Transparent images: why backgrounds turn white
A transparent image is one where some pixels have no colour at all, so whatever is behind them shows through. It is essential for logos, stickers, product cut-outs and anything placed over another background, and it is lost in more ways than most people expect.
How it works: the alpha channel
An ordinary image stores three numbers per pixel: red, green and blue. An image with transparency stores a fourth, alpha, which says how opaque the pixel is. 255 is fully solid, 0 is fully see-through, and everything between is partly transparent.
The "everything between" is the important part. The edge of a cut-out hair, a soft drop shadow, the anti-aliased outline of a round logo — all of those are semi-transparent pixels. A format that only supports on-or-off transparency cannot represent them.
Which formats support it
| Format | Transparency |
|---|---|
| PNG | Full alpha, lossless. The safe default. |
| WebP | Full alpha, lossy or lossless. Much smaller than PNG. |
| AVIF | Full alpha. Smaller again, slower to encode. |
| SVG | Yes; vector shapes simply have nothing behind them. |
| GIF | On or off only. Soft edges become jagged. |
| JPG | None. |
That last row is the source of most problems. JPEG has no alpha channel at all. It is not a setting you can turn on.
Why transparency turns white (or black)
You converted to JPG. The converter has to put some colour in those pixels, because JPEG cannot store "nothing". Most choose white; some choose black. Keep the file as PNG or WebP with the image converter and the transparency survives.
The site you uploaded to converted it. Many platforms re-encode every upload to JPEG to save bandwidth. There is nothing you can do on your side except choose the background colour yourself before uploading, so it is at least the right one. The transparency tool flattens a PNG onto any colour you choose.
It was never transparent. The grey-and-white checkerboard in a downloaded "transparent PNG" is sometimes painted into the image. If the checkerboard moves when you zoom, it is real transparency; if it scales with the picture, it is pixels, and the file has no alpha at all.
The halo problem
Cut an object out of a white background, place it on a dark one, and you often get a thin pale fringe around it. This is called a halo or matte line.
It happens because edge pixels were blended with the original background. A half-transparent pixel at the edge of the object is half object colour and half white. On white that looks correct. On black it looks like a glowing outline.
Fixes, in order of effort:
- Place it on a background similar to the one it was cut from.
- Tighten the cut so the edge sits a pixel or two inside the object.
- Cut it out again from a background closer to the colour it will end up on.
Removing a background in the first place
The right tool depends on what is behind the subject.
- A flat, even colour — a green screen, a white studio sweep, a logo on a solid box. The chroma key tool removes a colour by threshold, runs in your browser and is free. It is precise and predictable when the background really is one colour.
- A real-world scene — a person in a room, a product on a table. A colour threshold cannot tell the subject from the background there. The background remover uses an AI model for this; it runs on our servers and uses credits.
Either way, save the result as PNG or WebP. Saving a fresh cut-out as JPG throws the whole job away.
Keeping files small
A transparent PNG photo can be very large, because PNG is lossless. If the image is going on a website, WebP with alpha is usually a fraction of the size with no visible difference. Our format guide has the numbers.