Why can I tell when a higher res image is used in a web graphic?

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NleahciM

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Aug 2, 2002
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Hi - occasionally it seems people designing their websites will use a very large image in their HTML page and then resize it with the IMG tag as opposed to resizing the actual source file. I see this pretty regularly - especially in academic pages for whatever reason. The weird thing is I can often look at the image and just tell that it's being resized by my browser, as opposed to the actual source file being the same size as what is being displayed. I always verify this by dragging the image into the address bar of firefox and - sure enough - it is bigger than is being displayed.

My guess here is that the algorithm being used to resize the images on the fly in the web browser does it quicker but with lower quality than the algorithm a program like photoship would use?

Anybody know what I'm talking about?
 
NleahciM said:
My guess here is that the algorithm being used to resize the images on the fly in the web browser does it quicker but with lower quality than the algorithm a program like photoship would use?
Click to expand...

Exactly. Basically the web browser is not able to truly compress the image and show it at that size. Of course I'm sure theres a highly technical description someone might be able to give us, but you pretty much answered the question yourself ;)
 
Exactly. Basically the web browser is not able to truly compress the image and show it at that size. Of course I'm sure theres a highly technical description someone might be able to give us, but you pretty much answered the question yourself
Click to expand...

My guess is they're on insanely high connections and don't care about how fast the page loads on a slower connection.

Plus not every university department really knows about the real world but that's for another discussion :p
 
Valkhorn said:
My guess is they're on insanely high connections and don't care about how fast the page loads on a slower connection.
Click to expand...

In my experiences I've found that it's actually the opposite. They have pretty much no idea what they're doing, and their CMS doesn't handle image compression for them.
 
its called re-sampling (or lack there-of)

think about how when changing the resolution on a lcd, everything looks blurry wen it is not the native res. more or less the same effect

what makes it even worse is when they change the aspect ratio too.
 
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