Jack – the generic term for a plug-in interface on digital equipment.
JPEG – an acronym for Joint Photographic Experts Group. This is a group of experts that were nominated to formulate international standards for image compression.
Judder – The visual phenomena on a television screen where the picture seems a little "jittery". This comes about because the normal frame rate for film is 24 frames per second which doesn't evenly divide into the 60 Hz refresh rate of a television screen. This leads to about 12 frames missing each second. To solve this manufacturers use a 3:2 pulldown algorithm to ensure that the slower frame rate of film will match the faster refresh rate of the television.The refresh rate for newer televisions is 120 Hertz which divides evenly into 24 making for a much clearer and sharper picture.