Current Trends in IT Workshop 2: A) Creating Dynamic Web Pages B) Image and Multimedia Systems
PHL and JSH February 2006
A) Creating Dynamic Web Pages
In the first workshop you began to create web pages by writing html directly and also by using a web page editing package. The pages you created were essentially static documents which, once displayed, did not change unless a link was followed to another page. Frame sets allowed several pages to be displayed in frames on a single screen and the static information in frames could be changed but only by link following.
However, it is possible to make web pages more dynamic, for parts of the page to move or change and for there to be more interaction between the user and the web page. This can be achieved in a number of ways and these mainly involve writing (or using somebody else’s) scripts, which run either in the browser (client side scripting) or in the server (server side scripting). There are many scripting languages around but the main ones used on the web are javascript and vbscript.
In this part of the workshop you will modify some of your web pages or create new ones by adding client side scripts to make them more dynamic. There isn’t time in the course to learn a scripting language if you don’t happen to know one already, but as there are many collections of scripts to do all sorts of useful things freely available on the web, what you will be doing is to visit websites containing collections of javascripts, choose one that you would like to use, and copy and paste it into the html of your web page. Below (fig 1) is an example of the source code for a web page containing a very short script for changing the background colour of the web page by pressing a button. It uses the “forms” tag in html, which, among other things, allows you to create buttons. The calls to the function defined in the script, which changes the colours, are associated with the buttons via the “onclick” attribute. Don’t try typing this page in. If you want to play with it its available from the course web page or directly at http://www.ecs.soton.ac.uk/~phl/ctit/script2.html
Follow the link, try the buttons and look at the source. Try adding the script to your web page if you wish.
Now visit the website http://javascript.internet.com and choose a script that interests you, maybe one to provide a calculator, clock or calendar facility. The Background Color Changer is in the Image Effects section of the site. Some scripts are more difficult to install than others and involve separate files from the web pages. Go for scripts that look fairly easy to cut and paste in the first instance. There are other sites of javascript libraries, which you might discover with a search engine. See what you can find and try adding some appropriate scripts to some of your web pages.
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by The JavaScript Source
Figure 1 Web Page Source Containing Javascript
2 B) Image and Multimedia Systems
In the lecture, we have looked at some of the problems of information retrieval and multimedia information handling. In this part of the workshop you will visit some image and multimedia retrieval system demonstration sites and gain some practical experience of developments in image and multimedia systems. . Remember that compared with text, image and multimedia retrieval using content is in its infancy.
First use Google to retrieve images using some keywords. (select the images button above the Google search box and enter a keyword).
Try, for example, the keyword tree to get tree images. You will see that you get a variety of views of trees, long shots, close ups etc and if you look on later pages you will see images of tree like networks and other non green tree like images. You may want to say “give me more examples that look like this or that particular image”. That is, you want images with similar content.
Google indexes images using words associated with the images.
Now visit http://wang14.ist.psu.edu/cgi-bin/zwang/regionsearch_show.cgi This is a site that allows you to search using image content. For example, you can say find me more images that look like this one. Some research groups have demonstrations of their content based retrieval systems e.g. there is another at http://www.cs.washington.edu/research/imagedatabase/demo/ch/
Explore these sites and learn a little more about the research they are doing.
People are also beginning to store 3-D representations of objects in their information systems not just 2-D images. Retrieving 3-D objects by content matching is a growing research area.
An example of a system for 3-D matching can be found at: http://shape.cs.princeton.edu/search.html
Visit the site and experiment with the retrieval system
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