Unfortunately as far as i know, You can only get Images Instead of Text only on the Themes where the Title is actually an image.

Sorry.

Hi Owen, Thanks.
I did a modified Aerial theme called areialredux, replacing the headline text with a logo image.
I noticed that shimray also did the same thing called aerialplusplus.
I see there is an upload field for the logo image on that themes admin panel  (screenshot).
I'm just wondering where that option on admin comes from.

Not Quite sure, I would image its a File in the Theme.

hello!!! Yeah that can e done. I think tat is in master pages. You have to edit the index and the general....forgot which lines exactly!

I'll try to re-phrase the question:

1) Where does >Admin >Edit theme get those options from?
  
Example:
- I create a theme based on the Club theme.
- The original Club theme uses a site title \ tagline.
- I edit the css and general.html/dndindex.html to replace the title with a logo image.

2) How do I add an 'Upload Logo' field to >Admin >Edit Theme if it's not already there in the original theme?

I can't figure out... Where does >Admin >Edit theme get those options from for each theme?

Can any theme developer help?
Where does >Admin >Appearance >Edit theme get those options from for each theme?

admin/theme/settings