How PicCutout works

1. Opening the picture

Your browser decodes the file on your device — JPG, PNG, WebP, GIF or AVIF, with the photo turned the right way up from its camera data. Photos larger than 12 megapixels are scaled down to 12 megapixels for working, which keeps brushes and sliders responsive; the site tells you when that happens.

2. Cutting

• Auto subject runs a salient-object model (88.1 MB) at 1024 × 1024 and stretches its result over your full picture.
• Person runs a portrait matting model (25.9 MB) that grades transparency along hair, or a quick person model (6.2 MB).
• Hand cut fills the loop you trace after thinning and smoothing it, so the edge is clean.
• Shape draws one of ten shapes at full resolution with anti-aliasing. “Centre on a face” uses a 230 KB face finder.
• Ink estimates the paper’s brightness around each point, divides it out to flatten shadows, picks a threshold automatically (Otsu’s method), and removes specks.
• Colour key takes the most common colour along the border, removes colours near it, and un-mixes it from soft edges.

3. The AI models

Models are not part of the website. The first time you choose an AI method, PicCutout shows the model’s size and asks before downloading it from our model file server. It is kept in this browser’s cache so it downloads once, and it runs on your device with ONNX Runtime Web — on the graphics chip where the browser supports WebGPU, otherwise on the processor. You can remove downloaded models at any time from the workspace or the privacy page.

4. Refining the edge

After an AI cut, small enclosed gaps — a see-through highlight on something shiny — are filled, while larger holes such as a cup handle stay open (you can switch this off). The Keep and Erase brushes paint the mask directly. Grow / shrink moves the edge by an exact number of pixels using a Euclidean distance transform; Soften edge blurs it. Undo keeps your last six brush and scissor edits.

5. Finishing and saving

Outline and sticker borders are measured from the same distance transform; the sticker border is then rounded off (dilated and eroded) so notches disappear, and a soft shadow is drawn from its shape. Files are encoded by the browser’s own PNG, WebP and JPEG encoders. WhatsApp stickers are fitted into 512 × 512 with a 16-pixel margin and re-encoded at lower WebP quality until they are under 100 KB, and the reached size is shown. ZIP files are assembled in the tab.

What leaves your device

Nothing about your pictures. The page itself, the sample pictures and — only after you agree — model files are downloaded. No request carries picture data, and there is no server that could receive it.