Refers to systems that represent or encode or transmit information in a manner that is continuously variable, specifically not having to be rounded up or down to certain numeric values or being restricted to discrete pixel positions on a line. An analog picture reproducing system for example might reproduce any shade of red from a dark brown to a light pink while a non-analog system might only have twenty specific shades of browns, reds, and pinks to choose from. NTSC video is analog in the horizontal direction; details can occur anywhere along a scan line. It is not analog in the vertical direction; details that "fall between" two scan lines are lost or show up shifted slightly to fit on one of the scan lines.
