Replace the background of a photo

The gradient runs from a top colour to a bottom colour, and with two well-chosen values it imitates a photographer's lit backdrop. Take two shades of one hue, the lighter one on top: light grey over mid grey, pale blue over a deeper blue. The eye reads the change as light falling from above, which is how studios are lit. Two unrelated colours, purple into orange for example, give the look of a poster and suit event graphics and social posts better than portraits.

Keep the difference between the two shades modest. A gradient that travels from white to black within one frame draws more attention than the person in front of it.

On the Pro plan the new background can be any picture. It is scaled until it covers the frame of your subject photo and cropped where it overhangs, so pick one with the same orientation, and at least as many pixels as the photo it sits behind; a small picture stretched over a large frame turns soft.

Three things make a composite believable. The camera height should agree: a person photographed at eye level looks wrong against a scene shot from above. The light should come from the same side. And the background should be a little out of focus, the way it would be behind a real subject. A background that is sharp from front to back is what gives most composites away.

Typical jobs are a product placed in a room or on a worktop for a shop page, a portrait moved from a kitchen onto a neutral backdrop, a seasonal background for a greeting, a consistent setting for a row of profile pictures. For these a replaced background is ordinary image editing.

It is not acceptable everywhere. Many countries do not accept identity photos that have been digitally altered. Listings for used goods, property and vehicles are expected to show the item as it really is. And where a picture documents an event, changing its setting changes what it says. If in doubt, say that the image is a composite.