Make a transparent background

What a transparent background actually is

A transparent background is an alpha channel: a fourth value stored for every pixel that says how see-through it is. The checkerboard you see in editors is not part of the file. It is just how software draws "nothing here." Only formats with an alpha channel can hold it. The PNG specification defines one, and so does WebP, which Google says supports transparency in both its lossless and lossy modes. JPG has no alpha channel at all, which is why a JPG download from WipeMark gets a white background.

Edge pixels matter more than people expect. A good cut-out does not jump from fully solid to fully clear. Around hair, fur and soft focus, the edge pixels are partly transparent, so the subject blends into whatever you later put behind it.

How WipeMark makes the background transparent

The tool sends a reduced copy of your photo, at most 1024 pixels on the long side, to WipeMark's server. The model there (BiRefNet, a segmentation model built for high-resolution images) returns a mask. Your browser then applies that mask to your original, full-size photo, so the download has the same pixel dimensions you uploaded. Nothing is stored or logged on the server. The whole round trip takes about 20 seconds.

Photos that give the cleanest result

Contrast between subject and background is the single biggest factor. A dark mug on a light table separates far more cleanly than a gray cat on a gray sofa. A few habits help:

• Keep the subject whole. Objects cut off by the frame edge come out with a hard straight line where the photo ends.
• Avoid busy backgrounds behind thin parts. Chair legs, bike spokes and plant stems in front of clutter are where the mask most often guesses wrong.
• Shoot a little larger than you need. You can always shrink a clean cut-out. Enlarging one later makes the edge look soft.

Common problems and how to fix them

A thin colored outline around the subject. This is the old background bleeding into partly transparent edge pixels. It shows most when you place a subject shot on green grass onto white. Use the Erase brush at a small size along the edge, or pick a new background close in tone to the old one.

Holes inside the subject. Gaps between an arm and a body, or the inside of a mug handle, are meant to be transparent. If the model left them filled, paint them out with Erase. If it cut away something solid, such as a white collar against a white wall, paint it back with Restore.

Glass and see-through objects. A wine glass or a plastic bottle is partly see-through in real life, and the model has to decide which parts are object and which are background. Expect to touch these up by hand.

Which format to download

Download PNG when the image is going into a document, slide deck, print file or any tool where you are not sure what is supported. Download WebP when it is going on a website. Google's own measurements put lossless WebP at 26 percent smaller than PNG. Choose JPG only when you actually want a white background and a smaller file, because the transparency is gone the moment you save it.