White Balance

[Media Editor]

When setting the White Balance, is the Eye Dropper more effective than manually using the Temperature and Tint sliders?

[R Neil Haugen]

Not necessarily.

It just may be a slightly different pixel value you pick with the eyedropper compared to what you look at.

Either way you want to check your scopes. Neutral values should have the same location in the RGB Parade across the R, G, and B traces, plus be dead center in the Vectorscope YUV scope.

And of course White Balance controls work by changing the relative top point of each channel. Therefore having the most affect on very bright values, less on middle values, and almost no effect on shadows. Think of moving the far right point of the RGB Curves tool for each color channel. It's the same effect.

So if you have a color cast issue, affecting the whole image, WB controls can't fix that. At which point the Creative tab Shadow Tint control or the Shadow color  wheel control will need adjustment.

Neil

[rodneyb56060189]

That's a really good question. I sometimes use the eyedropper if it's a simple scene ( like a beach where someone is wearing a white hat ) just to see what happens, and then use " undo " ... maybe then use 'redo' and 'undo' again, just to see what it is doing. If it gets the job done then I leave it done.

[Ann Bens]

If you hold down the ctrl key when using the eyedropper it will sample 5x5 pixels instead of 3x3.

[rodneyb56060189]

I guess it's worth mentioning... some scenes have no pure white in them ( like a shot of some forest or whatever ).

White balance is matching the light source (measured in Kelvin degrees ) to the camera WB setting.  It gets a little more complicated in pro work on film sets, because the camera will shoot color chart (and tone scale) with dedicated light source to match the camera ( let's say you are shooting indoors with tunsten light ( 32K ) you would shoot the chart with a 32k light only. THEN, to get the mood you want, you may put color gels on the lights of the actual set ( for the scene and skin tones, etc. ) to make it warmer or cooler etc.

In that case the editor matches to the chart shot , and NOT the clips.

There are color temp meters and color correction gels available to control this stuff.

So, for most people, not working on pro sets, it's really a subjective choice how you want the skin tones to look, the green of trees, and your whites ( if there are any ).

That is why the eyedropper is not that reliable by itself as the only tool to try and get your proper look.

[Media Editor]

How do I know if the White Balance needs to be adjusted?

[R Neil Haugen]

There are two different parts to setting a base or neutral color, white balance and color casts. Either may be an issue.

White balance is an issue of the whites end points for the three color channels, R, G, and B being incorrectly set for the image probably in-camera. It's a situation that visually and by Vectorscope YUV traces affects only the mids and highlights.

A color cast on the other hand is an issue of color that is off throughout the image, clear through the shadows to the highlights. Again, seen by both a use of the Mark I eyeball and the Vectorscope YUV.

First, you need to have the Vectorscope YUV up in the Lumetri Scopes panel. Look at the center of the scope, where the two vector lines meet. That should be the place where there is no color, in other words, only black, gray, and white values. If you have some areas of the image that are clearly supposed to be totally neutral ... black/gray/white ... and there is discrete blob representing them very close to the center, but it isn't quite centered, that would tend to indicate a color cast.

If you have a sort of mis-shaped or mushed blob, that tends to indicate more of a white balance issue.

You can use either the white balance controls in the Basic tab or the Highlight Tint control in the Creative tab to adjust WB. Temp controls work by changing the relationship of the top white point of the Red channel agains the Blue channel, Tint controls work by balancing Red and Blue in tandem against the Green channel. So in the Basic tab you have two sliders, one for Temp and one for Tint. In the Creative tab, the tint balls do the same thing essentially.

If simply adjusting the WB and/or the Highlights tint cleans up the neutrals both visually and on the Vectorscope, you're done. If not ... use the Creative tab's Shadow Tint control to neutralize the shadows/mids. Again, you should end with the neutral "blob" in the scope centered on the crossing of the vector lines.

You can also use the HSL to set a key by Saturation only, limiting what passes through the key to the very lowest saturated color areas. Then use the Basic or Creative tab wn/tempt/tint contols while watching the Vectorscope to center the trace. This way you know your neutrals are neutral.

Neil

[Media Editor]

Thank you