Best sequence of Levels, White balance, Secondary Color Correction

ritsmer wrote on 1/4/2023, 2:45 AM

Working on a skiing project recorded with different cameras over several years (!!) there are quite a few challenges in keeping the snow the same flavor of white through the scenes.

It is nothing, however, that hard work can not solve - but:

It seems to me that some Vegas Pro (using ver 20) FX's like Levels and Secondary Color Correction are "static" while i.e. White Balance is "dynamic" - meaning that a once set White Balance responds to changes made to Levels lying before White Balance in the FX sequence for that clip.

Example: A situation occours if you have i.e. the FX sequence Levels - White Balance - well set - but then, at a later review, want to adjust the brightness of the snow but not much of other things but the snow.

This can be done nicely by changing the Levels Input-or-output end - but it seems that the White Balance perceives that change and responds to it by changing the White Balance of the clip. So it seems that Levels should be after White Balance ? making me wonder if Levels should not normally be preferred before White Balance if you have a camera which needs some adjustment of Levels Input Start in order to (re-)gain some needed contrast ?

So I wonder if there is a Rule of Thumb how one should build such a FX sequence ?

Possibly the issue could also be solved by having a Levels FX both before (to remedy some low camera contrast) - but also after the White Balance in order to make it possible to make later changes without influencing the once set white balance.

Comments

RogerS wrote on 1/4/2023, 3:11 AM

I'd do white balance first at the media level but if you can't see what you're doing fix levels and revisit white balance. If there are tweaks that need to be done at an event level for consistency that can be done on each event building upon the adjustment already applied to the media.

Wolfgang S. wrote on 1/4/2023, 4:29 AM

Typically, what colorists will tell you, is to adjust the luminance in a first step always. And then perform the adjustment colors. The reason for that is, the our eyes tend to see the luminance changes in a more significant strength then changes in the color. So the typical approach should be, to appyl the level filter, and then the color correction filter.

Using Vegas Pro 20, I would tend to use the color correction panel instead of the older level filters. But if it works for you, why not use those filters?

Musicvid wrote on 1/4/2023, 9:10 AM

So it seems that Levels should be after White Balance ?

Very good question. I'm still wrapping my head around the hierarchy in the Grading Panel, but I already have some objections. Yours bears further testing and consideration.

First thoughts, and two very different cases here.

In a 10 bit (float) project

I would apply WB early, but not before colorspace transforms if used, obviously. I "might" set my output levels to a serviceable range first if they were absolutely horrid and tweak them later.

In an 8 bit (integer) project

A Levels Filter to nail down the output to 16-235 for delivery in a Legacy project must always go very last in the chain. Other filters, Sharpen is one example, can blow the output luminance to the stratosphere if applied post-levels.

Don't know that it makes that much difference in a VP18-20 8 bit Fullrange project. Although there is certainly an optimum math-based hierarchy, a different filter order may give a more pleasing initial visual result, making the discussion academic. If you're asking, I still set Levels at the Output.

Musicvid wrote on 1/4/2023, 12:00 PM

@ritsmer To test your observation, I used a calibrated 3500K test ramp, and White Balanced inside the linear curve portion using the Auto feature. Not perfect, but good enough for a demo.

I then adjusted the Levels in the Grading Panel. I was unable to measure any color changes, at least until a clip point was reached by overshifting the sliders. Keep your eyes on the Vectorscope and Histogram. This may be what you're seeing, but the filters hierarchy does not appear to have an effect on the output Chroma, only Luminance.