When you increase your gain or ISO settings, you make your sensor more sensitive to light, which can help you properly expose your footage when there isn’t enough light hitting your sensor. However, by increasing your sensor's sensitivity to light, you can create noise and grain in your image. The best way to get cleaner footage is to have the gain off and to have ISO at its lowest setting, but there are ways to remove grain in post production.
You can use editing software like After Effects to sharpen your videos up and get rid of any unwanted grain and noise. How do you do that? Watch this tutorial from Surfaced Studio that demonstrates how you can banish noise and grain from your videos in After Effects.
Tobias Gleissenberger, the guy behind Surfaced Studio, starts off by exporting the clip he wants to touch up from Premiere Pro to After Effects; you can remove noise in Premiere Pro, but it requires third-party plug-ins, and Gleissenberger wants to show you can de-grain without any plug-ins.
Once in After Effects, Gleissenberger goes to the effects and presets panel and searches for the “Remove Grain” effect. Once applied, the effect gives you a little preview window that you can drag around your clip see what it would look like with the grain removed. From there you can apply the effect to the entire clip by changing its viewing mode from preview to final output.
The effect ends up removing a large amount of grain from Gleissenberger’s clip, but there is more that needs to be done. While the effect did get rid of a lot of the fine grain noise, there’s still some blockly noise. Gleissenberger says the way to remove this is to enable temporal filtering.
He goes into a few more settings that you can tweak. When you remove grain and noise, it smoothes out the image that can leave things looking artificial. So you have to find a good middle ground between removing grain and keeping the original details in your subjects.
Ideally, it’s always best to try and avoid getting grain in your videos by keeping your ISOs low and keeping gain off, but sometimes it can’t be avoided. When those situations arise, you go to editing programs like After Effects to remove the grain and noise, and as you can see from Tobias Gleissenberger, they can be removed pretty well.