I'm pretty sure others have better answers than I do on whether objects we appreciate and describe as beautiful have intrinsic quality or if the entirety of the beauty exists only in the observer. I believe that there is an interplay between observer and object but I don't think I could prove it to you. However, if there was a pill that made me believe that something I previously thought was terrible and ugly was the most beautiful thing I had seen, that would not convince me that objects had no inherent beauty, just that the my brain was easily manipulated.
Ha, right, perhaps I hallucinated separately the image and the emotion that it is beautiful. My guess (just a guess) is that the images were themselves generated by the parts of the brain that register beauty, and so were beautiful by definition. If that's not true, I suspect that if you sat a large sample of people to look at these images, most would agree they were beautiful.