My personal definition of consciousness is tied up with memory. What I mean by this is that you can only be conscious of potentially remembered perceptions and that you never remember things that you were not originally conscious of. Maybe the act of implanting the memory is somehow consciousness. Perhaps it's the data compression of the perception prior to storage- replacing the actual data of the perception with smaller links to previous perceptions, or something like that. Any filtering out of non-interesting data happens before this.

I like this definition, because it allows for the huge amount of unconscious signal processing in the brain that we are not aware of. For example, we don't remember the color left eye rod #12579 at such and such a time, but we do remember that there was an orange cat sitting on the stairs.

Anyway, so I think a lot of visual processing is unconscious and it should be no surprise that parts of it happen in different parts of the brain. I don't buy that they are necessarily detecting conscious perception, just some part of the image processing.