Comments

GlennChan wrote on 12/25/2007, 12:46 AM
In my opinion...

You're better off not shooting them. You save time on set and you can do a reasonably good job in post of getting color consistency.

In post, what you would do is to compare stills from previous/next shots (and also from shots that are in the same location) and make them match well enough via color correction. Color correction is essentially a cheat (mathematically it doesn't really match the numbers up right), but it works well enough in practice. e.g. camera manufacturers have different knee algorithms and they don't look the same.

Even if you had shot a color chart that wouldn't really help.

*On the other hand, in some situations color charts (e.g. Chroma du Monde) can be helpful to make cameras match.

2- If you look at most Hollywood films, they are color timed by varying printer lights... these are really primitive color controls (and they don't have color charts). Audiences accept that and don't notice color variations from shot to shot.

3- It will really help color consistency to:
- Shoot your footage correctly... no overexposure/underexposure, get white balance right.
- Use the same model camera. (Ok, not always possible.)
- Shoot things at the right/same time of day. Although it's possible to do day for night, night for day, and make shots taken at different times of day match each other.

Basically we cheat and it tends to work. Remember: Hollywood has been doing it for decades.
farss wrote on 12/25/2007, 12:51 AM
Just a white and grey card would be more than adequate unless you require clinically accurate color. Make certain the white card isn't being clipped.
Use the CC tool in Vegas. Use the highlight dropper to sample the white card and the mid dropper to sample the grey card. The blacks always seem to me to take care of themselves although you can just set the blacks to the same angle as the mids and tweak the amount to taste.
Of course WBing off the white card to start with is a very good thing to do. Adjusting WB for every setup in a scene might not be such as wise thing to do. Depending on your light sources you might be adjusting out natural changes in color and introduce some horrid unnatural jumps in color balance across cuts. Always use the bluest light (usually daylight) to set WB in a scene. The eye accepts warm colors from incandescent lamps and candle, it revolts at the look of blue light coming in a window.

Bob.
Grazie wrote on 12/25/2007, 1:05 AM
Glenn - yes!

Now, everybody, re-read this from Bob! A true Christmas gift, if there ever was, should be torn open up and used! Oh, no NEED for batteries either.

"Depending on your light sources you might be adjusting out natural changes in color and introduce some horrid unnatural jumps in color balance across cuts. Always use the bluest light (usually daylight) to set WB in a scene. The eye accepts warm colors from incandescent lamps and candle, "

Bob, what a most sensible, valuable and wise post - thanks man.

Grazie



essami wrote on 12/25/2007, 2:58 AM
thanks for the answers! Off to shop for a white and grey card, anyone know a good place in europe where to get one?

Thanks for the good advice!

Sami
farss wrote on 12/25/2007, 3:12 AM
DSC Labs sell them, I think they do a reasonably priced set of cards in a spiral bound book. Most of their other charts are very good, very expensive and have a limited life. Unless you're needing to match CGI work, testing / calibrating cameras etc probably overkill. Some of the really fancy charts in large sizes cost as much as a cheap camera. They are a nice mum and pop kind of business, they're not overcharging, printing things with precise colors is an expensive business and buying color charts and not replacing them when they expire is pointless.

Most photographic supply shops would have basic white and grey cards. Really they don't have to be absolutely precise, slight absolute errors for most things don't matter, being consistent is more important. A sheet of white paper is good enough for a WB.

Thanks for the kind words Grazie. That's something I've learned the hard way. There's now a roll of CTB gell and C47s (wooden pegs) in a kit box that's always in the car now :)

Bob.
GlennChan wrote on 12/25/2007, 11:46 AM
Even among sheets of white paper there are differences in their color.... put a bunch of white objects side by side and you'll see what I mean. Some paper I believe has a fluorescent dye added to it to make it look whiter... that's something you'd want to avoid. And of course old paper is slightly yellow-ish. But then again... it generally is good enough.
fausseplanete wrote on 12/27/2007, 6:23 AM
In a hotel recently I found the camera (Sony Z1) WB to be fooled by the low energy light bulbs in total use there. This was revealed by the purple stripes on my colleague's pullover looking blue, I opted to use manual adjustment. The apparent WB failure was possibly the result of uneven (spiky/dippy) wavelength profiles on the part of both the lighting and the camera. Of course this could have been fixed in post by CC but the less of it the better.

Apart from that, my first attempt to shoot then post-adjust to match a Gretag colour chart showed this not to be as simple as I first imagined, but further experimentation is planned.