Joe Clark: Accessibility | Design | Writing

Don’t show printouts to grannies and call that a test

Speaking notes from a presentation give 2007.09.12 at TypeTech, ATypI Brighton 2007.

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Why is the function of caption and subtitle fonts important?

Today we’re going to look at just how pathetic the research into screenfonts for captioning and subtitling is, and come up with some principles for new research into those fonts.

Now we have to talk about the distinction between captioning and subtitling

First, let’s define our terms.

(Further comparison.)

We all speak English here, and many of us grew up speaking it, but that doesn’t mean we all speak the same dialect. The same word doesn’t always mean the same thing to different people.

Sometimes we have more than one word for the same concept, like lift and elevator, or trunk of a car and boot of a car. That’s one case: Two different words for the same meaning.

Or we might use one word with two meanings. A good example is pants: Does it mean trousers or underwear? You can explain which meaning you intend by using a different word. Say the word pants, explain with the word trousers. Or explain with the word underwear.

But that is not what’s going on with the words captioning and subtitling. In U.K. and Irish English, subtitling simultaneously means captioning and subtitling. It isn’t like pants meaning trousers and underwear; that’s three words for two concepts. It’s subtitling meaning subtitling or captioning, one word for two concepts.

This is really important. Subtitling and captioning are two different things, and you can have both at once.

Caption at top, subtitle at bottom
Subtitle at bottom, caption at top right

But in Irish and British English, you cannot differentiate the two things. This, my friends, is not a dialect difference but simply a mistake.

Captioning is captioning and subtitling is subtitling.

Reading off a screen

If you watch TV two hours a night five nights a week for a year, you’ll probably read 4.4 million words just off a screen in that year.

Jensema (1996) surveyed reading speeds of many television genres and display forms (scrollup vs. pop-on). Working solely from his reported averages, in words per minute (wpm) and per hour (wph):

Assume 25% of your viewing is scrollup, 75% pop-on. Two hours a night, then, equals:

0.25 × 2 × 9,060 + 0.75 × 2 × 8,280 = 16,950 words/night

Over 5 nights a week for 52 weeks, you’re reading 4,407,000 words a year.

If we assumed all scrollup captioning, the figure is 4,711,200. With all pop-on captioning, it’s 4,305,600. So the order of magnitude is the same.

Even if you do the same calculation with the very slowest captioning reported by Jensema (74 wpm), simply an impossible scenario even for young children abandoned in front of the TV by their moms, the order of magnitude is still comparable – 2.3 million. (With the maximum, 231 wpm, it’s 7.2 million.)

But you’re doing all that reading for pleasure, so reading all those words has to not hurt.

Let’s walk through some of the technologies that are used to display captions and subtitles

(See my hundreds of caption and subtitle photos up on Flickr.)

Line 21

Here are three of my old external Line 21 decoders. (They’ve all been superseded by decoder chips built into TV sets.)

Three machines in a stack: Small chrome, large chrome with red LED display, very large half-chrome/half-woodgrain with rotary dials

I was planning on taking some custom photos for this presentation, and I thought: What would be the most ridiculous possible thing to photograph?

Me holding ‘Sailor Moon’ videotapes

Well, Sailor Moon, of course. But I ended up with some unusable photographs.

Then, to show you how things were like with the original decoder, after a lot of cursing and frustration I managed to get it hooked up and I got it decoding actual 21st-century TV programs.

Screenshot shows italic mixed-case text with no descenders and a coarse dot matrix (hard-to-read a and y)





DVB is a digital television standard in the U.K. It uses bitmaps for captioning. We’ll be talking all about those in a while.

Online captions

Online captions can be closed captions. This is pretty stupid, because it replicates the broadcasting model. You don’t have only one channel online that has to serve everybody, deaf and hearing; you can upload as many video files as you want. Still, you can produce closed captions for all the main video formats, including Flash. They use the fonts on your computer.

Jeffrey Zeldman in a video image with caption below


So those are the technologies we’re dealing with. And, typographically, they’re all crap!

Some general typography features:

The state of the art is a disaster

Let’s come back to the U.K. and talk about DVB, the standard for digital broadcasting.

But it gets worse!

How is research going to fix this problem?

Well, it can, but first we’ll have to flip around the way screenfonts for captioning are developed.

These projects are not driven by type designers, and type designers aren’t picking the existing fonts to compare against. Researchers are running the show, and they can barely distinguish between Courier (“New”) and Times (“New Roman”).

Researchers always end up picking ridiculous candidate fonts that nobody with any type knowledge would ever use.

There’s already a model we can emulate. Let’s look at a book you should all buy: Vision and Art: The Biology of Seeing by Margaret Livingstone. She explains how the eye and the brain interpret visual images, and offers some ideas about how artists might have been subconsciously using those physiological phenomena in the creation of their art.

So yes, when you’re developing screenfonts you always look at the physiology and data from subjects, but you start with the actual knowledge of the artistic field, in this case type design. You start with that even if that knowledge isn’t written down or everybody you’re working with cannot see the differences that are as plain as day to you and me.

To develop screenfonts for captioning and subtitling, you start with the knowledge and intuitions of type designers and then you test. You don’t let a blindness researcher tell you how to design your font, then gin up some experiments that half-assedly “confirm” how good your font is. You never let a researcher tell you they want function and only function, not “beauty” or “æsthetics.” Because what they call beauty or æsthetics are the features that you know will influence function.

In other words, whatever they did with Tiresias you do the exact opposite.

Principles for designing and testing screenfonts for captions and subtitles

  1. Use actual video. Genre is important. No sex or violence; it’s too distracting.
  2. Choose viable candidate fonts. No Helvetica, Times, Courier, or Arial. Use your own expertise to pick them.
  3. Test real caption features. Use real positioning, colour, italics.
  4. Don’t fake a background mask. Get it exactly right.
  5. Don’t test only signing deaf people. They aren’t the only audience. You have to test hard-of-hearing and hearing people, and in fact two groups of hearing people – native speakers of English, or whatever language, and ESL speakers too. In the U.S. and Canada, hearing people are the majority audience of captioning.
  6. Test performance, not opinions. Test accuracy or retention of facts or eye motions. Do not ask what people think of the font, or, if you really have to, ask at the very end.
  7. Test in all upper case and in mixed case. Captions that scream at you in capital letters are still common and will be for decades.
  8. Test in all presentation modes. Line 21 has three presentation modes, but only two are widely used (pop-on and scrollup). Teletext has two.
  9. Test in all pixel aspect ratios.
  10. If you’re testing existing fonts, test default and wider tracking. Existing fonts are usually too tightly spaced.
  11. Test the extreme cases, too, like cursive and casual fonts in HDTV, because if they’re available then people will use them.

There are some unresolved issues

Posted: 2007.09.18

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