What's the difference between "Offset | Gamma | Gain"

[MisterStylow]

Could somebody explain to me, what these do in color grading language.

When should I use offset, gamma and gain...

Offset:

Gamma:

Gain:

[Faintscrawl]

I have the same question.

Back to Google I go.

[Dennis Weinmann · Accepted solution]

Offset controls Shadows/Blacks of an image. It does this by changing the brightness/color levels while leaving midtones and highlight areas unaffected.

Gamma = Midtones (middle gray levels)

Gain = Highlights/Whites

Check out a grayout mode (Color/Gray,Color/Black,White/Black)  to illustrate each level

You can adjust threshold between levels with the sliders (M/H,S/M) on left/right

Example:

Source Image:                                                                                                                                           Offset (Black/White)

Gamma (Black/White)                                                                                                                             Gain(Black/White)

I'd recommend to take a look at http://helpx.adobe.com/speedgrade/topics.html toget started

In particular:

http://helpx.adobe.com/content/help/en/speedgrade/using/balance-blacks-whites.html

http://helpx.adobe.com/content/help/en/speedgrade/using/set-gamma.html

[MisterStylow]

Aaah I thought so, but I wasn't sure about it!

Thanks for your explanation! really helpful

Greets,

Stylow

[Chris Smith x0h00]

Although there are ranges you can set between Shadows, Midtones, and Highlights, Offset, gamma, Gain are traditionally fairly simple math to the overall image.  They are a main part of primary color correction.  Meaning in your Overall tab you can and should use Offset Gamma Gain as much as possible to get your image where you want it before you start messing with other things.

The old school math for them is offset is just addition, Gain is just multiplication, and gamma is a power function curve.  Although rebalancing offset and gain with each other can be a hassle so it seems like some color systems like Resolve are range mapping the lows and high bewteen your input video and your output video and having gamma still a be a power function in there.

But using those controls you can set the levels, the amount of contrast or lack of, and bias all kind of color casts for wildly different effects.  For example, pushing the offset very blue but then going opposite with the gamma to rebalance the mids can give your blaks that instamatic blue/black look that everyone is crazy about.  Classic gain (which is multiplication) as it's pushed to a specific color is the same as putting a colored filter over the camera when you were shooting. 

Personally I don't like using ranges to color with (shadows/mids/highlights), I prefer using the different math properties of offset/gamma/gain under a "master" or "Overall" mode.