The Font Magicians - Computerphile

bell labs got its first actual laser printer in 1982 which i think was from a company called imogen now in those days yeah you could get them but the big problem the big big problem was fonts it wasn't by any means impossible to get laser printer technology at lower resolution than the omnitech was doing more reliable in nottingham we asked for a price i think for an imogen uh early laser printer and we were told it will be eighteen thousand dollars in the uk which would have translated to about fifteen thousand pounds it's ridiculously expensive if you're getting to lower resolutions like three hundred dots per inch what then happens is that your eyes are sensitive enough to notice roughnesses on the edge of the character in other words the pixel density at 300 dpi is such that if something goes wrong in terms of the pattern of pixels and you get a fault at the edge of the character your eyes notice it at 972 dpr they probably wouldn't notice at all so the burning question was how can we do this rounding problem if you like we've got these beautiful outlines we need to translate them into dot patterns how do you work out which pixels to turn on which to turn off and if you've got half a pixel by the time you've done your calculations do you turn it on and you turn it off and of course you can imagine what happens it looks bad if you didn't turn that pixel on it looks even worse if you did turn it on you just couldn't win it was a huge problem and within the industry there was the most ferocious debate with within xerox canon wherever and even many of you know the computer scientist who got involved around about this time with typesetting don knuth and the consensus was that down at low resolution you just had to have hand-tuned bitmap fonts with all the pixels put in place correctly there was no shortcut there was no way that you could if you like on the fly scale down from outlines to dots on a drum and get it right automatically hand tuning was the way forward well if that was the case it was a real mess because it meant that your laser printer had to be backed up with an expensive hard disk or cartridge system and some commenters already on the jailbreak system have used these have said what a nightmare it was you had a very restricted range of fonts they never seemed to work correctly and that whole disc instead of holding 50 or 60 different typefaces it was devoted to holding times roman hand tuned in about 40 usable point sizes stuff like that the thing that kept us going though the rumors on the horizon if you like were that two people working for xerox park called warnock and geshke were about to leave xerox park and form a new company called adobe now the moment you say xerox park you start thinking we need a complete new video just on that alone park parc palo alto research center if bell labs was the one place that everybody wanted to work at in the 1970s then xerox park was certainly the other and there was a similar background in some ways um bell labs had lots and lots of money um because of a tnt but of course they were under consistent scrutiny for for monopolistic practices and don't you ever dare turn yourselves into a computer company it wouldn't be allowed xerox probably didn't have quite as much money as bell labs but nevertheless even today xerox i think turns over about 20 billion dollars a year so they could afford a vanity project and they did the xerox palo alto research center was run off the xerox publicity budget that's how much money xerox were making i probably still do make out of just being a photocopier company but at xerox park they invented either invented or had a very strong development role in all sorts of things that are now commonplace the computer mouse the laser printer bit mapped terminals which we take for granted nowadays but if you skip back to my earlier video on from mainframes to unix just take a look at what the old character terminals used to be like sort of cells of dots about nine by nine with your characters you certainly couldn't get down to the bit level on your screen but with bitmap terminals you could they had under development at xerox part things with names like alto and dorado bitmap terminals wonderful and they had bob metcalf there they were crucially involved in the development of ethernet they had it all they had all the necessary components to pioneer the next stage of computing if you like the workstation revolution but in a book i think called fumbling the future the author of that book makes the case that they fumble it they let it all fall they didn't market it and they could have done well to be fair to xerox at the time you could argue they made the right decision turning yourself into a computer company is hard to do if you're not a computer company already and wonderful though their technology was it was reckoned at the time that the cost of the components alone in mid 1970s money to make an alto terminal the components alone would have cost ten thousand dollars if they were mad enough to go into marketing the thing they would have had to charge at least 25 000 in 1975 money probably about 250 000 in today's money so you could say in a sense they had to wait for the cost of the technology to come down and they had to accept that all these toys were very very expensive indeed now the only problem was with sitting on and developing all this wonderful technology was that the hot shot computer scientists you'd got working for you got very frustrated that their wonderful inventions and developments were not being marketed and so gradually as the 70s wore on into the 80s people began