How to change opacity of header image

Hi, I am testing out the Bravada theme on a local install of WordPress and it’s looking great except that I can’t seem to figure out how to increase the brightness/opacity of the header media under Site Identity (ie. the image is too dark).

It looks like the setting is either opacity or rgba but I can’t seem to figure out which one or which portion of the css to modify. Does anyone know how to prevent the header image from getting darkened too much? Thank you in advance for any help you can provide! =)