My dear,
I think the most elegant way to remove multiple files type is using what is called brace expansion.
How does brace expansion work?
Brace expansion allows you to create multiple strings from patterns within a brace, where each pattern is separated by a comma. For instance, the command
echo Front-{A,B,C}-Back
will yield
Front-A-Back Front-B-Back Front-C-Back
Simple like that :) You can also expand a range of integers using the following notation
echo {001..15}
How to use brace expansion to solve your problem?
Try it:
tar --exclude={'*.jpg','*.png','*.bmp','*.gif'} -cvf tar-filename.tar folder
If you want to check out what is going on, just echo this last command and you will notice that it produces
tar --exclude=*.jpg --exclude=*.png --exclude=*.bmp --exclude=*.gif -cvf tar-filename.tar folder
Both ways are correct, but mine is much more readable and compact :)
