October 2009 Archives

ALT Tags Benefit Everyone

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I know I keep exclaiming that adding ALT tags to images benefit everyone, not just users on screen readers, but here is the perfect case of WHY it benefits users on visual browsers.

Here is a site in my bookmark archives which I apparently liked at one point. Today, though there were some problems with the images loading so this is what I saw:

White Screen with grid of rectangles with each with question mark

So what was this site about? If you said Underground Railroad, you should consider becoming a psychic.

Now let's show a good example from PBS where ALT Tags are implemented. Can you tell where the images used to be? I'll let you ponder that. You should however, be able to determine that you are on a site about fireworks...even without ESP. You can also see that there is a main menu to the main PBS sites including a program listing and the PBS store.

Click Image to open larger image

Below is the same site with images displayed. The main menu is now a set of images and the header includes a nifty image of a firework shell exploding with embedded links. Although there is some extra information with the images, in terms of navigation, I would say the site was very functional without them...because of the ALT tags.

Fireworks site with top menu changed and Fireworks header
Click Image to open larger image

Google Server Set Up and Neural Nets

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The keynote at the CIC Tech conference by Charles Severance was very informative if you are interested in Google. There were several factoids that I found interesting, but what I noticed the most is that the Google server architecture is sort of like a neural net.

When I was a grad student, I was introduced to the concept of a "neural network". The extremely simplstic idea is that individual neurons do one limited task and then send data to another neuron to do the next task.

I think the best example of a neural network I know is modeling color vision. For instance, you can begin with sensor neurons which detect different levels of light (e.g. detect level of red light vs detect level of green light). The sensor neurons can then send their input to another set of neurons which only have the job of this light level data into a simple calculation called "hue identification" (e.g. 100% red + 100& green = yellow), and then sends that data to another system (e.g. the general visual system then object recognition then word recognition etc).

Each neuron is fairly limited in function, but the architecture is set up to perform complicated tasks very quickly.

Getting back to Google, Severance showed a video about how a search query works. Between load balancers, data storage, querying and instant HTML publishing, a typical query can actually hit 1000 servers in less than 2 seconds. Holy You Know What!

More interestingly, Google apparently uses cheap servers. Apparently they use truck trailers worth (as in they plug in entire trucks of servers into a server farm). And apparently, they must have data centers all over the world. This apparently explains how Google mail can be efficient south of the equator when otherwise the Internet tends to slow down (at least between the hemispheres).

Severance called this "building a brain", and for once I don't think it's hype.

2 Accessibility Presentations CIC CIO Tech Presentation

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The first was given at the CIC Tech Forum conference on Oct 6 and discusses the challenges of implementing accessible content in an higher education environment, especially now that a "developer" may now be an instructor. A key factor is awareness, but ultimately the design of simpler tools is critical.


The second presentation will be given October 12 at the University Libraries as part of Accessibility Awareness Week. A few more concrete examples of accessibility accommodations are given.