Blur Background

Vignette Blur, Not Portrait Mode

A phone's portrait mode builds a depth map from two lenses or a neural network and blurs by distance. This does none of that. It blurs everything outside a circle or a rectangle that you position yourself, which makes it a vignette — or, with a wide flat rectangle, a tilt-shift. Used deliberately the effect is good. Used as a stand-in for depth of field it looks wrong, because anything at the same distance as your subject still goes soft if it falls outside the shape.

How the composite is assembled

The picture is drawn twice: once through a blur filter and once sharp. A gradient mask keeps the sharp copy only inside your focus shape, and the two layers are stacked. Nothing in that chain has any idea what the photograph contains.

The radius is a real measurement

Blur radius is specified in pixels of the exported image, and the on-screen version scales that radius by the same factor it scales the picture. What you see is what you download. A 12 px radius that looks strong on a 900 px web image is barely perceptible on a 6,000 px original, so choose the radius while thinking about the size at which the image will finally be published.

Feathering, which now works

Feathering controls how gradually the sharp region gives way to the blur. At zero the boundary is a visible ring that announces the edit to anyone looking. Pushed toward the top of its range the transition spreads across a large part of the frame and the result reads as atmosphere rather than as an effect.

This control was broken until recently — the value was interpreted in the wrong units and changed nothing on the canvas. If you tried it before and concluded it was decorative, it is worth another look.

Placing the focus

Tap or click anywhere on the preview to move the centre point. Two percentage boxes accept exact values, which is what you want when a set of images needs the focus in the same place. The focus size slider sets the extent of the shape: for a circle it is a proportion of the shorter edge, and for a rectangle it scales both sides of the frame together.

When the effect gives itself away

Two things expose it. The first is a subject that extends beyond the focus shape, so an arm or a shoulder softens halfway along its length. The second is a background object that stays sharp because it happens to sit inside the circle while everything at its distance is blurred. The fix for either is to move the shape, widen it, or accept a gentler radius.

Reasonable uses: hiding a messy room behind a product, calming a busy street behind a portrait taken from far enough away, and pulling the eye toward one panel of a documentation screenshot.

Blur is not redaction

Do not use this to hide a face, a licence plate or an address. The region is chosen by geometry rather than by content, the strength is a slider rather than a guarantee, and a blur that looks impenetrable at preview size can still leave recoverable structure. When something must not be in the picture, cut it out of the frame with Crop Image instead, and check what the file says about itself with Image Metadata Viewer before you send it anywhere.