making WB change gradual over time

megabit wrote on 7/22/2008, 5:40 AM

Sometimes, it's difficult or impossible to anticipate the best WB setting for the new environment/venue you never shot before. You have to re-balance while shooting. The problem begins when the very moment the WB is changed, happens to be the precious moment you just can't afford to cut away from the final recording.

What are your measures to replace the abrupt WB change with a longer lasting, gradual change? Any automation for this?

Comments

farss wrote on 7/22/2008, 7:18 AM

I assume you mean fixing it in post.

Just add a keyframe in the CC tool at the point you want to start the change from then move along the point where you want the change to complete at and make the change to correct the WB. Vegas will automatically add a keyframe at that point.

As I'm certain you're aware though, nothing beats getting it right in the camera. Even if you can't, at least having two presets in camera for daylight and tungsten so you're at least in the right ballpark so only a minor tweak is needed in post helps a lot.

One thing that I do like in Ppro is the auto white balance FX. I had a DB camera tape where they'd forget to switch to tungsten for one the interior shots. That FX in Ppro did put it right better than I've ever seen it done in Vegas. In all fairness to Vegas though I was starting with 10bit 4:2:2. That's the first time I really saw what a difference those uber expensive cameras can make.

Bob.

johnmeyer wrote on 7/22/2008, 8:33 AM

Another method of gradually changing anything is to put exactly the same video on two tracks and snap them so they are in absolutely the identical position (make sure Quantize to Frames is on -- this should be on whenever editing video). Then, apply your color correction to one of these two. You can use the Color Corrector, Secondary Color Corrector, the Mike Crash auto levels plugin (although it may only do levels and not color -- I've not used it). Anyway, when you've got what you want, just fade out the top track and put the identical, inverse (i.e., fade in) transition on the track below. The effect will fade in (or out) over whatever time you wish and will be smooth as can be.

megabit wrote on 7/22/2008, 8:43 AM

Thanks guys for the replies!

Bob - yes, of course I mean just a slight change (from my PP's 3200K to some 3000K, which I found more appropriate while shooting; my other PP has 2600K which was way too low). Unfortunately, the EX1 doesn't have the feature of adjusting WB my small increments while shooting, like the V1 has - so I need to make for it in post.

John - your idea sounds great; I'll check it as soon as I have more time, and report the results.

megabit wrote on 7/24/2008, 9:47 AM

OK, so I was supposed to report on the results of ironing out an abrupt WB change, but... well, after taking another look at my video, I have noticed that with my WB changed from 3200 to some 3000K, and due to having used the STD1 gamma on my EX1 - I have a much worse problem to deal with in post!

Now, I am totally aware this might be an easy stuff for most of you guys, but I'm certainly lacking experience. If you take a look at this video:

http://www.vimeo.com/1380497?pg=transcoded_embed&sec=1380497

- you will certainly notice that the musician's face is over-exposed, and too reddish. This means that:

- I should have probably stayed with 3200K and not go down with WB

- trying to squeeze all available light (my EX1's spotmeter was complaining about too low light), I should have remembered my red channel was getting too much of it...

Oh, well - I would probably have got it right, if I had RGB scopes rather than the simple luminance histogram, or a big hi-res monitor instead of my EX1's LCD. But it's what it is, and my kind request for help is:

Which Vegas tool(s) should I use to make the face look right? My problem is that I tried the Color Corrector, Color Corrector (Secondary), Color Balance, Levels, and what not... Yet I'm still not quite satisfied with the results.

As I think what I did here is quite a common type of recording mistake, I believe a well-established and proven method of correcting this exists.

Just what is it?

PS. I should have added perhaps that my only excuse for such a basic recording error was my being too preoccupied with preventing the dim background from introducing noise into my video, which could be very distracting... Any comments welcome!

JackW wrote on 7/24/2008, 11:54 AM

Try "Curves," which will let you tweek the reds alone, which should help.

Jack

lynn1102 wrote on 7/24/2008, 5:24 PM

From what I'm seeing, if you didn't try it already, it looks like it may work just to drop the luminance a little bit. Overall brightness would stay the same so the noise shouldn't be a problem.

Lynn

lynn1102 wrote on 7/25/2008, 10:51 AM

Just re-read my post - must have been a bad day - I meant to say drop the chroma levels a bit. Sorry

Lynn

megabit wrote on 7/26/2008, 3:31 AM

I added Curves and Chroma level to my arsenal, but still am not satisfied with the results.

I'm now coming to the conclusion that my error basically consisted in unnecessarily changing the WB from 3200K (my preset) to anything lower than that, which nicely simplifies the problem back to the original topic of this thread:

- how to revert back to the WB I got at 3200K in the portion of the video, shot at a lower colour temp setting (2900 or 3000K, if I remember correctly). Only now, I'm not after replacing the abrupt WB change with a smoother one, but simply reverting back to the original look of 3200K WB preset I started my shootng with.

Of course, all the tools mentioned in the posts above do work, more or less. But what I'm seeking is a method of matching the WB to that of the fist portion of my video, and I mean matching it EXACTLY. Is there a way to pick (by a mouse click) a certain area in the video shot with 3200K, and instruct Vegas to automatically change the WB of the other portion (shot with 2900K) to that?

I may be mistaken, but I think such a method does exist in Edius (can't check it now as my trial has expired).

If no Vegas FX offers that, I'm open to suggestion about some third-party plugins. I guess it'd be a good investment to buy one (if it exists), as colour balancing is a bit awkward in EX1, its Auto WB being sluggish, to say the least. I never had such problems with the prosumer V1E, which I used in Auto WB most of the time and never had problems like this...

Still waiting for some help; TIA

Piotr

farss wrote on 7/26/2008, 5:39 AM

Having at last looked at the clip (Vimeo is getting SLOW) my advice is to leave it as is. The highlights on the face are clipped so trying to correct that will be very problematic and it's not that bad anyway.
If you'd shot that in a studio where the performance was for the camera and you had control of the lighting then you might deserve a flogging but you didn't and no one should/would take you to task for how it looks. If you'd eased back a bit on the exposure to avoid the clipping you'd have gotten a very dark image.
Part of your problem might have started from the angle you were shooting at but you probably had no control over that either. And after all your viewers should be watching the performance not your skills as a videographer.

Bob.

megabit wrote on 7/26/2008, 5:57 AM

Sound advice as always, Bob - thanks :)