Selecting objects with Object Selection in Paint
Drag round an object in Paint by Zaweba and Object Selection separates it with GrabCut and edge matting, then correct it with object and background strokes.
Drawing round an object by hand is slow, and the magic wand only works when the colours cooperate. Object Selection in Paint by Zaweba sits in between. You show it roughly where the object is, and it works out the edge for you, without any AI model.
Drag round the object
Drag a rectangle round the object, or draw a loose lasso round it. That is all the tool needs to start. It assumes the object is inside and most of what is outside belongs to the background, and from there it separates the two.
Make the rectangle snug but not tight. Leave a small margin of background all round so the tool can learn what the background looks like. For odd shaped objects, or when another object sits close by, the lasso is better because you can keep the neighbour out.
How it decides
Paint uses GrabCut, a well established method that models the colours of the object and the background and finds the boundary that best separates them. The edges are then refined by matting, which handles soft transitions such as hair, fur and slightly blurred outlines better than a hard cut would.
It is fast. A small object takes about 0.2 seconds. And no AI model is used, which fits with how Paint by Zaweba works: offline, no AI services, no telemetry.
Correcting the result
The first result is often close but not perfect. A patch of background with similar colours may have been included, or part of the object left out. Correct it with strokes.
Object strokes mark areas that belong to the object. Brush over a missed handle or a shadowed side and it is pulled in.
Background strokes mark areas that do not belong. Brush over a patch of table or wall that crept into the selection and it is pushed out.
A couple of short strokes usually does it. You do not need to paint the whole area, just enough to tell the tool what you meant.
What it is good at
Product photos for online shops, where a bottle, shoe or mug must be lifted from its background. Pets and people against fairly plain backgrounds. Objects you want to move, copy or recolour in a composite. Starting points for masks, so an adjustment affects only one object.
With the selection made, add a mask to hide the background, copy the object to a new layer, or use the contextual task bar's next steps such as Feather or Mask. For very fine hair, a refining step afterwards may still help.
When to reach for something else
When the object and background share colours closely, any colour based method struggles, and the Selection Brush or a lasso may be quicker. For a very simple object on a plain background, the Quick Selection tool or the magic wand may be faster. For whole scenes with many overlapping objects, select one object at a time.
Common pitfalls
Dragging the rectangle too tight, so part of the object is outside it. Painting many long correction strokes when a few short ones would do. Expecting it to separate two touching objects of the same colour; draw a lasso that excludes one of them instead.
Object Selection gives you a good selection in the time it takes to drag a box, and in Paint by Zaweba it does so entirely on your own computer.
