Pixelation…please bear with me…

I’ve searched the forums but not really found the right answer. Probably because I’m not a WP person and I’m clueless about all this. However, it’s my photos that are being uploaded and the admin doesn’t seem to be interested in resolving the issue so I’m going to ask and in the process, probably bring up a topic that’s been addressed before and drive people crazy by asking again.

The issue in a nutshell:

When photos are published you can click on a horizontally oriented photo to enlarge it and it looks fine…I don’t think it’s actually enlarged anymore on the screen than the original post.

With vertically oriented pictures they do get enlarged and basically it looks as if your seeing a 72dpi image enlarged to 200%. The images look like they’re made of legos.

What can I do to fix this since the admin isn’t interested in fixing it? I do have admin privileges but I don’t know the first thing about this stuff. I’m just a photographer that wants photos to look good.

Thanks for bearing with me if you can help. I’d love to learn this stuff in detail but I can barely find time away from the camera to be with my wife as it is.