Adobe released recently a number of updates for Photoshop CC, but the one that was most interesting for me was the new Perspective Warp feature. This is a tool that allows you to modify the perspective of elements within a picture while not impacting other parts of the picture. A common situation where this presents itself is in architectural photography where a building needs perspective correction.
For example, let’s say that you were photographing a building with a wide-angle lens and needed to point the camera upwards in order to get the entire structure in the frame. Angling a lens upward causes the scene to keystone or look like everything is leaning backward. The vertical lines of the building don’t appear straight up and down, rather they render as converging lines pointed to the sky.
There are a couple of ways to prevent keystoning in the field. One solution is to use a tilt and shift lens such as the Manual Focus 24mm f/3.5 PC-E Nikkor perspective control lens.
The downside to this beautiful lens is it isn’t cheap at $2,000. Another solution in the field is to shoot with the camera perfectly level. Keeping the camera level in all three axes helps prevent the keystoning distortion caused by tilting the lens. Sometime though this isn’t possible because you are positioned too close to the object and the lens isn’t wide enough to get it all in.
If you don’t have a perspective control lens or if you aren’t able to shoot level, then the only option available for you is to fix the perspective problem later in software. There are quite a few automated software solutions designed to help correct perspective distortion, such as Adobe Camera RAW, Lightroom 5 Lens Corrections and DxO Optics Pro 9. Each of these solutions does a good job, but sometimes it is best to do perspective adjustments manually so you have more control over how the image is affected.
Any time you do a perspective adjustment to an image, you are forced to move pixels around and this often requires you to have to re-crop the image after the adjustment. Using an automated solution like Lightroom 5 Lens Corrections means you’ll be limited in terms of what you keep and what you crop. These programs often automatically determine the cropped area and don’t allow you to further warp and bend pixels.
Using the Perspective Warp tool in Photoshop however, allows you to manually control the amount of the adjustment while warping pixels to best fit your own vision. Fixing perspective problems this way in Photoshop takes a bit longer, but can result in a better final result if you know what you are doing.
In the example shown here, I used a photograph of a row of buildings that I recently shot in Iceland. For this image, I used a Nikon D600 with a Nikon 14-24mm lens. I needed to angle the lens upward in order to capture the top of the closest building, so as explained above, this caused the keystoning effect you see in the first figure above.
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