That’s the source of the keystoning. In the photograph of the same church below, I corrected the distortion in Photoshop. If you use a perspective control lens, which is specifically designed to correct keystoning in-camera, post-processing isn’t necessary to address this issue. Most photographers don’t carry such a lens because they are expensive and heavy, so here are the steps required to make the vertical lines vertical in Photoshop: 1. Open the image to be corrected and choose Select > all. 2. Choose the pulldown menu command Edit > transform > distort. 3. Grab the lower right or lower left corner of the image and pull it to enlarge the working
area. See the screen capture on the next page. The green arrow shows the place where you can drag to expand the area around the photograph. Once expanded, a black frame will surround the image. 4. Immediately around the picture area itself is a box with handles. This was created from performing Step 2. The handles are shown by the blue arrows, same screen capture. When you pull the top left handle to the left and the top right handle to the right, the vertical lines of the subject which were originally skewed inward now become straightened. As you can see from the screen capture, the handles don’t have to be pulled symmetrically. In fact, in most cases they will appear asymmetrical as you work to align the vertical lines with the left and right sides of the picture frame.
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