Mosquito noise is a type of distortion sometimes seen around the edges of moving objects in MPEG and other video frames that are compressed with the discrete cosine transform (DCT). It is characterized by moving artifacts around edges and/or by blotchy patterns superimposed over the objects, resembling a mosquito flying around a person's head and shoulders.

Mosquito noise usually occurs during decompression when the decoding engine has to approximate the discarded data by inverting the transform model. The mosquito noise appears as random aliasing in these areas and requires sophisticated detection circuits to eliminate it.

Example of Mosquito Noise:

As TVs get larger, mosquito noise and other artifacts become more noticeable. Algogear™ series Video Noise Reduction cards (VNR-1000-SD and VNR-1000-HD) or Algolith Noise Reduction IP technology are highly effective for both pre-processing and post-processing DCT-based compression artifacts. Algolith Mosquito Noise Reduction technology uses both temporal recursive noise and mosquito noise reduction techniques which are designed to isolate and remove artifacts while maintaining the integrity of the detail in the image.

See image before and after Algolith's video processing

(click to enlarge picture).