Color Balance in Post

[Sam Roberts]

Coming from a video camera background I find the notion of rebalancing color in post interesting to say the least. But really how good is it?

Let's say I have a shot that starts indoors under tungsten light and I then follow a subject as he goes outdoors in one continual shot.

With a video camera you do a fast turn of the filter wheel as you go out the door and either cut around that or just leave it in (for that "COPS" reality look) If the camera is set for 3000K and you move outdoors without an edit, just how fixable is this? And is it possible in post to have the color balance change on the fly without it being too noticeable?

 

[Matthew Rogers]

Well, considering the white balance is just meta data and really is fixed at somewhere in the 5000k's (correct me if I am wrong...) you shouldn't have many issues. The only problem I see is how you are going from indoors to outdoors, or vice versa. Is it something you can do a fade and not see, or is it a hard cut that you have to somehow hide? I would say this kind of thing needs to be planned ahead if at all possible to make sure you get the best results.

Matthew

 

[GlennChan]

With a video camera you do a fast turn of the filter wheel as you go out the door and either cut around that or just leave it in (for that "COPS" reality look) If the camera is set for 3000K and you move outdoors without an edit, just how fixable is this?

On one HD camera I've played with:
A- The viewfinder is black and white so you can't spot WB issues on it.
B- You can store WB presets and do a 3/5 second fade between two presets. BUT, you have to plan this beforehand and get both WB settings.
Red AFAIK can't do that.

In run and gun shooting, I would see this getting fixed in post. Because you wouldn't have video knee enabled, you shouldn't get as wacky results fixing the white balance. (But some NLEs don't have very good white balance fixing algorithms, or they aren't easy to use.) But this kind of thing you could fix in post.

2- Hmm I don't think this is a situation I see on TV very often.
I don't think a fast turn of the filter wheel would look very good in any situation... though maybe in the future it'll become a stylistic thing (like right now we cut to a shot where the camera is racking into focus, zooming in, etc.). Red doesn't have a filter wheel so you couldn't do that (not that it's technically correct).

As far as changing white balance in post goes, that's what all dSLRs do. It's valid and it works well... and it's something video cameras do too.

 

[T. Glen Phelps]

There is no difference in setting a white balance in camera or in post. This in not a video camera, it is a RAW camera just like a digital SLR.

 

[Luis Otero]

There is no difference in setting a white balance in camera or in post. This in not a video camera, it is a RAW camera just like a digital SLR.

Amen. The on-camera WB is only, in my opinion, for reference on how it will look at that specific level. However, once you bring it to Redcine, you can manipulate it to have every footage to look the way you WANT it by just adjusting the Color Temp. So, do not worry of the way it was shot: RAW gives you all the freedom to change it at will.

 

[jimhare]

I have heard there are pitfalls in correcting 3200k because you have to push the already weak blue channel quite a bit, so noise might be a problem.

 

[Luis Otero]

I have heard there are pitfalls in correcting 3200k because you have to push the already weak blue channel quite a bit, so noise might be a problem.

This is true during a traditional CC, but if you use RAW, you just modify the metadata, and that type of issues in minimal to no present. Think of RAW as an image in which you can "recreate" or even go back in time to the day of shooting, and by changing the parameters, it will look as if you would have use that specific parameter that day.

When you change the WB during shooting, it is only for your reference (monitor how it will look), but when you open the RAW, it is just plain and you play with it as you wish. Even exposure! That is why it is advised to underexpose; if you underexpose you have the details there, just hidden. On the other hand, if you overexpose, the clipped data cannot be recovered. This is not valid for filters that you use that will alter the images recorded, as Pro-mist, etc. In those cases, the RAW will reflect such "destructive" images, so you cannot go back and get a clean image from the original R3D. That is why I advocate such effects to be done in post, even it it takes long rendering times.

See these examples I posted before (not final, just for example). RAW, quick CC on Redcine, and a more "aggressive" change of look:

 

[Patrick Tresch]

Hello,

You can also consider the R G B of your CMO as 3 diffenrent captors that captures R G and B values at same level if you expose at 5000k - 6000k.

When exposing at 3200 kelvin, you underexpose your Blue channel of about 2 stops. Yes it's not as dramatically as in a YUV world as you can compensate your RAW footage to the right white balance but your tradeoff is 2 stops of gain (noise) in the blue channel.

So in brief try to always expose for 5000k (minimum : as there are smaller losses in the Red channel even at 10000k).

But,

When working in lowlight condition where you are at the limit of T stops, in a 3200k (or less) ambient, I would rather not put a CTB filter as it would also decrease Red and Green sensitivity. It would be probably better to have a poor Blue channel but keep R and G as high as possible. We have been used to the perception of lowlight condition to be more grainy.

I would definitly work with correction filters when possible.

I would also consider using IR filters if working in highliy lit conditions where you have to put a lot of ND's and you don't want to shoot at higher shutter speed (see IR thread).

Postproduction is great, but sometimes too late...

See you.

Pat

 

[Bang WOW Bang]

This is true during a traditional CC, but if you use RAW, you just modify the metadata, and that type of issues in minimal to no present. Think of RAW as an image in which you can "recreate" or even go back in time to the day of shooting, and by changing the parameters, it will look as if you would have use that specific parameter that day.

When you change the WB during shooting, it is only for your reference (monitor how it will look), but when you open the RAW, it is just plain and you play with it as you wish. Even exposure! That is why it is advised to underexpose; if you underexpose you have the details there, just hidden. On the other hand, if you overexpose, the clipped data cannot be recovered. This is not valid for filters that you use that will alter the images recorded, as Pro-mist, etc. In those cases, the RAW will reflect such "destructive" images, so you cannot go back and get a clean image from the original R3D. That is why I advocate such effects to be done in post, even it it takes long rendering times.

See these examples I posted before (not final, just for example). RAW, quick CC on Redcine, and a more "aggressive" change of look:

Good advise to all RED shooters, ands sometimes only " Primary Color color correction " is not enough, and do try the 2nd color Grading with unlimited layers with masking in any desired objects.

My best .-

Best regards,



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[Hans von Sonntag]

Hi Pat,

just to let you know: Great summary!

Hans