Editing Color television (section)

====Compatible color====
<!-- Courtesy note per [[WP:RSECT]]: [[Compatible color]] and [[Color compatible]] redirect here -->
While the FCC was holding its JTAC meetings, development was taking place on a number of systems allowing true simultaneous color broadcasts, "dot-sequential color systems". Unlike the hybrid systems, dot-sequential televisions used a signal very similar to existing black-and-white broadcasts, with the intensity of every dot on the screen being sent in succession.

In 1938 [[Georges Valensi]] demonstrated an encoding scheme that would allow color broadcasts to be encoded so they could be picked up on existing black-and-white sets as well. In his system the output of the three camera tubes were re-combined to produce a single "[[Luma (video)|luminance]]" value that was very similar to a monochrome signal and could be broadcast on the existing VHF frequencies. The color information was encoded in a separate "[[chrominance]]" signal, consisting of two separate signals, the original blue signal minus the luminance (B'–Y'), and red-luma (R'–Y'). These signals could then be broadcast separately on a different frequency; a monochrome set would tune in only the luminance signal on the VHF band, while color televisions would tune in both the luminance and chrominance on two different frequencies, and apply the reverse transforms to retrieve the original RGB signal. The downside to this approach is that it required a major boost in bandwidth use, something the FCC was interested in avoiding.

RCA used Valensi's concept as the basis of all of its developments, believing it to be the only proper solution to the broadcast problem. However, RCA's early sets using mirrors and other projection systems all suffered from image and color quality problems, and were easily bested by CBS's hybrid system. But solutions to these problems were in the pipeline, and RCA in particular was investing massive sums (later estimated at $100&nbsp;million) to develop a usable dot-sequential tube. RCA was beaten to the punch by the [[Geer tube]], which used three B&W tubes aimed at different faces of colored pyramids to produce a color image. All-electronic systems included the [[Chromatron]], [[Penetron]] and [[beam-index tube]] that were being developed by various companies. While investigating all of these, RCA's teams quickly started focusing on the [[shadow mask]] system.

In July 1938 the [[shadow mask]] color television was patented by [[Werner Flechsig]] (1900–1981) in Germany, and was demonstrated at the [[IFA Berlin|International radio exhibition Berlin]] in 1939. Most CRT color televisions used today are based on this technology. His solution to the problem of focusing the electron guns on the tiny colored dots was one of brute-force; a metal sheet with holes punched in it allowed the beams to reach the screen only when they were properly aligned over the dots. Three separate guns were aimed at the holes from slightly different angles, and when their beams passed through the holes the angles caused them to separate again and hit the individual spots a short distance away on the back of the screen. The downside to this approach was that the mask cut off the vast majority of the beam energy, allowing it to hit the screen only 15% of the time, requiring a massive increase in beam power to produce acceptable image brightness.

The first publicly announced network demonstration of a program using a "compatible color" system was an episode of NBC's [[Kukla, Fran and Ollie]] on 10 October 1949,<ref>[https://www.youtube.com/watch?v=wmBKjL00BSA "Kukla, Fran and Ollie" broadcast]</ref> viewable in color only at the FCC. It did not receive FCC approval.

In spite of these problems in both the broadcast and display systems, RCA pressed ahead with development and was ready for a second assault on the standards by 1950.