Match Perspectives When Compositing

When compositing two images together in Photoshop, one of the most accurate ways to do it is to start by photographing the objects with the same focal length lens, from the same distance and camera angle. This way the perspectives will match.

But often we’re tasked with compositing two images that weren’t shot with the same perspective. Getting such mismatched images to blend seamlessly can be a real challenge. This is especially common when adding something photographed square to the camera to a scene or element that was photographed at an angle. When adding a computer screenshot to a tablet display, for instance, or when adding a 2D graphic to a photograph of a very three-dimensional object. Thankfully, Photoshop offers a couple of easy and effective ways for photographers to match perspectives when compositing.

Free Transform

Perhaps the simplest approach to make a pasted object fit in with its surroundings is to use Photoshop’s Free Transform tool. This can be found under the Edit menu or via the Command-T (or CTRL-T) keyboard shortcut.

With an image element pasted onto its own layer and the Free Transform tool activated, clicking and dragging on any corner of the object will enlarge it or shrink it proportionally. But by holding the Command key (or Control key on Windows) and clicking and dragging on any corner, the object can be pulled and stretched and twisted with each corner independent of the others.

match perspectives when compositing

In this way, Command-clicking and dragging on the corners of a square pasted object until they align with the corners of a perspective-shifted square in the background image will quickly make the perspectives close to matching. For pasting a screenshot into a laptop display, for instance, this Free Transform technique works great. Because this approach is done by eye, however, it’s not going to guarantee accuracy when scale is especially important. For this, the next tool is ideal, but Free Transform is still a very easy and effective approach in its own right.

Vanishing Point

A more scientific approach to matching perspectives is to use Photoshop’s Vanishing Point filter. With Vanishing Point, the photographer can click on four corners of a real-life rectangle in an image—which, based on the angle at which it was photographed, now appears as a quadrilateral whose sides may no longer be parallel—and map the perspective so that a new element may be pasted accurately. It’s a pretty impressive technical feat, but it’s not difficult to implement.

Simply open the background image in Photoshop, followed by the image of the object to be copied and pasted into the scene. Then select and copy that object. (In practice, this could be a building exterior photograph as the background image and an image of a door to be composited onto it, as in the slightly absurd example shown here.)

With the door cut out and copied, click to create a new layer of the background image on which to work. Next, look for the Vanishing Point heading under the Filter menu to open the Vanishing Point tool.

match perspectives when compositing

From here, choose the Create Plane tool (second from the top on the left-side toolbar, or the C key) and then click to establish the first corner of the plane. Look for a real life in the image—such as the top left corner of the wall or the top left corner of a window therein. Next, click the top right corner, the bottom right corner and finally the bottom left corner. This has now established a plane that vanishing point will use to alter the perspective of any element pasted into it—such as the painting we selected and copied in an earlier step. 

Click and drag on the sides of the plane map to expand it enough so that the image element can be pasted into it in full. Then click Command-V to paste the object (in this case the blue door) into the scene.

Click and drag to move it into the established plane and watch as Photoshop automatically alters its perspective. Click OK to render the edit and find the modified object on its own new layer. From here, scale adjustments and fine-tuning can be done with the aforementioned Free Transform tool, and layer masking can be used to help blend the object more seamlessly into the background.

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