This was my first major symptom, over two decades ago. Faces everywhere but worst in trees. Wood paneling, plaster walls and clouds were terrible to look at as well (try avoiding plaster walls, trees and clouds for a day). Needless to say it freaked me good. Interestingly and luckily - and hopefully in your case - this phase disappeared over time (a few years) and now what remains is bad static, tracers and after-images. For some reason, during this time, it seemed to help to say to myself what you have stated "this is only a perceptual thing" etc. Have some hope that this particular symptom (as well as all others according to some - I have not been so lucky) will likely disappear.