Make Background Transparent

Logos on white, product photos on a seamless backdrop, signatures on paper and green-screen frames all share one thing: a background of a single colour. This tool finds that colour, makes it transparent with smooth, clean edges, and can drop in a new solid colour or another picture behind your subject. It runs in your browser with plain colour maths, so it is fast and private — and it is honest about its limits.

How to use this tool

1. Choose one or more images with a plain background.
2. Leave the background colour on “Detect from the edges”, or pick white, black, green screen, blue screen or a custom hex colour.
3. Adjust the tolerance (how close a colour must be to count as background) and the soft edge for anti-aliased outlines.
4. Keep “Only background touching the edges” so same-coloured parts inside your subject survive; switch to “every matching pixel” to also clear holes, such as the inside of the letter O.
5. Keep it transparent (PNG or WebP) or choose a new background colour or image, then download.

Formula

distance = √((R − Rₖ)² + (G − Gₖ)² + (B − Bₖ)²) ÷ 441.7 × 100%

Pixels within the tolerance become fully transparent; those between the tolerance and tolerance + soft edge get partial transparency a, and their colour is un-mixed from the background with F = K + (C − K) ÷ a, which removes the coloured fringe. With green or blue screens, spill on the edges is reduced by limiting the key channel to the larger of the other two. 441.7 = √3 × 255 is the largest possible RGB distance.

Example

A 1200 × 1200 px product photo on pure white with tolerance 15% and soft edge 8% treats every pixel within 66 RGB units of white as background (15% of 441.7) and fades out those up to 102 units away. A light-grey shadow at (225, 225, 225) is 52 units from white, so it disappears too; set the tolerance and the soft edge to 5% each (44 units in total) to keep it.