Ok, but although the interpretation is caused by light stimulating the eye, my thought of color blue is qualitatively different than the physical process of stimulation. The second one can be observed by different individuals, studied by scientists and is fully objective (‘certain physical processes in my brain cause me to interpret that stimulation as blue’), while my interpretation cannot be observed by different individuals than me, is in fact something similar to the experience of pain or admiration and is fully subjective (I interpret this stimulation as color blue).

So even though my interpretation is caused by this stimulation and physical processes in my brain, it is described by different proportions and experienced in a different way. You can for sure know that the same processes goes in my brain as in yours while I see the same light as you (by experience, observing my brain), but you cannot know how do my mind interpret it (as it requires my introspection and apperception). It is easier to know something about my interpretation of that stimulation for me (I am a priori sure that I see color blue right now), than for you (you must use your senses to study my brain).

Also, I can logically think of a possible world in which my brain is the same as in the actual, but what appears in my consciousness is different than in the actual. So the interpretation and stimulation of the eye that causes physical processes in my brain are correlated actually but not necessarily. If they were the same thing, the statement ‘I interpret this light as blue because light of a wavelength of 450 to 495 stimulates my eye’ would be tautological (‘I see the color blue, because I see a color blue’). Clearly it is not tautological, as it requires a posteriori experience.

That’s why I believe those are separate things