The initial string is [image:salmon-v5-09-14-2011.jpg]
I would like to capture the text \"salmon-v5-09-14-2011.jpg\" and used GSkinner\'s RegEx Tool
You have the correct regex only the tool you're using is highlighting the entire match and not just your capture group. Hover over the match and see what "group 1" actually is.
If you want a slightly more robust regex you could try :([^\]]+)
which will allow for any characters other than ]
to appear in the file name portion.