Consider, for example, this page you are reading. There is no doubt that you are seeing a particular paper, and that you are seeing the words on the paper. The question is, how is the paper appearing to you and what it's relation to the way someone else might see it. While Broad dismissed the theory of perspectives and came up with a philosophical answer, I believe that there is still a base foundation for a theory of appearances in physics.
While I am not a physics expert I have a sufficient grasp of the concepts behind the reflection of light off of surfaces to formulate a rough theory of my own. Might I just state that I agree to a considerable degree with Chisholm viz. his analysis of the grammatical importance of the word ``appearance''. However, I believe that this fails to combine the physics with physiology and philosophy.
Consider the piece of paper mentioned above. If it is the case that the same piece of paper appears different between your perceiving it, and my perceiving it at the same moment, then this may be attributed to the way light reflects off of the paper. If there was no light source, we would have nothing to see! Further, the difference in perception has a great deal to do, not with perspectives, but with the way the light travels from the source and reflects off of the object. Remember Broads objection to perspectives: it is a prediction of how something is to look like based on your three-space position. It, however, doesn't consider the physics of electromagnetic radiation.
Electromagnetic radiation at such high frequencies, as light, is very reflective and absorbable. When we see something that is red, say a red balloon, we are not seeing the balloon at all. Rather, we are seeing the light energy (from a particlar light source) being absorbed by the chemical coating the balloon. What light is allowed to escape and be reflected is of a particular wavelength, which in this case is red. In effect, we never directly perceive the object we are looking at. All we perceive is a particular chemical and physical reaction of light energy. When the light energy reaches our eyes, we experience another electro-chemical reaction such that this light energy impresses upon us the object's image.
I also argue that we can never see, or conceptualise to any degree of reality, an object through the use of our imagination that which has not already been exposed to us. While it is true that I can picture a ``pink elephant'' in my head, or a ``yellow monkey'', I cannot see it as it actually would exist, simply because it does not exist. All that I, or anyone else, can do is combine the abstract concept of yellowness (the average of all objects labelled yellow which I have perceived) and a real picture (once again from memory) of a monkey. I attempt to overlay these two concepts from memory to formulate an approximate mental image similar to my understanding of this ficticious object.
While this is just a quick sketch of this theory, I do not presume that it is all encompassing of the different pitfalls awaiting. Further, there might be great objections from those defending the power of human imagination. But I would appeal to those defenders of human imagination to come up with a concept which is not comprised by a melange of previous experiences and perceptions from memory.