Frequently we make images with wide-angle lenses that suffer from distortion. This distortion is caused when we point our camera up or down, causing vertical lines to bend. There are several ways to correct this distortion in the digital darkroom. Lightroom has distortion correction built in to the Develop module on the Lens Correction panel with the Upright tool. This option works well in most cases and is the easiest to use, but in examples of extreme distortion may fall short of expectations.
In Photoshop, there are three tools that can be used to correct distortion: Transform, found under the Edit menu, and Adaptive Wide Angle and Lens Correction, found under the Filters menu. Of these three tools, Adaptive Wide Angle is best suited for correcting the extremes of wide-angle lenses.
On a trip to India, I had to decide which lens to take: my 17mm tilt/shift (my favorite wide-angle lens) or my 14mm wide angle. The tilt/shift lens eliminates all the perspective problems but is not really a hand-holding type lens. It works best when you are on a tripod, since you need your hands free to physically move the knobs on the lens to invoke the tilts and shifts. I knew that on this trip I would not be allowed to use a tripod at most of the monuments, shrines, temples and forts we would be visiting, so I chose to take the Canon EF 14mm f/2.8L lens instead.
It turned out to be the correct decision, but when I used the 14mm, I could see that there were many instances where my perspective was being warped by the lens distortion, and I would have to correct the images after the fact. Tip: When you see your lens is distorting and you know you are going to fix this digitally, make sure you give yourself a little extra room in the composition, because you usually end up cropping some of your scene.
In this example, taken at the Taj Mahal, the minaret tower on the left and the Taj on the right are both severely distorted (Figure 1, above). I wish I had composed with a bit more room on both sides. I do want to crop out the man on the left, but I would like to have more room to crop on the right.
When I first opened this image in Lightroom—my standard starting place for processing my images—my inclination was to go to the Transform panel and select the Guided option to correct the distortion. I have used this tool in many instances where it performed well and was all I needed to fix my images.
To use the Guided Transform feature, you draw lines following the distorted vertical or horizontal lines that need to be fix, and the transform function straightens the lines. When using this tool, you need to draw at least two lines before the tool will work.
Figure 2 shows the Transform panel where I selected Guided mode, as well as the four lines I drew along edges I want to straighten. As you can see in the result, the building on the right looks really good, and the minaret is fairly straight. But notice the spire on the top of the Taj Mahal on the right is very soft, and the mosque (the red building in the background) is not level. Also notice the image is cropped at both top and bottom. While this is a big improvement and will satisfy most people, it is still not perfect and not of the quality I would have achieved with my tilt/shift lens. So, I was looking for a better way to fix it.
When I take this image into the Free Transform tool in Photoshop (Figure 3), I get a result similar to what I received from the Upright Tool in Lightroom. It is a big improvement, but you can see on the minaret tower the horizontal lines are not horizontal.
I got the best results using Photoshop’s Adaptive Wide Angle filter. To access this tool, open your image in Photoshop, open the Filter menu and go down to Adaptive Wide Angle. This will open the image in a dialog box. I suggest working in the Auto mode unless you have a true spherical fisheye lens.
To use the tool, simply take your cursor and drag it along any distorted line you wish to correct. In this image, I ended up drawing eight lines to fix the perspective problems. I drew my first line along the right edge of the minaret tower (Figure 4). When you let go of the cursor, you get the constraint line shown in Figure 5.
On the large gray circle of the constraint line there are two white circles, which serve as handles. When you hover the cursor over the handles, the cursor changes to a curved double-ended arrow. Once you see the arrow, click your mouse, and you will see the current angle of the line appear. Simply drag the cursor to set the appropriate angle of the line. In this case, it was a vertical line, so I needed to drag to 90 degrees (Figure 6). If it is a horizontal line, you want to drag to 0 (zero). This will instantly straighten your line.
To straighten all the lines in the image, I added a second constraint line to the left side of the minaret tower, a third constraint line to the building on the right, a fourth constraint line to tiles on the ground, a fifth constraint line to the left edge of the building on the right, a sixth constraint line to the small wall in the back, a seventh constraint line to the roof top of the building on the right, and an eighth line to straighten the little point on top of the minaret (Figure 7).
When you are finished, you will have some areas of transparency where the image crops and stretches. At this point, you can choose to crop and/or use Content Aware Fill to fill in the areas. I did a combination of both. Figure 8 shows the final result.
As I mentioned, my first choice would have been to photograph this scene with my tilt/shift lens, because I would have been able to control all distortion with the lens, and I would have been able to accurately compose my image without the need for cropping. But not everybody owns a tilt/shift lens or, as in this case, has the opportunity to use it properly. That’s where Adaptive Wide Angle can help you achieve perfect perspective with any wide-angle lens you use.
See more of Lewis Kemper’s work at lewiskemper.com.