If you like taking photos of architecture and cityscapes, you’ve probably noticed that if you angle your camera up or down, the vertical lines of buildings tend to converge. Sometimes (not always), we want them to stay straight. And if you don’t have a tilt-shift lens, then you need to do that in post-processing. Here’s how to do it in Lightroom (the process is the same in Photoshop and Camera Raw) with the Transform tool.
See the example below. On the left side is the original image, with the background building leaning backward. What I wanted is to have the lines vertical to emphasize the curves of the Petersen Museum (Los Angeles) in the foreground (right).
To do that, head over to the Develop Module in Lightroom. On the right, find the Transform Panel. For our purposes, we’ll focus on the top of the panel (ignore the sliders below unless you want to do things manually). First, you have these 6 buttons (see below). You can play with them to see if they work. Auto will attempt to guess what you want to straighten. Level will correct horizontal lines. Vertical will correct, well, vertical lines. Full will do both.
More often than not, it doesn’t work. Or it’s just a little bit off. This is why my favorite mode is Guided. It allows you to tell Lightroom exactly which lines you want to straighten. You do that by clicking the button at the top left of the panel (see below).
Once you’ve clicked on the button, you can draw the guides to tell Lightroom what to straighten. Click and drag along a line to draw a guide. You can draw up to 2 vertical guides and up to 2 horizontal guides (for a maximum of 4). In the example below, I drew two vertical guides to straighten the background.I recommend drawing guides close to the edges of the image. It works significantly better than if you put the two guides in the middle of the image.
Don’t forget that when you straighten an image like this, you will lose parts of the image. There’s no way around it, so anticipate and shoot a little wider if you know you’ll want to straighten the verticals.
Another way you can use the guides is to correct symmetrical images. The image below (from Chicago) is slightly off: it leans to the right but a simple rotation wasn’t enough.
Here’s another example with a cityscape from New York City. I used the Transform tool to make sure my “frame” was perfectly straight.