Digital Photographer's Software Guide - Bertemes - Net

In digital photography, noise is an unwanted pattern of pixels, usually a speckle pattern
of random pixels, especially visible in images taken in low-light conditions at a high ISO
setting. Camera manufacturers have been successful in keeping it to a minimum, especially
Canon with its full-frame DSLRs. However, noise can still be obtrusive in images from
cameras using smaller format sensors and often needs to be treated in post-processing.
Software typically begins by analyzing the individual image, creating a “noise profile”
to indicate just what type of noise is affecting picture quality. For example, there is the
standard “read-out” noise generated by the amplification of the signal, but there is also
“thermal noise” caused by electrons leaking from the image sensor. Scanned images from
film-based photographs may show “grain,” which is often considered to be more attractive
than digital noise but may still need to be eliminated from some pictures. Film grain
shows up clearly in bright areas as well in shadows, but digital noise is more apparent
in the dark parts of the image. Any degree of underexposure will make high-ISO noise
worse in a digital picture.
Software Solutions
17
Noise Reduction
Clever software goes a long way toward banishing noise from digital images, although
theoretically there is always a trade-off in using it. In practice, however, software such
as Neat Image from ABSoft, Noise Ninja from PictureCode, and Image Doctor from
Alien Skin can restore an otherwise unusable picture to publication quality.
Noise reduction software is not very expensive but it can make a dramatic improvement
to the image. The best packages are “edge aware,” meaning that they can detect and preserve
the edges of objects depicted in the photograph. Every developer promises to
“reduce noise while preserving fine detail,” but some are more successful at this than