Remove green background from photo
Drop a photo shot against a green or blue backdrop and the screen is keyed out on arrival. What you download is a transparent PNG at the full resolution of the original — not a downscaled web image, not a flattened JPEG. The file never leaves your machine.
What a transparent PNG actually gives you
Most “remove background” tools hand back a JPEG, and a JPEG cannot store transparency at all — the holes get filled with white or black and the cutout is only ever as good as the moment you saved it. A PNG carries an alpha channel: every pixel keeps a fourth value saying how opaque it is, so the edges stay soft and the file can be dropped onto any other background later without re-doing the work.
That is what makes the result usable beyond one place: a slide deck, a product listing, a print-on-demand upload that asks for a transparent cutout, or a compositing app. One file, no re-export.
How to do it here
- Open the tool and drop the photo in — PNG, JPEG, WebP, BMP and AVIF where your browser supports it, plus paste-from-clipboard. The key runs straight away.
- Check the key colour. It is read from the border of the frame, so a clean shot usually needs nothing. If auto-detect grabbed the wrong thing, set the colour by hand or use Pick from media and click the backdrop.
- Nudge Tolerance, Edge and Spill. Tolerance is how far from the key colour a pixel can sit and still count as background. Edge trims the thin green rim off the outline or softens a jagged one. Spill pulls the green light that bounced off the screen back out of hair, shoulders and light clothing.
- Download the transparent PNG. It comes out at the resolution of the original.
Why photos are harder than they look
A still gives you one frame, which sounds easier than a clip — and it is, until the backdrop is not uniform. One photo has to be solved with one global threshold, and a real screen is almost never one colour: light falls off towards the corners, fabric wrinkles, a shadow crosses part of it. The keyer measures distance in the Cb/Cr plane and ignores brightness, which is what lets a shadowed screen still key out — but only up to a point.
On our synthetic shade ramp, at the shipped tolerance of 25 the backdrop stops keying out once it falls to between 0.65 and 0.60 of full brightness: its chroma distance from the key reaches about 33.5, past the roughly 29.5 radius that tolerance 25 allows, and the pixel flips from fully transparent to fully solid. Raising tolerance to 50 keeps that same ramp keyed all the way down to 0.40, the darkest row in the file. So the usual fix for a screen with a shadow across it is more tolerance, not a different tool.
The other thing a real photo adds is compression. A JPEG has already smeared colour across the boundary, so the keyer is staring at a soft ring of mixed pixels instead of a clean edge — and a chroma key has nothing to work with there. Shoot or export PNG when you can.
When the auto-detected colour is slightly wrong
Auto-detect reads the border of the frame, and on a shadowed screen the border is darker than the rest of it. In our fixture run it recovers flat green and flat blue exactly, and a neutral white wall exactly — but on the shadowed variants it lands darker than the true backdrop: #00a23b where the screen is #00b140, a largest-channel difference of 15, and #009d39 with a difference of 20 once spill is in the picture too. That is small enough to key fine in practice, and it is worth knowing that “the tool picked the wrong green” is usually this, not a bug: pick the colour off a lit part of the screen by hand and the shadow stops mattering.
About that Edge slider
Edge is not a blur you can set once and forget, and the default is not always the best value. In the edge sweep at tolerance 25, the flat spill fixture scores a perfect IoU of 1.000 at edge 0, and drifts down to 0.889 at the far end of the range. The shadowed fixture behaves differently: its best score is 0.964 around edge −30, and it falls off a cliff after that — 0.905 at −20, 0.702 at −10, and 0.623 at the default 0. Same slider, opposite answer, because the two images have different problems. Move it while watching the outline, not by rule.
Those are generated fixtures — smooth ramps with no camera noise, no fabric texture and no compression — so read them as the shape of the problem, not a promise about your photo. The full measurement is on the chroma key benchmark page, the CSV files are in the reference repository, and the write-up is archived at doi.org/10.5281/zenodo.22916767.
When this does not work
Every page on this site has to say where the tool stops. For stills, that is:
- Semi-transparent detail. Flyaway hair over a busy background, fur, veils, smoke, glass, anything with motion blur in it. A colour key produces one matte; those need a hand-drawn mask or a rotoscope. This page does not have a brush, and it does not pretend to.
- A subject that is itself green. Green clothing, a green prop, or a green cast in the lighting gets keyed out along with the screen. Raising tolerance makes it worse. Shoot on blue instead — see the blue screen page.
- Backdrops that are lit and shadowed in the same frame. One global threshold covers one or the other. The ramp above is exactly this failure, measured.
- Neutral backdrops. White, grey and black all sit at the same point in the Cb/Cr plane, so a chroma key cannot tell a white wall from a white shirt. When the key colour has almost no saturation the page switches to a luminance key, which can separate them by brightness — and cannot separate a white shirt from a white wall of the same brightness.
- Wrinkled or uneven fabric. Every fold is a different shade of green. Steam it, stretch it, or light it flat; no slider fixes it.
- Heavily compressed or very small source files. There is no detail left at the edge to key against. Start from the largest, least compressed version you have.
- Anything involving a new background. This page stops at the key. It will not place your subject on another image, add a shadow, or export a JPEG. That is an editor's job.
Your photo stays on your machine
The whole key runs in the browser tab: decode, key, PNG encode, download. No upload step, no account, no queue, no watermark. For product photos, IDs and anything else you would rather not hand to a stranger's server, that is the part that matters — the no-upload page spells out what it avoids.