to leave and form their own startups chugeshke john warnock both considerable computer scientists in their own right were working on xerox's interpress language and just got so frustrated with xerox's inability a lack of will to market this properly that they up sticks left and formed adobe which you've all heard of in late 1982 i think they initially decided that they were going to go for the high-end typesetting market soon after they left and founded adobe john warnock got to work on a language that's achieved great fame ever since called postscript i think it very carefully avoided the precise way that interpress had done things and it reverted back to lots of john's earlier work because he was a computer graphics specialist who came out of the university of utah and also worked for the graphics company called evans and sutherland and in his phd had solved the infamous hidden surface problem which had defied efficient solution for quite some time i think i've already told you in the video i did about david huffman at huffman trees his phd thesis was 12 pages i think john told me that his uh phd thesis about solving the hidden service problem was a little bit bigger all of 32 pages so here was this computer scientist a computer graphics expert joined up with another considerable computer scientist chuck geshke it was the ideal combination to found this new company john came up with this language called postscript which was going to be a tour de force of two-dimensional graphics and it was and more to the point he was going to get to grips with solving this problem of how to make fonts look good at low resolutions you want to hold the outline of the font as arcs splines lines whatever for as long as possible but in the end it has got to get down to being pixels it's got to be dots on a laser printed realm and in fact there's some other stuff of course john chapman's uh videos on computer file so relevant to this you really ought to watch them so here's some more detail which relates to that oh by the way thanks to photographer those of you want to know how i did the uh so-called print out font in the jailbreak video i think the papers that we web linked to make this clear but anyway i use photographer and within the photographer manual there is a very useful pair of pages which makes very clear this difficulty with getting characters to look good on a course resolution consider a letter h here's the outline superimposed on top of a grid of pixels now how do you decide which pixels of these vertical stems to be colored in if you follow the argument that a pixel should be made black only if it's totally within the outline then if your outline isn't quite as helpfully aligned with the pixels as it might be this is what you end up with on the left hand side the only ones that are totally within the outline is a single column whereas on this side there's two columns if you back off take away the grid of pixels at the back and look at what the character looks like it's awful you know you've got uneven stem widths and do notice in these of course the crossbar is gone on the h isn't that wonderful of course it would go it's so thin in that desire in that design it's been rounded down and it's vanished completely here's another thing even if you could solve that these flicky bits as we know are the tops and bottoms of characters i think probably everybody knows they're called serifs well you need your series to look good as well and if you're not careful you can end up with the stems getting better and more equal but the serifs having no symmetry whatsoever even though they're supposed to be the same shape the precise way they align with the grid underneath is such that they don't look symmetrical anymore whereas they were in the first instance and then you can say oh could we solve all of this by saying well tell you what we'll turn the pixel on if any part of it touches the outline however glancing if you like the impact is between the pixels and the outline if it's at all remotely touching turn it on and that's the kind of mess you end up with if you do that so what you needed was a system of what came to be known as hints on the diagram is here for the letter m hints show all the places in which the adobe type one font system actually said mattered hints about the serifs these are important take care hints about horizontal lines like on the h don't round it down and don't have it disappear altogether within the font mechanism it was basically when you are scaling down the outline and as john chapman's videos will also show you in the end although you can delay doing a straight line approximation to curves in the end that's what you do you end up with triangles and polygons okay and then those triangles and polygons you work out where they intersect with the underlying pixels and so on so later on in the process and this is the advantage of this more modern approach compared to the 202 rather faster processors you can leave the as it were translation into straight line approximations and pixels until the latest possible moment thereby giving yourself flexibility now this shows you this is line of type 202 resolution up at the top that is the base i think of a stem of a letter h or i or something like that it something more like 970 dots and you will see there's no problem if you back off from that your eyes are probably not sensitive enough to notice the odd pixel that's gone astray but down at 300 dpi they certainly will and of course the problem manifests itself hugely at 300 dpi if you have small point sizes like six point or eight point you end up if you're not careful with everything