How to make a video brighter or less grainy

Dark, grainy footage can be improved in Cut by Zaweba's Filters tab. Raise brightness and contrast a little, lift saturation if colours look flat, and turn on denoise, light or strong, to calm the speckle. Show the filters in the preview from the View menu so you can judge the result live, then save through a preset.

The app is free software under the EULA and works offline, so your videos stay on your PC.

Why videos come out dark and grainy

A camera in poor light has two choices: give a dark picture, or boost the signal and bring up noise with it. Phones often do the second, which is why indoor and evening clips look gritty. Old camcorders add their own grain, and footage copied from tapes can be both dim and noisy. Brightening and denoising work on these two problems from opposite ends, so they're best used together and gently.

Brightening and cleaning up a clip

Open the clip in Cut and, if you only need part of it, mark in with I and out with O. Step to a frame that shows the problem well, perhaps a face in shadow or a dark wall where the grain is easy to see.

Turn on View, then Show the filters in the preview. Now every change shows on the picture as you make it.

In the Filters tab, raise brightness a little. Then raise contrast a touch too. Brightness on its own tends to turn blacks grey and makes the picture look washed out; a small contrast boost keeps the darks dark while the rest comes up. If colours have gone dull, nudge saturation up.

Next, turn on denoise. Light is the place to start. Strong is for footage where the grain is heavy, such as an old tape or a very dark room. Under the hood, Cut uses FFmpeg's atadenoise filter for light and its nlmeans filter for strong, and you can see the difference best on plain areas like walls and sky.

When it looks right, go to the Convert tab and choose a preset, such as Best quality if you want to keep as much detail as you can, or For YouTube 1080p, For WhatsApp or Small file if the clip is going somewhere specific. The estimated size and encoder are shown first, and only the kept parts are converted, with the filters applied.

Judging how far to go

Push and pull back. Raise a setting until it's clearly too much, then bring it back by about half. It's a quick way to find the point where the picture looks better rather than just different.

Denoise after you brighten, not instead of it. Brightening reveals grain that was hidden in shadow, so it's best to see how much is there once the picture is lighter.

Don't overdo the strong setting. Heavy noise reduction smooths skin into something waxy and blurs fine textures like hair and grass. If faces start to look painted, drop back to light.

Leave sharpening until last, if you use it at all. Sharpen in Cut has light and strong settings too, but sharpening a noisy picture sharpens the noise. On a cleaned up clip a light touch can bring back a little crispness.

Old interlaced footage

If the clip came from an old camcorder or a television recording and shows thin comb-like lines on anything moving, tick deinterlace as well. It's in the same Filters tab and fixes a different problem from grain, but old footage often needs both.

Fixing a whole folder

When a set of clips was all shot in the same dim room, set the filters once and add the files from the Batch tab. Each one gets the same brightness, contrast and denoise, and the queue runs in the background, saving after every change, so it carries on after a restart.

Cut by Zaweba won't turn a dark phone clip into studio footage. It will make it far nicer to watch.