Correcting Perspective Lens Distortion In Photoshop

Lens distortion is a potential problem for any photographer without access to a tilt shift lens, and not all of us have the ability or desire to dump a couple grand on one. There’s a lot of things that two grand could go towards besides a niche lens like a tilt shift. If you’re an architectural photographer, that is certainly a different story, but most people aren’t.

There are quite a few types of lens distortion, but this article is going to focus on perspective distortion. I’ve found, for photographers, lens distortion only becomes a problem once you discover what it is, and if you haven’t discovered it yet then I apologize in advance because now it will drive you nuts when you don’t want it! When I first started out, I had no idea that my lens distorted reality and therefore I never noticed it in my images. I remember when I first started posting photos to flickr when I was brand new photographer, I put up an image I took at a really old methodist church. I took the shot from the second floor balcony, which unknowingly to me at the time was probably the best place to shoot when trying to get straight lines all throughout your image. Unfortunately for me, I tilted the camera down a bit, which caused the vertical lines in the scene to lean in towards the center of the image.

When somebody tried to point this out to me, I was befuddled. I looked and looked at the image, but I couldn’t see what he was talking about. He just told me that the lines weren’t straight! I wasn’t looking at the lines in the scene in comparison to the edges of the frame, I was just looking at the lines themselves. They looked pretty dang straight to me, and I was getting pretty ticked off at this guy! Eventually, he told me to compare the lines in the scene to the outer edges of the framing itself and that’s when I had that first “aha” moment with lens distortion.

It’s important to note that lens distortion isn’t good or bad in and of itself. Like most things, it just depends on how and when you use it, and whether or not you meant to use it!

If you are unfamiliar with what I’m talking about, here are a few examples of intentional lens distortion…

Here’s a great example from a church. Notice how the pillars lean in toward the center of the frame? They don’t go straight up and down like they would in real life. This is pretty obvious distortion, but it works great in this image.

Here’s another example of a forest, displaying intentional lens distortion. The photographer pointed their lens straight up into the trees, so the distortion created a canopy of conifers that seem to close in on you. If you go to this forest and stand in this same spot, these trees would all be pointing straight up.

If you didn’t notice this before, I hope you’re having your own little “aha” moment right about now. Perhaps you noticed things like this in your subconscious, but never really thought about why an image looked the way it did. This type of lens distortion is most prevalent with wide angle lenses, and is caused by pointing the camera up or down relative to a subject. This is why if you look up and take a picture of a really tall building, or anything with vertical lines, it looks like it’s falling down on you. This isn’t necessarily bad, I think it certainly worked in the examples above, but it’s important to know how to fix it if that isn’t what you want in your final image. Sometimes, the composition demands straight, perfect lines.

Ok enough already, tell me how to fix it!

Ok ok, fine. There are numerous ways to fix lens distortion, but this tutorial will cover how to do it in Photoshop. I know for a fact you can do the same thing in Lightroom 3, and there are probably plug-ins out there that would allow for something like this in Aperture. I know, not everyone has Photoshop and I understand that, but you should seriously consider saving up for it if you don’t already own it. It’s an incredibly powerful program and I use it on a daily basis. Sure, it’s a bit pricy, but it’s highly worth it I promise!

Here’s an image from my library that we will use for an example…

Before we get started, if you are/were a fan of the series Prison Break, maybe this building looks familiar to you? Personally, I loved the show, but thought the last episode ruined everything. I just finished season 4 the other day and I was livid at the last couple minutes of that show! But I digress. You’ll notice in this shot that we definitely have some lens distortion to deal with. Take a look at the brick columns on the far left and right side, we want to use those columns as a guide to correct the distortion and make everything nice and straight. Here’s what you do in Photoshop…

If you can’t quite read what’s circle on the screen shot, just click the image to view it full size. You’ll notice that I numbered everything, so let’s go in order here…

1. Once your image is in Photoshop, select the crop tool from the left hand toolbar. You can also do this quickly by hitting the short cut “C.” Once selected, drag the crop tool over the entire image.
2. Once the crop overlay is covering the image, make sure that “Grid” is selected. This is a better option than the “Rule of Thirds” option in this case, as it will help you line up the distortion correction.
3. Here’s the little box that a lot of people don’t know about! Without this box selected, you can only make standard crops by dragging the corners or sides up and down. With this box selected, you can now drag the corners in to correct perspective lens distortion!
4. As you can see here, I grabbed each top corner in and used the far right and left columns as a guide to make the grid line up with the angle of the columns. That’s it! Photoshop will do the rest of the work from here, so once you have the crop overlay where you want it, just hit enter and see what happens.

Here is the final result…

Conclusion

As you can see, the columns around the doors are now perfectly straight up and down. You might think it unfortunate that I lost the columns on the far right and left, but here’s a secret: I knew when taking this shot that I’d need to do some lens correction on it. Therefore, I took a few steps back and placed those far columns just inside the frame to act as a guide later in Photoshop. Once you learn tricks like this, you can plan ahead later on.

If you have any questions about this tip, be sure to leave a comment. If you know of a plug-in that can do this in other programs like Aperture, be sure to let us know that as well!

Finally, I’m always looking for cool, fellow photographers to connect with on Twitter, so be sure to follow me (@jamesdbrandon) if you don’t already. Cheers, and happy shooting!