Artifacts and Pixelation - what exactly are they? (1 Viewer)

[Dick Garwood]

I've seen "artifacts and pixelation" used quite a bit on this forum but I do not recall seeing an explanation of what they are and exactly what they look like. Please a good explanation. Thanks.

 

[Jeremy Allin]

Artifacts, as I understand it, are a by-product of compression. DVDs with many extras must have the movie compressed more heavily therefore increasing the likeihood of compression artifacts. I like to refer to them as 'dancing squares'.

 

[Allan Jayne]

Artifacts -- Distortions or incorrect things occurring in the picture or sound due to less than perfect studio production, storage, processing, or reception. Example in analog video: Dot crawl around the edges where two contrasting colors meet, because the comb filter was mediocre.
Perhaps you have seen in a movie or newscast the hiding for privacy's or censoring's sake of a person's face with a checkerboard pattern of different shades of colors. This is an example of pixellation (sp?) but in this case it is supposed to be that way and is therefore not an artifact. Often pixellation as an artifact occurs during the playing of DVD's because there is too much processing, such as in a tremendous amount of subject motion, and some brands of players have electronics and built in computer that can't keep up. Because DVD and HDTV involve lots of data compression, lots of processing power is needed.
Video hints:
http://members.aol.com/ajaynejr/video.htm