The system used the existing black and white signal but with the addition of a component intended only for television receivers designed to show color.
By careful application this 'colored' signal was ignored by ordinary TV sets and had negligible effect on the appearance of the black and white image.
This meant that color programs were viewable on the many existing black and white receivers which fulfilled a requirement for 'compatibility' desired by the television industry.
This process was by the standards of the day quite complex and demanded accurate control of all the various parameters involved if an acceptable color image was to be achieved.
The Second NTSC Standard (525/30, 1941 and later) anticipated that the extant monochrome TV system would eventually incorporate a provision for monochrome-compatible color television.
Central to this revised standard was a mandate for an information stream, at the transmitter, and broadcast to TV sets (receivers), which was independent of whether the signal was monochrome (already in existence since 1941) or color (adopted in 1953).
However, the obvious high cost of R-, G- and B-signal management within a large-market TV station, with separate studio and transmitter sites (sources and destinations separated by perhaps one to tens of miles), or particularly within a TV network, with geographically widely separated sources and destinations (sources and destinations separated by perhaps hundreds to thousands of miles), resulted in adoption of RCA's "one Colorplexer per color source" recommendation almost universally, and particularly after Ampex's introduction of color videotape in 1958 (which was never a component system at all, but was always inherently a composite system), and Ampex's (and, later, RCA's) color videotape systems became essential subsystems of multi-time-zone (national, or, indeed, international) network color TV distribution and transmission.
Edge enhancement is now a part of many electronically based color systems, but in "Three-Strip" Technicolor's day, it was accomplished photographically from the G image, the sharpest of the three.