How to liquify or reshape a face in a photo

Reshaping a face is the job of Fluid Warp in Paint by Zaweba, its liquify tool, opened with Filter > Fluid Warp (Ctrl+Shift+X). Push and pull areas with the warp brushes, or place the Face Guide by hand over the eyes, nose and mouth and use its sliders to change eye size, nose width, smile, jawline and face width. The whole change applies as one undo step.

Liquify is used for everything from fixing a fold in a shirt to a subtle tidy of a portrait. Used lightly it's invisible; overdone, it's the most obvious edit there is.

The warp brushes

Fluid Warp opens in its own window. Forward warp pushes pixels along with the brush, the tool you'll use most. Reconstruct paints back towards the original, smooth evens out lumpy warps, twirl clockwise and anticlockwise spin pixels, pucker shrinks towards the centre, bloat swells outwards, and push left slides pixels sideways along your stroke. Freeze protects an area so nothing moves there, and thaw unfreezes it.

Brush size, density, pressure and rate set how the brush behaves. Use a big brush with low pressure for natural reshaping; small brushes create ripples.

You can show the mesh, the mask and a backdrop to see what's moving. Reconstruct All and Restore All undo the warp across the whole picture. Meshes save as .ptmesh files, so you can apply the same warp again later.

Using the Face Guide

Press G in Fluid Warp to place the Face Guide. Drag an oval around the face, then place the eyes, nose and mouth. Faces aren't found automatically, so take a moment to place them accurately, since the sliders work from those points.

The sliders cover eye size, height, width, tilt and distance; nose height and width; smile, upper and lower lip, mouth width and height; and forehead, chin height, jawline and face width. Small moves go a long way. A couple of points on a slider is often enough.

Step by step with face warps

Duplicate the layer first. Open Fluid Warp. Freeze anything near the face that mustn't bend, such as a door frame, a horizon or the edge of a table, because warping a face next to a straight line bends the line too and gives the edit away. Make your changes with the Face Guide or the brushes, then check by toggling the backdrop. Apply, and compare with the untouched layer.

Keeping it believable

Respect the person. Retouching that changes someone's features should be done with their agreement, and for official photos such as passports it isn't allowed at all.

Watch the background and the hair. Pulling in a jaw drags the background with it, and hair edges can stretch. Freeze or restore those spots.

Step away and look again. Liquify edits creep: each looks fine next to the last, but compared with the original the face has changed too much. Lower the layer opacity to dial it back.

Paint by Zaweba is free software for Windows that runs offline, so portraits are edited on your own computer.