If you want to know whether a background remover is any good, give it a photo of someone with curly hair in front of a busy background. Hair is where cheap tools fall apart, and where good ones earn their keep.
Why hair is hard
Hair isn't a solid object with an edge. Near the outline, individual strands are thinner than a pixel, so each pixel there is a mix of hair colour and background colour. A simple cut-out has to decide "keep" or "remove" for each pixel, which gives you either a helmet of chopped hair or a fuzzy halo of background.
Good background removal predicts how much of each pixel is hair — a value between 0 and 1 called alpha. That's what lets strands look soft and natural.
The second problem: colour spill
Even with perfect alpha, the hair pixels still contain some of the old background's colour. Place someone photographed against a green hedge onto white, and you'll see a faint green glow in their hair.
Fixing that requires estimating what colour the hair would be without the background mixed in. We do this on every image, which is why our cut-outs don't carry a coloured fringe onto new backgrounds.
How to shoot photos that cut out well
- Contrast between hair and background. Dark hair on a light wall is easy; dark hair on a dark sofa is hard.
- Soft, even light. Hard backlight creates glowing outlines that are hard to separate.
- Plain backgrounds help, but aren't required. A decent model handles busy backgrounds; it just has an easier time with plain ones.
- Sharp focus on the edges. Portrait-mode blur on your phone can smear the hair into the background before the cut-out even starts.
How to check the result
Put the cut-out on a dark background, then on a bright one. Zoom to 100% around the hairline. You're looking for:
- Strands that end naturally, not in a sharp line
- No coloured glow from the old background
- No chunks of background caught between curls
Try it with your own toughest photo on the background remover — choose Person for portraits.
FAQ
Why does my cut-out hair look blocky?
The tool is making a hard yes/no decision per pixel instead of soft alpha. Try a tool that uses alpha matting, and upload the highest-resolution photo you have.
Does phone portrait mode help?
Not really. Portrait-mode blur mixes hair edges with the background, which makes clean separation harder.