looking just like a full stop because there's been so many errors so this is why you need these hints you need stem hints you need serif hints you need hints to stop horizontal things vanishing altogether due to rounding down john warnock was the recipient of a very prestigious medal called the loveless medal and my friend conrad taylor has done a report on that talk which um he's happy for us to use and in conor report you will see that john warnock actually admitted 20 years after the event that there was another dirty trick that they did as well as if you like as part of the hints that they didn't let on about if you look back at this diagram here and how it translates to turned on pixels here although we will enrage the type designers there is a way that you can help yourself here type designers like calling the gap to the left of a character the left side bearing and the gap at the right of the character the right side bearing now if you look carefully the left side bearing here is ever so slightly wider than the right side bearing this is part of the design you position your character within the cell so it looks right in all combinations with all other characters and even in a fixed width font like print out of the previous video you found the left and right side bearings are still not equal yeah but what john and his merry men did their type 1 renderer was to say actually although the designer will kill us they probably won't notice if at the very last minute we just shove the letter h ever so slightly further left okay so this instead of ending up with a one pixel line and a two pixel line you might end up with both of them being one and a half because you've made the alignment of the character against the background grid be just much more sympathetic and if it's one and a half it doesn't matter whether you round both sides to one or round them up to two they are at least going to be equal okay that's going to help a lot so he actually admitted in 2004 that it was not beyond them to ever subtly shift the character within its unit cell to get a better alignment and a better result so that is then pretty well a summary of what had to be done what had to be got right with hinting before if you like quality font stood any hope of working properly with laser printers john warnock put the postscript language effectively into the public domain and said go on implement it i want it to be a standard you know implementation is the sincerest form of flattery as one of the first implementers said but the story was this you can use all the graphics operators in postscript you could do a pretty acceptable font that way but it was what adobe called at the time a type 3 font it did not have these hints to enable you to survive and make it look good down at very small point sizes on low resolution devices if you wanted that then back in 1918 from about 1985 to 1989 you had to sign a contract with adobe to license their hinting technology and this was secret this was one of the ways that adobe as a young company wanted to make money they were selling implementations of course to other printer manufacturers but there's a nice font revenue stream from licensing people to put type 1 hints onto adobe type 1 fonts so there we are then there's another story to come here but we'll get on to that later about how adobe survived with that model for about four or five years but eventually gates and jobs were not gonna pay endless royalties for type 1 to john warnock dearly though they loved him and we could do a talk at some stage about the emergence of true type out of that but for the moment here's the story then you needed a laser printer equipped with postscript but with postscript plus the ability to cope with type 1 fonts and do be clear this hinting information things like these stems should be of the same width that crossbar on the h don't round it down and don't lose it this is used at the very last moment when you're converting things into pixels on the imaging drum and it's ultra ultra important that you get it right but effectively john and his merry men with postscript had and the hinting had solved a problem which many people in the industry said was insoluble you know there isn't a way to take outlines and round them down to all point sizes and make it look good well you might say that some of the tricks that john did were compromises and were a little bit short of perfection but frankly even to type professionals i don't know if you did an a and b you know hand tuned bitmap h versus what the adobe type 1 mechanism did with that h okay with a good microscope you'd notice the difference but for everyday use no problem at all the problem was solved essentially i've got hold of here a reproduction of our party piece that we used to do for people on the 202 can you imagine that in beautiful fresh gleaming bromide the next thing you do this is great fun is to decorate the tree i now want to from this work out what the correct code the minimal code should be for a given state

Channel: Computerphile

Views: 358,834

Keywords: computers, computerphile, computer science, adobe, fonts, post script, Professor David Brailsford, xerox parc, PARC, Palo Alto Research Centre, Bell Labs, University of Nottingham, John Warnock, Charles Geschke, Chuck Geschke

Id: jAdspOtgciQ

Length: 19min 31sec (1171 seconds)

Published: Fri Jan 31 2014

Reddit Comments

[u/311TruthMovement]

What's incredible is that we still haven't solved the hinting problem. All high-quality typefaces include hinting, which is an incredibly laborious and time-intensive process. TrueType hinting is the hardest.

[u/junk_fungle]

rather verbose