Lens profile

Almost all lenses suffer from aberrations, including distortion, chromatic aberration and vignetting. These are difficult to eliminate optically in the lens design, so software publishers are increasingly offering lens correction profiles to do this digitally. The software can identify the lens used from the image’s EXIF data and then find and apply the correct profile automatically.

Lens Modulation Optimizer (LMO)

A processing algorithm used by Fuji in some of its cameras to counteract the softening effects of diffraction at small lens apertures, and image softness at the edge of the frame. It seems likely the LMO is simply applying some intelligent sharpening.

Chromatic aberration

This is a lens aberration that produces colour fringing around the outlines of objects near the edges of the picture. It’s very hard to eradicate completely from lens designs without making them extremely complex or expensive, but it is possible to correct chromatic aberration using software and many cameras will now correct it automatically as they process the image.

Barrel distortion

This is where straight lines near the edge of the picture appear to bow outwards, and you see this a lot with zoom lenses at their wideangle setting. It’s most noticeable if the horizon is near the top or bottom of the picture. Barrel distortion is very difficult to eradicate completely from the lens design, but it can be fixed using software, and some cameras now have distortion correction built in. It’s one of a number of common lens aberrations. Telephoto lenses often show the opposite effect, ‘pincushion distortion’.

Aberrations

These are optical flaws produced by camera lenses and which are largely unavoidable except in the most expensive or the simplest lens designs. They include distortion, chromatic aberration (colour fringing), vignetting (corner shading) and edge softness.