Lightroom - The Battle Of The Bulge

Some image distortion is inevitable in photography because of the way that lenses capture light. Lightroom is able to deal with it easily using its built-in lens lookup tables. Just head over to the Lens Corrections panel, and check the radio button labeled 'Enable Lens Corrections'. This enables the Lens Profile section of the panel.

If you are working with a mainstream and relatively modern camera, then chances are that Lightroom will automatically select the camera and lens profile needed to remove distortion. If not, then just select a near neighbor from the options available.

You can also choose to do things manually if you want, in which case just use the Amount section of the panel, and adjust the Distortion slider to get the desired effect.

By the way, at the same time as removing lens barreling effects, Lightroom also tackles any natural lens vignetting; usually noticeable as darkening at the edges of your image.