You cannot just assign to a field that is defined as one type with a value of a completely different type. You’ve got a field of type “Vignette” (postprocessing class) and you want to assign a bool (yes/no, true/false). That makes no sense at all. The error clearly tells you this so I’m not sure what your post is asking.
Doing “_vignette ? 1 : 0” will just indicate if that field has a reference to a class or not.
btw, here’s how to post code on the forums: Using code tags properly