The irreducibility of phenomenal experiences does not refute physicalism. It’s quite a fascinating post that the way we perceive a tree which happens in the visible spectrum of light is it’s most accurate of such a depicted tree with all its foliage, branches etc.
Yet our vision has also a limit here as we do not have the sensory ability to see the roots of the tree at first instance. So trees are not concepts of ideas but actual real things. At least I think that’s what you’re getting at.
You also refer to meta cognitive processes such as where in the mind/brain this tree is being perceived which is undisclosed to us perhaps due to evolutionary efficiency of the way our brains are structured.
To answer your question I think brain processes and vision are interlinked and in constant interplay during visual stimuli presented to the senses. If you close your eyes whilst looking at the tree, the tree disappears. Perhaps a brain scan during such vision can interlace with the tree being viewed in the brain itself in real time or not.
The real issue for me is not with sensory inputs when it comes to physicalism but abstract ideas generated by minds such as math or our ability to compute in the form of mental arithmetic on the fly such as 7+7 etc.
These I believe are irreducible to physicalism but other sensory stuff may be such as the taste of sweetness.