Quick Mask: painting a selection with any brush

Selection tools draw outlines. Brushes paint. Quick Mask lets you paint an outline, which is often the most natural way to make a selection that's soft in some places and sharp in others. In Paint by Zaweba it's one key: Q.

What happens when you press Q

The current selection turns into a red overlay on the canvas. By default the red shows the masked area, the part that isn't selected, but Quick Mask Options lets you change the colour and opacity of the overlay and choose whether it shows the masked areas or the selected areas. Pick whatever reads best against your picture; red on a red-heavy photo isn't much help, so change it.

While the overlay is showing, you paint on it as you would on any layer. Black adds to the masked area, white removes from it, and grey gives a partial selection. You can use any brush, the pencil, the eraser, a gradient or the paint bucket.

Press Q again and the overlay turns back into a selection, marching ants and all. Both directions are undoable, so you can step back if you change your mind.

Why paint a selection

Some edges are best described by hand. A soft vignette around a face, a gradual fade across a sky, a selection that follows the uneven line of a hill: these are awkward with a lasso and easy with a soft brush. A gradient in Quick Mask makes a perfectly graded selection in one drag, which is a quick way to fade an adjustment across a picture.

Quick Mask is also the best way to clean up a selection made by another tool. Colour Range or Quick Selection might leave holes and stray specks. In Quick Mask they are obvious as gaps or blobs in the overlay, and a few dabs with black or white fix them.

Working habits

Use a hard brush for hard edges and a soft brush for soft ones. It sounds obvious, but many fuzzy cut-outs come from painting a crisp product edge with a soft brush.

Change brush size often. A big brush blocks in large areas quickly; a small one deals with corners. Zoom in for edge work and out to check the whole shape.

Use the bucket for big flat areas. If you need to mask out an entire background region that's enclosed by your painting, a click with black fills it.

Think about grey. Painting with mid grey gives a half selection, and any adjustment through it will apply at half strength there. That's useful on purpose and annoying by accident.

Where it fits

Quick Mask sits between the selection tools and the rest of the app. Make a rough selection with any tool, press Q to refine it with brushes, press Q to turn it back, then save it with Save Selection or turn it into a layer mask. Many people work this way for every important selection, because the overlay shows the selection's softness in a way marching ants never can.

Colour Range can also preview its result as a Quick Mask, so the look will already be familiar from there.

Small traps with the overlay

Painting on the picture instead of the mask happens if you forget whether Quick Mask is on. The overlay is your clue: if you see the red, you're painting the selection.

Leaving the overlay colour at red when the subject is red makes it hard to see what's selected. Change it in Quick Mask Options.

And don't forget to press Q again before applying an adjustment. Until you do, there's no selection, only the overlay.

It's one of the simplest tools in Paint by Zaweba and one of the most used. Once painting a selection becomes a habit, you'll find you reach for the lasso far less often.