Status-Q

One of the challenges, when storing or transmitting the image of a scanned multi-page document, is that it takes an awful lot of space. Unless, of course, you compress the data. But how should you do this?

The kind of lossy compression used by the JPEG and MPEG standards is great for photos and movie frames, but not much good for text – it makes the edges blurry. And the hard-edged, often lossless, compression used by things like PNG and GIF is great for text but will do nasty things to any embedded photos or background textures. So how do you handle, say, a typical magazine page, with crisp text, embedded photos, graduated background colours?

In the late 90s, my friend Yann LeCun and others created the DjVu format, which cunningly works out how to split a document up and compress each bit using the most appropriate system, then reassemble them for viewing later. It was particularly good for things like digitising historical manuscripts – it would separate the script from the parchment, deal with them separately and still produce a realistic-looking copy afterwards, but take a fraction of the amount of data that most other schemes would have used; especially important in those pre-broadband days. The same concepts are now in the JBIG2 standard, which is included in PDF and embedded in many devices, including Xerox copiers.

Another way to save space and time is that, once you’ve separated the text and other symbols from the background, it’s fairly easy to see if any symbols are re-used. So you don’t have to store the image of every ‘e’ in the document – you can store a representative sample of each size, font etc and simply insert an appropriate one wherever it is used in the original. All very cunning.

Assuming you get it right.

But this story on the BBC describes how some Xerox photocopiers may not have been getting it right, occasionally substituting incorrect digits in their copies. This can be something of a problem if you are, say, an accountant, or an architect. It’s not clear from this article whether this has ever caused anybody serious problems yet, or just been noticed in the lab, but you can imagine the potential lawsuits…

It’s a potential danger of any technology that reassembles a perfect-looking output, when in fact some data may have been lost since the input. You could save a lot of mobile-phone bandwidth if you noticed that someone had just used the same word that they used a few minutes ago, for example…

Xerox fought hard to preserve their trademark by not allowing it to become a generic verb meaning ‘to photocopy’. But I guess they’d like it less if it came to mean something else.

“Ah, hello, is that my tax accountant? I was wondering if you could…. ahem… Xerox this year’s figures for me?…”

Thanks to Mike Flynn for the link.

This is pretty cool. Some German physicists have done some awfully clever quantum stuff and frozen light for a whole minute within a crystal. What makes this even more impressive is that they used it to store and successfully retrieve information – a simple image of three light-coloured stripes.

I think this may prove to be an iconic image in the history of IT, because this technique may enable storage in optical computers in the same way that mercury delay lines did in the early days of electronic computing, before we had RAM.

And wouldn’t it make a great plot device for a Star Trek episode?

More information here – thanks to Anthony Albertyn for the link…

My Photoshop skills are a bit rusty, but I revived them over the weekend for a quick job on behalf of Rose’s college. They have been contemplating the possible hanging of a large painting in a couple of new locations, and wanted to get a feel for how it might appear.

The painting, however, is over 2m square and currently in storage, so just holding it up for a moment while someone else gives their opinion would have been a little impractical. So I offered to do a quick non-artist’s impression.

Isn’t technology wonderful?

I’ve spent the last couple of days in Winchester, helping my brother & his family move house. All went well in the end, but we really need to fix the archaic English system of money transfers that happen on the day.

For those unfamiliar with the process, it usually involves the first solicitor in the chain pressing a button on some system which transfers the purchaser’s money to the vendor’s account, and unless there are cash buyers in the chain of purchases, this proceeds from solicitor to solicitor during the course of the day. When confirmation of each transfer is received, the estate agent hands over the keys.

In our case, five family members plus two removal men and a very large truck were waiting outside the house for a couple of hours until one solicitor came back from lunch, only then to discover that another solicitor had pressed the wrong button at 8.45 that morning so nothing had transferred. But nobody had informed anyone…

A similar confusion then happened later in the day to our vendors when they arrived at their new house… they had the keys, their belongings were being unloaded onto the front lawn, and the estate agent then screeched up in the car and tried to take the keys back because someone had misread the confirmation about their transfer and it hadn’t actually gone through.

I suspect other countries have this sorted out in a much better way which takes the unreliable lawyers out of the loop. Not least Scotland. They’re canny that way…

Recently, I’ve adopted the somewhat complicated habit of having several jobs at once. It’s not always the most productive way to work, but it keeps me on my toes, and life is never dull! And so, today, I started a new job, as a Research Associate in the Cambridge University’s Computer Lab.

Now, this is only one day a week, and it’s a fairly junior post, but it has significance for me, for several reasons. One is that it’s with an old friend, Frank Stajano, helping on what should be an interesting project. A second is that it’s nice to have at least a modest foothold back in academia, doing stuff that isn’t primarily profit-motivated. But thirdly, I’m enjoying a bit of nostalgia.

You see, I’ve been here before.

Just before I started my PhD, I also had an R.A. post in the Computer Lab. And many great people from that time are still around. So in some senses it feels familiar.

I have a shiny new Linux machine on my desk. Well, I had a Linux machine back then, too, but it was rather different. I had commandeered a spare PC and installed this newfangled operating system on its hard disk. I’d experimented before with booting Linux up from floppies, but to have a machine which I could, at least temporarily, dedicate to this skunkworks experiment was wonderful, and it had a decent CPU with enough RAM and disk space that I could run a graphical interface on it! I think I’m probably the first person in the lab to have used Linux with X Windows, which seems remarkable now, when it’s on the majority of desks in the department.

Other things have also changed, not least the building in which the lab is located. The phones on the desks are connected by ethernet cables, not by phone wiring, but of course, I’ll scarcely use it because I now have a phone in my pocket as well. Wow.

But the other thing that really makes me feel old is that the last time I started a similar job to the one I started today, in the same organisation, not one of us had ever heard of the World Wide Web, for the simple reason that it didn’t yet exist.

Gosh, I’m ancient…!

Economically, there are two kinds of people/households in this world:

• Those who pay more taxes than they consume.
• Those who consume more taxes than they pay.

It’s a fairly arbitrary line to draw, and I wouldn’t want to make any value judgments based on it. It’s tempting to call them ‘wealth-generators’ and ‘wealth-consumers’, for example, but that’s too simple. Most teachers fall into the second group, but without them, we’d have fewer people able to be in the first group.

Those in the first group are typically creating value by selling products or services that people want directly. Many of those in the second are doing the same thing, but we buy their products and services via a distributor known as ‘government’. That, to a large extent, is what taxes are.

But I just thought it was an interesting thought experiment, if nothing more. What’s your family budget deficit? How much are you dependent on government subsidy?

And if you don’t like the answer, comfort yourself with the thought that, thankfully, not everything revolves around taxation! How does your balance sheet look in other areas?

• Those who generate more happiness than they consume.
• Those who consume more happiness than they generate.

That’s much more important.