when did the first color tv go on sale
Color television While the CBS color broadcasting schedule gradually expanded to twelve hours per week (but never into prime time),[35] and the color network expanded to eleven affiliates as far west as Chicago,[36] its commercial success was doomed by the lack of color receivers necessary to watch the programs, the refusal of television manufacturers to create adapter mechanisms for their existing black-and-white sets,[37] and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. CBS had bought a television manufacturer in April,[38] and in September 1951, production began on the only CBS-Columbia color television model, with the first color sets reaching retail stores on September 28.[39][40] But it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS discontinued its color television system on October 20, 1951, ostensibly by request of the National Production Authority for the duration of the Korean War, and bought back all the CBS color sets it could to prevent lawsuits by disappointed customers.[41][42] RCA chairman David Sarnoff later charged that the NPA's order had come "out of a situation artificially created by one company to solve its own perplexing problems" because CBS had been unsuccessful in its color venture.[43]
Chroma key Green is used as a backdrop for TV and electronic cinematography more than any other colour because television weathermen tended to wear blue suits. When chroma keying first came into use in television production, the blue screen that was then the norm in the movie industry was used out of habit, until other practical considerations caused the television industry to move from blue to green screens. Broadcast quality color television cameras use separate red, green and blue image sensors, and early analog TV chroma keyers required RGB component video to work reliably. From a technological perspective it was equally possible to use the blue or green channel, but because blue clothing was an ongoing challenge, the green screen came into common use. Newscasters sometimes forget the chroma key dress code, and when the key is applied to clothing of the same color as the background, the person would seem to disappear into the key. Because green clothing is less common than blue, it soon became apparent that it was easier to use a green matte screen than it was to constantly police the clothing choices of on-air talent. Also, because the human eye is more sensitive to green wavelengths, which lie in the middle of the visible light spectrum, the green analog video channel typically carried more signal strength, giving a better signal to noise ratio compared to the other component video channels, so green screen keys could produce the cleanest key. In the digital television and cinema age, much of the tweaking that was required to make a good quality key has been automated. However, the one constant that remains is some level of color coordination to keep foreground subjects from being keyed out.[7]