Fix a backlit video

Auto exposure tries to make the whole frame average out to a mid grey. When a large part of the frame is a bright window or sky, the average is high, so the camera shortens the exposure. The background then looks correct and everything in front of it, which is lit only by the dim room or the shade, drops several stops. The difference between a sunlit sky and a face in shade can easily be five stops or more, beyond what a phone video can hold in one exposure.

Exposure multiplies every pixel, so it would brighten the background by the same factor as the face and push it into white. Shadows instead targets the lower part of the tonal range and fades out towards the top, so the face comes up while the window barely moves. Highlights does the opposite for the top quarter. Together they reduce the contrast between subject and background, which is exactly what a backlit shot needs.

Avoiding the “HDR look”

Pushed too far, a big shadow lift and a big highlight pull make the picture look flat and grey, with halos of unnatural brightness. Keep Strength at the lowest value where the face is clear, and add a few points of Contrast back if it starts to look lifeless. Moving Blacks slightly left restores depth to the darkest parts.

• True silhouettes: if the subject was recorded as pure black, there is no detail to recover. You can only lighten the shape.
• Blown backgrounds: a window that is already solid white stays white. Lowering Highlights makes it grey rather than revealing the view.
• Noise on the face: lifted shadows show grain, especially on skin. A moderate Noise reduction helps; too much makes skin look plastic.
• Colour shifts: shade is bluer than sunlight. If a lifted face looks cold, lowering Saturation a little makes the cast less obvious.

• Turn the person or yourself so the window or sun is to the side or behind the camera.
• On a phone, tap the face to set exposure there; the background will brighten, so watch that it doesn’t clip completely.
• Bounce light into the face with anything white: a sheet of paper, a wall, a reflector.
• Use your phone’s HDR video mode where available; it records more range, giving you more to work with later.

For a clip that is dark all over rather than backlit, start with Auto brighten on a dark video instead. For phone-only fixes, see how iPhone and Android handle shadows in their own editors.