Screenfont.ca

Interview with John Gill

On 2001.11.19, we conducted a phone interview with John Gill, chief scientist of the Royal National Institute for the Blind, on the topic of the development of Tiresias Screenfont. (The interview was later used in a relevant article and sequel, both of which we hope you have read.)

We re-checked our notes and can now publish nearly all of Gill’s remarks from that interview.

Why doesn’t Tiresias Screenfont have an italic?

“In some versions the fonts are italic” – PCfont, Infofont, and Signfont. European version of Screenfont does not have an italic; the American-market version will, but it isn’t made yet [and still doesn’t exist in mid-2005]

“USA subtitling requires italics and bold which are not used in European subtitling.” [Bold is not used in Line 21 or DVD captioning.]

The old teletext Mosaic font didn’t have an italic. “The problem on a television screen at the size is to create an italic that actually looks like an italic.... And you can [typeset] it over patterned backgrounds and do 1,001 things wrong with it.”

Why was Tiresias necessary?

It was “one of these things that happen for all the wrong resaons.” He switched on subtitles one day in 1998 while his wife was on the phone. “I decided they weren’t that easy to read.” He asked a friend in digital TV, who told him that, in two weeks’ time, as it turned out, the digital-TV infrastructure would ratify the use of Mosaic for the next 50 years.

Gill had to find something “free of copyright” and better than Mosaic. Looked at 4,000 fonts and “liked none of them. They did not meet our criterion for legibility. That is our criterion – legibility, not beauty.”

The old Mosaic font had four lines of 36 characters, with 4:3 and 16:9 aspect ratios. “What can we make clearest in that space provided?”

BBC and ITN “made up a lot of videos for us with a whole lot of different variants for us to do testing” and “helped us with facilities.”

“We did not know enough about the finer points of typography, to say the least, and we knew very little about hinting.”

The ultimate team had “15 people in it, all of them unpaid.” “We had a variety of expertise.”

BBC and ITN also wanted to use it for teletext, but it needed modifications because its numbers and math characters were proportionally-spaced.

“It took more than two weeks. The first version took a year and a bit, and a lot of work was done in the first six, seven months, and there’s always a polishing, etc., that has to go on, and checking for kerning pairs, this sort of thing.”

They created derivative typefaces – PCfont, Infofont, and Signfont.

What did you fix?

“We started in this mad way of working from the opposite end from most people, and most of us work in the area of people with low vision, and we had a lot of sensitivity to that end of the business, and looking at how you differentiate one character from the next. What we’re finding [of interest] in the PCfont is you’ve got E-mail addresess, passwords, etc., where you mix letters and numbers together.” The difference between l and 1, for example, is “suddenly important.” Even RNIB flubbed that on his own business cards.

“We basically had to allow for the poor resolution of the television screen.”

What about hard-of-hearing people?

“It hadn’t occurred to them to ask ‘Could it be easier to read?’ ”

“On the television system, on the subtitling, it comes out in one size, and we specificed the size to make optimum use” of the available space.

Teletext users wanted four sizes. “If you want this free of charge, you’re going to have to agree with us on what sizes to use,” most importantly the minimum size.

How do Screenfont and the other variants differ?

“Because the hinting and the sorts of presentation we have to do.” The typeface “doesn’t vary that much between Screenfont and PCfont. They’re remarkably similar. But the technology that had to be used for delta hinting and that sort of thing was very different from that which you use for rendering.”

Infofont is bolder than PCfont, but the letter e had to be tweaked. Signfont is bolder still.

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