Chroma Noise

    Chroma noise affects areas of colour in the image. Instead of being clean, even areas of colour, chroma noise makes colours look grainy due to random noise being inserted into the colour signal. Chroma noise seems to particularly affect blue, although it can potentially be seen in any large expanse of a single colour. Chroma noise is pretty much exclusively an artefact of analogue video processing, and it is very rare to see it in modern, all-digital transfers. Increased MPEG macro-blocking artefacts are a potential side-effect of chroma noise, as the MPEG encoder attempts to encode the extra spurious random noise, leaving less bits for actual picture information..

Classic Albums Series 2: Steely Dan-Aja 3:30

Note the uneven and noisy background - noise not present at the live performance that this image was taken from.