Bild unscharf machen

The tool runs three box blurs in a row, horizontally and then vertically. Three passes of a simple average come very close to a gaussian blur, the soft bell-shaped falloff photographers expect, and they take the same time whatever the radius, because each pass keeps a running sum instead of re-adding every neighbour. The radius you set is the spread of that gaussian in pixels.

Inside a box, the blur treats the box edge as the end of the picture: it repeats the border pixels rather than pulling in colour from outside, and pixels outside the box are never touched. Transparent areas of a PNG are weighted by their opacity, so a blurred logo does not grow a dark fringe.

A light blur is easy to see through. A familiar face can stay recognisable at a small radius, and large text can often be read through a moderate blur, which is why the tool shows a warning next to the slider. Judge it in the preview, not by the number. For a face, try 20 px or more on a typical phone photo. For plates, house numbers and anything printed, choose Solid black box under Inside the areas; it replaces the box with opaque black and nothing can be recovered from it.

Each image in the list has its own boxes. A file that has none while Selected areas is on is skipped and marked in the list, so an untouched copy is never saved by accident.

Whole image mode turns a busy photo into a calm backdrop for a slide, a video thumbnail or a page header, with text placed on top of it later. A blurred JPG also stores far less detail: a 224,092-byte 1200 × 800 test photo blurred at the default radius of 12 px and saved at quality 92 came to 53,145 bytes, under a quarter of its size.

The tool does not find the subject for you. It blurs the rectangles you draw, so a portrait-mode look, where a person stays sharp and everything around them goes soft, needs a phone’s portrait mode or an editor with masks. Boxes are fine for blurring a cluttered strip of a room or a screen in the corner of a photo.

Up to ten images, 50 MB each, in JPG, PNG, WebP or BMP. Keep the original format or switch to PNG, JPG or WebP; BMP comes out as PNG and JPG/WebP quality defaults to 92%. EXIF data, including GPS location, is not copied into the result. Large photos are processed one after another at full resolution, with the filter running in a background worker so the page stays responsive. On a recent laptop (Apple M3 Max, Chrome), a 12 MP photo blurred at radius 50 was ready in about 1.4 seconds and a 24 MP one in about 2.9 seconds.