Digital Focus: Fix Perspective in Your Photos

Feature: Correct Your Perspective

Have you ever noticed how photographs of buildings tend to come out with walls that curve or stand at odd angles? It's ugly, to be sure, but it's a common effect nonetheless. When you look at things like tall buildings, your brain does a lot of "corrections" behind the scenes to make them look right in real life. But your camera doesn't have the same sort of mechanisms, and so your pictures can suffer from perspective problems.

In fact, your pictures will exhibit something known as "perspective distortion" whenever you hold the camera at an odd angle, not parallel to the ground. In the film world, there are special camera lenses made for this kind of photograph. Professional photographers have to spend a lot of time setting up architecture shots to eliminate perspective distortion--thus ensuring that parallel lines will stay parallel in the photograph--before they even press the shutter release. Thankfully, in the digital world, it's easy to correct for this in an image editor like Paint Shop Pro 8 or Adobe Photoshop Elements.

Suppose you've taken a photo of the Times Square area of Manhattan from a hotel-room window. Since the camera was pointed down, the buildings are distorted: The buildings bend inward at the top of the photo and the building on the right has jagged vertical lines running up the front of it.

Using Paint Shop Pro

To fix this image in Paint Shop Pro 8, you can use the new Perspective Correction tool. (If you're using an older version of Paint Shop Pro, or another image editor, be patient: I'll tell you about another way to do this later.) Select it from the tool palette--it's the second tool from the top, but you might have to choose it from the drop-down menu, since PSP now packs multiple tools into each space.

You should see a box appear in the image. Use the mouse to align the top of the box over the building on the right (the one with the most apparent distortion), and position the box so it outlines the front of the building.

When you're done selecting the building, click the OK check box at the top of the screen. PSP corrects the distortions throughout the image. To finish up, you simply need to crop the image to a more traditional rectangular shape (by cropping out the white portions) and save it.

Or Do It by Hand

What if you're using an image editor that doesn't have a nifty Perspective Correction tool? You can still correct the image, but you'll have to do it yourself. If you use Adobe Photoshop Elements, for instance, you'd open the image and then create a new layer. To do that, double-click the layer's name in the Layers Palette (which usually opens in the lower right corner of the screen). Now choose Image, Transform, Distort from the menu, and you'll see a box appear at the edges of the image window.

At this point, it's easiest to enlarge the image window so you can better see the Distort box. Maximize the image. Now grab the top left and right corners of the box and drag them away from the image, stretching the top of the picture. You'll have to play with it a bit, but you should be able to correct almost all of the distortion in the buildings. When everything looks about right, accept the changes and crop the image back to a rectangle. You're done!

Finally, if you still use Paint Shop Pro 7, you can make a similar correction. Select Effects, Geometric Effects, Perspective--Vertical. Move the slider until the photo looks the way you want it to in the preview box, then click OK to implement the change.