The history of Character Generators A brief history of television graphics b y Ja m e s Gil bert, Pi x el Pow er T hirty years ago, television captions were routinely created by sticking white Letraset characters onto black card. Credit rolls were possible using special devices which used long strips of black material onto which the Letraset was stuck, and which were literally rolled, either by an electric motor but sometimes even by hand. There were, of course, a whole bunch of disadvantages in such a system, both obvious and perhaps less obvious. First, you needed people to do it: people you could trust to check the spelling and achieve a balanced layout, but who were stuck with a very boring and unfulfilling job. Second, you had to allocate one or more cameras to view them, and a precious effects bank in the switcher. These were the days when a studio would never have more than four cameras and a lot of programming was live, so this was a serious imposition. The caption cards were usually stacked on a music stand, and someone had to stand there and remove them when they had been used. You simply superimposed the output of the caption camera ­ white letters on a black background ­ on top of the picture (you still here some old school directors calling for "the super" ­ that is where the expression comes from). If you wanted multiple captions, you either used more than one camera or you had to keep switching the caption camera on and off. Those of you with very long memories may remember the original UK wobbly-set soap opera Crossroads. This made an effect of its end credits, having them flying in and out in turn from top, sides and bottom: done with two cameras panning and tilting. So there were real pressures on the industry to come up with an electronic replacement. While the first device in service was probably the Riley character generator, developed in association with the BBC, the real honour for pioneering commercial success must go to Aston in the UK and Chyron in the US. The honour takes the practical form of becoming generic trademarks. You still find people trying to hire an "Aston operator" (or, in America, a "Chyron operator"), even when they will actually be driving a Pixel Power Clarity (or one of the many other character generators now available). These early character generators were fairly simple devices, being effectively just a replacement for the Letraset and card by producing white letters on a black background to be superimposed onto the picture. Indeed, the quality of text was arguably worse, as at this time there was no anti-aliasing of the characters. In this case, aliasing is the jagged appearance of lines on a television screen which are not perfectly horizontal or vertical. What should look like a straight edge is rendered as a series of steps by the line structure of the television screen. Add in interlacing and it means that curves and angled lines will appear to crawl as well as look rough, particularly in relatively small fonts. Get the font size really wrong and you could end up with moiré patterns. Anti-aliasing minimises this effect by cheating the eye. It smudges the difference between the two fields of the interlaced frame. If you look closely it means that the edges of diagonal lines look soft, but from normal viewing distances it minimises the jagged steps and reduces other problems. Anti-aliasing was one of the developments that reached the character generator market by the late 1980s, at around the time that we founded Pixel Power to bring a new approach to the technology. We saw that the market was now beginning to demand more than just electronic Letraset, including a good approach to anti-aliasing and a much broader choice of fonts. There was also a requirement for more than just static captions: rolls and crawls were also added, by us and by our competition at the end of the 80s. This period also saw the first attempts at 3D character generators, bringing a greater range of animation to captions. Names like Floating Point, the Quantel Cipher and the Ampex Alex led the way in 3D. If these products do not sound familiar to you do not be surprised: they were all short-lived because practical, workable 3D graphics were beyond the technology of the day. Character generators were black boxes at this time, using bespoke hardware. Processing power was such that layouts had to be rendered before they could be used, and extended animated sequences were impossible because of memory limitations. The user interfaces also tended to be rather less intuitive than we would expect today, and operators needed an extended period of training. That was actually a major obstacle in the wider use of character generators: there was a shortage of welltrained operators, and once trained on the preferred machine, they tended to resist moving to another manufacturer and another user interface. Interestingly, although character generators are now much easier to use, the availability of operators can still be an issue, particularly in high pressure areas like live sports. And they are still often called "Aston operators", even though the chances are they are operating something else. If the 80s were characterised by the drive for good quality text, in the 90s the character generator started to become more than just a caption device. Pixel Power, and Dubner in the USA, led this movement, adding a stills store and paint >> Page 67 of 96