hello
I do it often (for network monitor policies) and it works quite fine (DLP v11.1.2) :
- add an exception in the policy
- select file name exclusion
- enter your name file (avoid as much as you can joker because it is sometimes interpreted as a caracter)
- save
Does your message still matching on this image or on something else ? If it still doesnt work for you, you can post some screen copy of your policy and incident then we can have a deeper look at it.
other suggestion for exception :
When you define an exception on an image take care to exclude only the matched component (upper part of exception definition) and not full message (this is the default value for file name exclusion).
If you are little bit paranoid, you can compund this exception rule using file size (to be sure it is your company logo) and file type (to be sure no one rename an excel file) , so it can avoid than some people knowing this exception name their file image001.jpg. if you are definitely ready to be mister paranoiac, you can have a look at the binary part of your file and select two different set of bytes in the middle of the file then create a custom script (yes guy i am paranoiac :) )