing colors in Kelvins ignores how green/magenta a color is. Unfortunately most people just describe colors in Kelvins.

2- Just my guess...

On some professional cameras, there is a filter wheel that will optically white balance the camera for particular presets. Optical filters can lower the amount of r/g/b light hitting the sensor so that r g and b are balanced.

If you don't do this:
A- You can do electronic white balance to get the rest of the way there. However, you will not get the best signal-to-noise ratio. Why this happens is because one/two of the channels will overexpose before the rest. By doing electronic white balance, you usually just add digital/electronic gain/exposure which will make the other channels intentionally "overexpose"+clip to balance out the channels.
B- Or, you can try to guess the missing highlight information in one of the channels. I think only the Red camera does this (and it does not have a filter wheel).

3- With a film camera, you need optical filters to get the white balance right. The film stock can't do electronic white balance. Or you can try to fix it in telecine.

Quote:
Some videographers prefer to use an 85B filter outdoors so as to avoid the pink fringing produced by the different peaking of the RGB channels.

Now, I'm told that digital cameras are the opposite in the way they handle white balance because of the Bayer pattern.
I don't really know what they're talking about.
Glenn Chan is offline   Reply
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