finder
Since updating to Lion, none of my image show their dimensions in Finder column view. I tried highlighting a file for a while or opening it with Preview, as suggested by this anser without success. Here is a screenshot to visualize my problem :
How can I see any file dimensions in Finder, like I did with Snow Leopard ?
I'm not sure about 10.6, but on 10.7 the dimensions are shown in information panels:
The Finder's information should be refreshing automatically and instantly as files and information is changing that is the goal and why Apple does not provide a "Refresh" option, although in practice things sometime don't work for whatever reason.
If the information is not automatically updating changes to files etc, it may be the result of a bug or Finder preferences corruption, or other corruption.
Make sure you are running the latest version of OS X, as the issue may be a bug that has been fixed already.
Additionally for folders where the contents are not updating properly it might be a good idea to try and remove the .DS_Store file for that directory, and see if that has an effect. (restarting the finder to verify)
The next option would be to reset the Finder's preferences. Try removing the the file named com.apple.finder.plist located at ~/Library/Preferences/com.apple.finder.plist (restarting the finder to verify)
If the problem is consistently occurring contact Apple and show them the issue and how to repeat it, you may have found a bug.
Best Answer
It looks like this has to do with Spotlight. Finder's knowledge of additional file information is integrated with Spotlight, disabling it, or adding locations to the privacy list will prevent Finder from reporting file information. This includes image dimensions.
If Finder is not reporting "More Info," make sure that directory is not blacklisted by Spotlight. In the screenshot above, anything found in the "Private" folder will show a "--" under the More Info section. This is by design.