Cropping With Perspective

Many of the best Photoshop tools are slightly hidden, requiring users to dig a little to find them. Take the Perspective Crop tool, for instance. It’s buried under the Crop Tool on the toolbar, and to find it, you simply click and hold on the Crop Tool to reveal a popup menu containing it. Click the second icon and the Perspective Crop tool is activated.

Now that you’ve got it locked and loaded, what exactly does it do? Unlike the traditional crop tool, which is constrained to cropping rectangular shapes containing four right angles, the Perspective Crop tool can be used to accomplish two adjustments in one. Beyond simply cropping the image area, it will also transform the perspective. This can be done to correct for the distortion that occurs when photographing a structure from an angle, for instance, or it could be used to introduce perspective distortion for creative effect.

To use it, with the tool active as outlined above, click and drag to draw a cropping rectangle anywhere in the frame. Then corner by corner, click and drag each corner to fit a real-life rectangle that has been distorted in the photograph. A window is a common choice, for instance, or an entire building’s façade. In this way, the tool works similarly to the Vanishing Point filter, which allows users to create a plane that permits perspective matching edits to the image. But with the Perspective Crop tool, once the four corners of the crop have been established, no matter the quadrilateral it forms, when you double-click to crop Photoshop will automatically render that area to a rectangle—no matter whether the selection featured right angles or not. The result, of course, is that a rectangular image element, distorted during photographing, is now rendered correctly once again as a rectangle.

In practice, this distortion correction is especially useful for adjusting subtle off-axis planes that the photographer would have preferred to photograph at a 90-degree angle. It’s a great way to crop and transform a scene so that its perspective appears straight and square.

Beyond this incredibly useful distortion correction effect, the Perspective Crop tool can also be helpful for situations in which an image element is to be pasted into such a distorted rectangle, but in which the exact proportions are difficult to measure. For instance, if a computer display photographed at an angle is due to have a screenshot pasted in, one way to match the proportion accurately is to start by using the perspective crop tool to crop a copy of the empty computer screen. Once it’s rendered into a rectangle, users can measure its proportion to determine whether it’s a 4 x 6, 5 x 7 or 8 x 10 as the case may be. Then the original image can be cropped to more closely match those proportions so that when it’s pasted into place and transformed to match the perspective, the contents of the screen won’t be disproportionally distorted. It’s a highly specific use but one that’s incredibly useful when proportions matter.

The next time you need to correct for the distortion caused by photographing a subject at an angle, consider using the Perspective Crop tool for a simple and effective fix.

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