About BgImage: the background workbench
BgImage does one family of jobs: whatever needs doing to the background of a picture. Take it off, make it transparent, put the subject on white, blue or any colour, blur it, or put a new background behind it. And when the background does not exist yet, make it here too, at the exact pixel size you need.
Why the picture stays on your device
Most background removers receive your photo on a server, cut it out there and send back a result, often a small preview with the full-size file behind a credit. This site turns that round. The page downloads a cut-out model to your browser once, and every picture is processed on your own computer or phone. Nothing about your picture is sent anywhere, so there is nothing to meter: the download is full size, with no account and no watermark.
The flat jobs, taking a white box off a logo or lifting a signature off paper, need no model at all. They are pixel arithmetic and run the moment you drop the file.
How the cut-out works
There are two models: a portrait model (25 MB) for people and an object model (84 MB) for products, pets and everything else. The model reads a working copy about 1400 pixels across; the mask it draws is scaled back up and applied to your original pixels, the colour of the old background is taken out of soft edges such as hair, and the brushes let you erase or restore by hand. The file that downloads is the size of the picture you opened.
How the background maker works
The maker draws backgrounds from numbers. Every colour is held as a lightness, a chroma and a hue, and converted to sRGB only when a pixel is written, so a gradient blends the way it looks rather than the way the numbers fall. Noise and dither are functions of the pixel position, which is why a design can be reproduced exactly from its link. Large exports are drawn in horizontal bands inside a worker thread, so the page stays responsive while the full-size canvas is filled.
What it leaves out
No account, no saved projects and no server-side processing of any kind. A made background is kept by keeping its link, because the whole design is written into the address. There is no programming interface for other software to call, because nothing here runs on a server.
Who keeps it
BgImage is an independent site, free to use, with nothing to buy. Questions, corrections and pictures it gets wrong are welcome through the contact page.
Pictures you open and backgrounds you draw never leave this page. They are cut out and drawn by your browser, and the file is written straight to your disk.