A Note about “Lines”
In digital video the image is made up of a defined grid of picture elements (or “pixels”). Analogue video isn’t. It is constructed by a defined number of horizontal rows, or “lines,” of varying brightness of an electron beam. But not every line is used to encode the image. Some lines from the top and bottom of the image are blank to form a “vertical blanking interval.” This is to allow the electronics in old TVs a bit of time to move the electron beam to the start position before the next image is received.
Baird
1930 – 30 x 70
The first TV sets ever sold to members of the public were of the design of John Logie Baird. Sold to fund his research, buyers were treated to experimental broadcasts made by him and the BBC from 1929 to 1935. His system used rotating wheels with a spiral of holes in it to scan and reconstruct an image. Because of this, its lines were vertical.
The actual screen on many early TVs were small. The Baird Televisor here had a screen half the size of a business card. It was common they had a magnifying lens in front of it to make the image bigger.
If you look closer, you’ll see that the end three lines on each side of this screen are a bit futher apart than the rest. This is to make the image appear wider.
Baird chose a 3:7 aspect ratio because the low resolution only allowed enough room for one person to appear clearly on screen at a time.
Baird
1936 - 240
By the time the BBC decided to make TV an official offering in 1936 Baird had improved his mechanical system to encode images in 240 lines. The government forced this development because they defined “high-definition” as 'not having less than 240 lines per picture.’ But it proved not good enough in the end, with the last official Baird-style TV broadcast made in 1937.
4:3 became the standard for television because of the use of movie film in providing pre-made content. This was more true for Baird, when his company got owned by the Gaumont-British Firm Corporation in 1932.
Marconi
EMI 1936 - 377 x 503
Baird’s fully electronic rival was a co-development between Guglielmo Marconi and Electric and Musical Industries (EMI). Isaac Shoenberg decided on a risky gamble increasing the line count from an initial 243-line to 405. That number came about due to the work of Alan Dower Blumlein. Been better than Baird’s system, it became the UK’s standard until the adoption of PAL in 1964, leading to its final transmission in 1985.
Originally 5:4, the aspect ratio of the EMI system was later changed to the standard 4:3 in 1950.
Einheitsempfänger
1939 – 383
Germany had
been working on their own TV system since 1932. A 180-line system became
Germany’s first regular TV broadcast in 1935. In 1937 a 441-line system was
developed, leading to the Einheitsempfänger (or “Volksfernseher”) set of 1939.
Only 50 sets got made when war broke out and a transmitter in Berlin was
destroyed in 1943, but the system continued broadcasting by cable until France
was liberated in 1944.
Italy used it briefly from 1939 to 1940. It was used in France from 1941, until a fire destroyed the equipment in 1956. But by then, France had adopted an 819-line system since 1948.
The Einheits-Fernseh-Empfänger E1 was a one channel receiver with a 29cm 15:13 screen. It also functioned as a radio.
NTSC
1954 – 440 x 486
The first
successful colour TV system was based on the 525-line system used in the US
since 1941.To make it backward-compatible with black-and-white sets, colour and
brightness information are encoded separately. Georges Valesi came up with this
neat idea in 1938. But it had problems keeping the tint of colours consistent
in poor conditions, leading to some calling it “Never The Same Color.”
Westinghouse H840CK15 - the first NTSC TV ever sold.
It was this system that made the 4:3 aspect ratio the industry standard.
PAL/SECAM
1967 – 520 x 576
Colour TV
appeared in Europe in 1967 in two forms that solved NTSC’s tinting problems.
The Phase
Alternating Line system was developed by Telefunken of Germany and patented by
Walter Bruch in 1962. It was widely adopted across Western Europe.
SECAM (Séquentiel couleur à mémoire) was developed by Thomson of France and patented by Henri de France in 1956. Its adoption is questionable, but many say it’s due to politics and the charisma of Henri. Thomson later bought Telefunken in 1984.
SECAM was adopted by the Soviet Union because it allowed them to sell TVs that couldn’t detune Western broadcasts – unless they had an adaptor.
Telefunken PALcolor 708T – the first PAL TV 1967
The pixels on NTSC and PAL screens are not exactly square. In digital standards, pixels on NTSC are an aspect ratio of 11:10. PAL’s pixels are 11:12. This may explain why the NTSC image appears “fatter.”
