Using the Lens Correction Filter in Photoshop CS2
Dateline: April 5, 2005
The Lens Correction filter in Photoshop CS2 is truly amazing, being able to repair all kinds of distortions. Not only can it remedy the bulging created by a wide-angle lens and the weird distortion created by taking a photo too close to a subject – such as the bulging nose of a friend – but it can also straighten images taken at angles and make them appear as if they were shot straight on. To demonstrate, let’s take an image that suffers from many problems, such as the one below, and correct it.
Open an affected image and choose Filter > Distort > Lens Correction. The illustration below shows the filter’s dialog box. Notice the grid that assists us in lining things up.
The first job is to straighten the image, since it's impossible to fix all the other angles if the image is not straight first. Choose the Straighten tool from the left side of the dialog box, as shown below. Click and drag across the image to define the new horizon. Try to follow a horizontal line in the image, if there is one.
This image suffers from keystoning (it's narrower at the top than the bottom) so we'll adjust the Vertical Perspective value to make the top and bottom the same width. Adjusting the Horizontal Perspective appears to rotate the image through 3D space. What's really happening is that we're making one side narrower than the other to combat perspective problems. You can also change the Angle value to counter a diagonal distortion. The illustration shows the perspective repaired.
Notice how the image appears to bulge. Move the Remove Distortion slider to the left to "bulge out" and move to the right to "pinch in". This also works by choosing the Remove Distortion tool, which is the top-most icon on the left of the Lens Correction window. Once the tool is selected you can drag in the image, although I find that the slider provides more control. After adjusting the distortion, you may need to go back and again tweak the perspective. The Vertical Perspective has been readjusted in the example to compensate.
Finally, choose an Edge option:
Transparency: Produces transparent pixels outside of the distorted rectangle
Click OK to apply.
The before and after images below show the power of the Lens Correction filter. To finish off the effect, crop the image to suit your needs. As you can see, this really is a great tool for fixing distorted images.
This article is excerpted from How to Do Everything with Photoshop CS2 (McGraw-Hill) and is reprinted here by permission.
Colin Smith is the founder of photoshopcafe.com, a thriving Photoshop community. He is also a regular columnist for the NAPP members site and Planet Photoshop. He has authored and co-authored 6 books including New Masters of Photoshop, Foundation Photoshop, Photoshop Most Wanted, Photoshop Trade Secrets and Photoshop to Dreamweaver. He creates video tutorials that are available at www.photoshopcd.com. When he is not writing, Colin makes his crust as a freelance graphic designer. See his portfolio at www.pixeloverload.com.