I understand what you mean, the image editor in the Wordpress post editor. You want to have a certain text pre-filled into the field "Edit Image Title" so you don't have to paste it in each time. While this is possible it would be easier to just add that image title after the fact, when the page is being processed, instead of having that text there at the time when you edit or insert and picture.
Similar to this
http://forum.bytesforall.com/showthread.php?p=4791
Do you want to ADD to what WP already adds to the image title (usually the filename without the ending, i.e. "myimage" for myimage.gif) or replace what's there with "© My blog All rights Reserved".
Also, are these images going to be linked, will they have captions, or both? I guess a mixture of this, different for each image?
I'll update that other thread tomorrow with a solution for caption/links/nothing. Please remind me to post here too if I forget