Widescreen
One thing that came from HD was a wider screen. With HD coming, SD broadcasters needed a means to compete – and offering a wider screen was it. But widescreen TVs have been manufactured long before widescreen content aired. The first widescreen TV sold in the US was the Thomson (branded RCA) CinemaScreen of 1993. As the name suggests, it was made for movie buffs who owned a laserdisc player, which did offer widescreen content.
“16:9 is the geometric
mean of current television aspect ratio (4:3) and
the widest cinema
aspect ratio in wide use (2.35:1). It is also very very
close to the predominant cinema aspect ratio, 1.85:1.” – Charles Poynton, Usenet post (1994)
PALplus
1994 - 520 x 576
PAL+ was developed to make a widescreen format that was compatible with regular PAL TVs. Work on PAL+ began in 1989 with broadcasters adopting it in 1994. By 1998 nine European countries were broadcasting PAL+ regularly, making it the most used standard for widescreen TV in Europe at the time.
Nokia launched the first PALplus TV set in Germany in 1994.
Most sets receiving PALplus will show the image in the form of a 432-line “letterbox.” Information encoded in the vertical blanking interval tells the TV with PALplus that the signal is wide and adjusts the image to the intended full 576 lines.
Going HD
The term “High-Definition”
has changed over the years. Back in 1930, 100 lines was enough for a TV to
called High-Definition. Since the 1970s, it had meant 1000 lines. Just before
he died in 1946, John Logie Baird was working on a 1000-line system. France had
a black-and-white 819-line system broadcasting from 1948 to 1983. NHK of Japan
began working on 1000+ line HDTV in 1964, with working TVs demonstrated to the
public in 1969. In 1981 they began making content and demonstrated it in the
US. When president Ronald Reagan saw it, he was impressed and made HDTV "a
matter of national interest." Concerned by the idea of Japan leading the
field, the Americans began work on their own HDTV systems, leading to the
digital HDTV systems in use in the 21st century.
The analogue HDTV systems, however, were destined to fail. They required more bandwidth than SDTV, many needing satellites to work. There were attempts to make a global standard HDTV system, but the variety of pre-existing incompatible analogue systems worldwide made such a thing near impossible. It took until the advent of digital technology for HDTV to finally arrive.
MUSE
Hi-Vision 1991 – 1035 x 1920
This was the only analogue HDTV system to actually broadcast to the public. Regular broadcasting of Hi-Vision (using Multiple sub-Nyquist sampling encoding) was trailed in Japan in 1989, leading to official regular broadcasts in 1991. It went digital in 2000. The analogue system finally shut down in 2007.
Originally Hi-Vision was 5:3, but changed to 16:9
HD-MAC 1992 - 1040 x 1152
The Eureka Project in Europe began working on its own HD format - Multiplexed analogue components – in 1986 as a reaction against MUSE. By 1992 some sets were made and exhibited and demoed at the Olympics in Albertville and Barcelona. The plan was to have consumer TVs made from 1995 or later. But it was abandoned in 1993 when the European Commission decided not to subsidize broadcasters to convert to HD-MAC. This left Europe’s airwaves free for later digital systems. Europe’s first public digital HD broadcast was in Belgium in 2004.
ATSC HD
1998 – up to 1080 x 1920
In 1993 the MPEG-1 video compression format was standardized, beginning the true digitalization of TV. In that same year the FCC of America set up the Digital HDTV Grand Alliance to finally create a homebrewed HDTV system. The resulting Advanced Television Systems Committee HDTV system was tested transmitted in 1996, before officially launching in 1998.
4K 2012
- 3840 × 2160
IBM made the first screens able to display 4K in 2001. Consumer models first appeared in 2012, with content made a year later.
8K 2018 - 7680 × 4320
NHK had been developing “Super Hi-Vision” since 1995. Sharp and the NHK demonstrated the first prototype 8K display in 2011. The NHK launched the first channel to broadcast in 4K and 8K in 2018 - just as Sharp began shipping the first consumer model – the Aquos LV-70X500E.
Square Pixels
“In around
1988, 89, 90, I realized that HD was going to be used for applications well
outside just the distribution of entertainment programming. And so my goal was
to try to make equally-spaced pixels, because that’s how Landsat satellite
images worked. That’s how medical images worked. That’s basically how fax
machines worked. I saw that the long term was to make them equally-spaced.” –
Charles Poynton on why he wanted HD to use square pixels. It was to get rid of
image distortion when transferring images from one device to another.
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