For sorry, Watermarking is out of the exclusion
Our plugin uses .htaccess commands to watermark images
this way is very strong but its too difficult when you want to add special rules
The .htaccess file executed on your website server before your website (WordPress) start, so there is no way to tell .htaccess commands a lot of information about the requested images
We just can read (URL & Image name) so we choose to treat with image name
If your excluded images is fixed and not a lot then the previous way seems to be good for you
This post is deprecated, The watermarking feature can now be excluded as same as any other feature
How to exclude any image from watermarking?