I can’t figure this out just yet, but I haven’t had a lot of time to figure it out either. It looks like the option to insert a thumbnail is broken in the latest release of WordPress. (see bottom of this post. I did figure it out)
The thumbnail creation buttons are greyed out. (click to see full image)
I go to insert a picture into a post, and I get the screen with information about the picture I just uploaded. The option buttons allowing me to use a thumbnail-sized version of the picture are greyed out, however. The picture inserted into this post is not a thumbnail, but rather a full-size, scaled down by the browser, not the server.
Since this site is currently hosted out of my own basement, I need to conserve bandwidth. I have a cap on my server’s upload speeds, so ultimately not being able to use thumbnails is going to hurt the end user; the site will just take forever to load.
Now, I’ve gotten some hints that this is an indication that I am missing GD in my Apache installation. It doesn’t show up in my phpinfo() dump, so that’s the first thing I’m going to try. I will post back when I’ve got it figured out.
EDIT: Well, I figured out how to install GD; a bit of Googling around found this. It seems to be a bit dated; also, I am using PHP5, not PHP4. Issuing the command “apt-cache search gd” showed me all of the Debian packages with “gd” in the name; the one I want is “php5-gd – GD module for php5″. I ran “apt-get install php5-gd” to install the package. I restarted Apache by issuing the command “apache2ctl restart”, and the option buttons were enabled. Mystery solved!