ayg wrote:

This is only potentially possible when browsers consistently implement reasonable client-side scaling. Since scaling is presently server-side so thumbs don't look like garbage, we can't know what resolution the user is using. And then there's the issue of caching.

nichalp.wiki wrote:

Forgive me for asking what may be a stupid question: But when a user logs into the site won't the header information grab the user's browser resolution and mediawiki automatically serve up the appropriate image resolution if not already specified?

(In reply to comment #1)

This is only potentially possible when browsers consistently implement
reasonable client-side scaling. Since scaling is presently server-side so
thumbs don't look like garbage, we can't know what resolution the user is
using. And then there's the issue of caching.

• This bug has been marked as a duplicate of bug 495 ***

ayg wrote:

(In reply to comment #2)

Forgive me for asking what may be a stupid question: But when a user logs into
the site won't the header information grab the user's browser resolution and
mediawiki automatically serve up the appropriate image resolution if not
already specified?

I'm not clear on what you're asking, but any attempt to serve different images to different anons based on screen resolution will lead to large-scale cache fragmentation, which is not acceptable for performance reasons. Perhaps that answers your question.

HTTP header information does not include screen size.

It's possible for *client-side* JavaScript to request screen size from the browser, but:
a) that runs on the client, hence after you have sent content
b) that only runs if JavaScript is enabled
c) the browser may or may not return a value
d) screen size, geometry, and resolution can vary quite a bit
e) users' preferences can vary even more

While it would be possible to rig up something that made images bigger for people with big screens, it would likely be more effort than it's worth and make more people annoyed than it would make happy.