BE A PUPPETEER

Α rather unusual title, but rest assured that we have no intention of making you one.

- Ashok Kandimalla

This is a panorama image created handheld. Consequently, the sides do not form a proper rectangle. This can be rectified simply by cropping. More troublesome is the curved edge of the land as shown by the arrow marks. Our aim is to rectify this.

Rather, we want to show you how to solve a common photographic problem using a Photoshop tool. Let us see what the issue is and how Photoshop can be used to eliminate it.

Reproduction of a hypothetical distortion-less lens

Ideally, when you photograph a straight line, it should again be reproduced in your captured image as a straight line. If there is any curvature that was originally not there in the subject, then we say that the image exhibits distortion. There are a few types of this phenomenon, but here, we are concerned about barrel distortion in which the straight lines bulge outwards like a barrel (Pictures 1 and 2). This occurs in almost all wide-angle lenses, but of late, you are seeing less of it due to advances in software technology. Every modern lens supplies its characteristics through what is called a 'lens profile' and most software (including Lightroom and Photoshop) can read this profile and apply the needed correction in post-processing even without any user intervention. If you are using a lens whose profile is not available, then you can also manually correct the distortion with various tools. One such tool is the Adaptive Wide Angle filter in Photoshop.

Barrel distortion.

In this article, we will concentrate more on the distortion that arises when you create a panorama from multiple images. Let us look at this in more detail, starting with a brief description of the steps needed to create a panorama.