blocking artifacts

(redirected from macroblocking)

blocking artifacts

A distortion that appears in compressed video material as abnormally large pixel blocks. Also called "macroblocking," it occurs when the encoder cannot keep up with the allocated bandwidth. It is especially visible with fast motion sequences or quick scene changes.

Video uses lossy compression, and the higher the compression rate, the more content is removed. At decompression, the output of certain decoded blocks makes surrounding pixels appear averaged together and look like larger blocks. As TVs get larger, blocking and other artifacts become more noticeable. See artifact and pixelated.


Before and After
The lines at the edge of the original frame are used to point to the blocking artifacts, which are removed with Algolith's MPEG Noise Reduction system. Both images are enlarged to show details. (Image courtesy of Algolith inc., www.algolith.com)
References in periodicals archive ?
Terms like jitter, latency and macroblocking quickly became part of the TV lexicon.
The Examine tools, which are shown in Figure 8, incorporate macroblocking detection, which is the primary video-quality metric besides PSNR, as well as detecting curtains, black frames, and periods of silence in the audio.
Most of the time, people called in to report that they had macroblocking, where the picture goes apart and then back together," she said.
Top three issues are video freeze, macroblocking and video blackout