alt Tags and Photo Galleries
The HTML <image> tag has a number of attributes which are important both for appearance and for search engines.
Search engines are generally not intelligent enough to figure out what an image contains by themselves. So they use the "alt" attribute which is intended to describe an image when a web page is viewed in a non-graphical web browser.
Google does attempt to figure out what an image contains in the absence of an "alt" attribute by having two users simultaneously view and name keywords associated with an image. Keywords in common named by both users are then assigned to an image. This is a novel approach but only a very small portion of potentially indexable images can be assessed in this manner so you should include "alt" attributes even if Google is the only search engine of interest.
Two other attributes are advertised as being available to resize an image but they actually should be included even if you wish the image to display at it's native size. These are the "height" and "width" attributes.
The reason the "height" and "width" attributes are important even when an image is to be displayed at it's native resolution is because, if a web browser can get this information, it can layout and display the text of the web page with the correct formatting even before the images are downloaded and then fill in the images as they are downloaded.
This is particularly helpful to people using a dial internet connection or using a slower computer or an operating system such as Windows XP that limits the number of simultaneous half-open connections and thus slows the downloading of images if there are many images on a page.
Here is an example of an image tag nested in center tags to center the image:
Search engines will index the keywords "Alien" and "Sunset" as well as the phrase "Alien Sunset". Without the "alt" attribute these keywords will not be indexed.
Photo gallery software presents a problem in that you may not have control over these keywords. Coppermine Photo Gallery usually places the filename in the "alt" attribute. This is not very useful unless you name your files very descriptively. Sometimes it is even worse and places phrases like, "Click to Enlarge" in the "alt" attribute. This is particularly useless since someone using a non-graphical viewer won't be able to view the enlarged image any better than they can view the normal or thumbnail images.
The easiest thing to do if you want photographs in Coppermine to be indexed is to name your files descriptively. Alternatively, you can hack Coppermine to use the file description information in the "alt" attribute. The latter is not a simple task because it can't be done without actually hacking the core code because some of the underlying functions do not retrieve all of the necessary information from the database without modification, thus a complete modification is not possible through themes alone.
Search engines are generally not intelligent enough to figure out what an image contains by themselves. So they use the "alt" attribute which is intended to describe an image when a web page is viewed in a non-graphical web browser.
Google does attempt to figure out what an image contains in the absence of an "alt" attribute by having two users simultaneously view and name keywords associated with an image. Keywords in common named by both users are then assigned to an image. This is a novel approach but only a very small portion of potentially indexable images can be assessed in this manner so you should include "alt" attributes even if Google is the only search engine of interest.
Two other attributes are advertised as being available to resize an image but they actually should be included even if you wish the image to display at it's native size. These are the "height" and "width" attributes.
The reason the "height" and "width" attributes are important even when an image is to be displayed at it's native resolution is because, if a web browser can get this information, it can layout and display the text of the web page with the correct formatting even before the images are downloaded and then fill in the images as they are downloaded.
This is particularly helpful to people using a dial internet connection or using a slower computer or an operating system such as Windows XP that limits the number of simultaneous half-open connections and thus slows the downloading of images if there are many images on a page.
Here is an example of an image tag nested in center tags to center the image:
<center>This will display like this:
<image src="http://www.eskimo.com/~nanook/gallery/albums/userpics/10001/normal_ALIEN_SUNSET.JPG" width="640" height="480" alt="Alien Sunset">
</center>
Search engines will index the keywords "Alien" and "Sunset" as well as the phrase "Alien Sunset". Without the "alt" attribute these keywords will not be indexed.
Photo gallery software presents a problem in that you may not have control over these keywords. Coppermine Photo Gallery usually places the filename in the "alt" attribute. This is not very useful unless you name your files very descriptively. Sometimes it is even worse and places phrases like, "Click to Enlarge" in the "alt" attribute. This is particularly useless since someone using a non-graphical viewer won't be able to view the enlarged image any better than they can view the normal or thumbnail images.
The easiest thing to do if you want photographs in Coppermine to be indexed is to name your files descriptively. Alternatively, you can hack Coppermine to use the file description information in the "alt" attribute. The latter is not a simple task because it can't be done without actually hacking the core code because some of the underlying functions do not retrieve all of the necessary information from the database without modification, thus a complete modification is not possible through themes alone.
posted by Nanook at 4:39 PM
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