Co is Gamma? And How Does a Pro Colorist Use It?

What is gamma, and how should colorists use it in their color grading practice?

Gamma is one of those things we all have an idea about. We see it at work, but it’s likely that only a few of us have a clear understanding of what drives the behavior of gamma and when we want to use it. So let’s dive into DaVinci Resolve and get a clearer look for what gamma is, how it works, and when we should and shouldn’t use it.

What is gamma?

The simplest answer is that gamma makes the image brighter or darker. But gamma is a powerful tool, and it provides a huge function in the world of color grading. It’s worth having a more detailed understanding of how it actually behaves. To get that understanding, we’re going to use my favorite visual aid, the grayscale ramp.

As a visual aid, I’m using a grayscale ramp…

…to produce a straight-line waveform to demonstrate gamma.

As you can see, we have this beautiful line running all the way from zero to one. With this line in place, we can evaluate what exactly gamma does within the DaVinci Resolve Primaries. Take a look at what happens to the waveform when I spin the Gamma wheel around.

Here’s what happens when we move the Gamma wheel to the right…

…and what happens when we move Gamma to the left.

The line becomes either a rainbow or a hammock, depending on if we move the Gamma wheel to the left or to the right. But notice that neither the zero nor the one hundred values are changing. Absolute black and absolute white do not change when we move gamma. Gamma only moves everything in between.

Applications of gamma in color grading

This behavior has all kinds of useful, interesting applications in the world of color grading. One technical application is when we want to prioritize the transmission of a signal to a monitor. It turns out that gamma is a good way to fill in the low end of our available bit depth. That’s why we use things like Rec 709 Gamma 2.4, because that dis