Editing in perspective with Perspective Planes
Filter > Perspective Planes in Paint by Zaweba lets you define planes in a photo, then clone, paint and place images in correct perspective.
Cloning a brick wall to hide a sign works well when the wall faces you square on. When it recedes into the distance, ordinary cloning copies bricks at the wrong size and the fix stands out. Filter > Perspective Planes in Paint by Zaweba solves this by letting you describe the flat surfaces in the photo first, so cloning, painting and placing images follow their perspective.
Defining planes
Start by defining a plane with four corners. Click the corners of something you know is rectangular in real life: a window, a tile, a paving slab, the face of a box. The plane takes the shape that rectangle has in the photo.
From the way the plane's edges converge, Perspective Planes works out the vanishing points and derives the focal length of the lens. That is what lets it treat everything you do on the plane as though it sits on that real surface.
Planes can be extended at any angle. Once the front wall is defined, you can pull out a plane for the side wall or the ground, sharing an edge with the first. The new plane keeps the same geometry, so a corner of a building or the join between floor and wall is handled correctly.
Lay out all the surfaces you plan to work on before you start editing.
Cloning and painting in perspective
Clone on a plane and the source is scaled and angled to match where you paint. Copy bricks from near the camera to the far end of the wall and they shrink as they go, keeping the rows lined up. This makes it practical to remove objects from walls, floors, pavements and other receding surfaces.
Brushing on a plane works the same way. A stroke near the camera is larger than the same stroke at the far end. That is useful for painting stripes on a road, adding texture to a floor or touching up a receding fence.
Placing images
You can place images on a plane too. Put a logo, poster or sign onto a wall and it takes on the wall's perspective. Move it along and it gets smaller as it goes further away. This is the quickest way to make a mock-up: artwork on a shop front, a mural on a building side, a label on a box.
Where the result goes
You can send the result to a new layer or the current one. A new layer is almost always the better choice. It keeps your original photo untouched, lets you lower opacity or add a mask afterwards, and makes it easy to start again.
Removing a sign from a wall
To remove a for-sale sign from a brick wall: open Perspective Planes, define a plane on the wall using the corners of a few bricks or a window, extend it as far as the wall goes, and choose a new layer as the output. Clone clean bricks from beside the sign over it. Leave the filter and check the join at normal zoom, then soften any visible edge with a mask.
Avoiding a bad plane
Most problems start with a bad plane. If cloned bricks do not line up, the four corners are probably not quite on a true rectangle. Redefine the plane using a larger rectangular feature, since bigger features give more accurate geometry. Also watch out for surfaces that are not flat, such as a curved wall, which no plane can describe properly.
Perspective Planes takes a minute of set-up and then makes perspective editing in Paint by Zaweba feel straightforward.
