It's a funny, though in retrospect unsurprising, coincidence that you're using a light-related metaphor. For a while, I was intending to write about "phenomenal transparency", especially as used by Thomas Metzinger. He quotes an early paper by the philosopher G.E. Moore, who spoke of the fact that while we can see e.g. the color blue, we cannot see what it is that makes it blue.

And in general, that which makes the sensation of blue a mental fact seems to escape us; it seems, if I may use a metaphor, to be transparent - we look through it and see nothing but the blue; we may be convinced that there is something, but what it is no philosopher, I think, has yet clearly recognized.

Metzinger notes that the most philosophers now use "transparency" to mean that the "content properties" of our mental states are available for introspection, but not their "vehicle properties". However, he finds this definition unsatisfactory and offers his own:

Transparency in this sense is a property of active mental representations already satisfying the minimally sufficient constraints for conscious experience to occur. [...] The second defining characteristic postulates that what makes them transparent is attentional unavailability of earlier processing stages for introspection. [...] What is attention? In short, attention is a form of nonconceptual metarepresentation operating on certain parts of the currently active, internal model of reality. It "highlights" these parts, because it is a process of subsymbolic resource allocation. The earlier the processing stages, the more aspects of the internal construction process leading to the final, explicit and disambiguated phenomenal content that are available for introspective attention, the more will the system be able to recognize these phenomenal states as internal, self-generated constructs. Full transparency means full attentional unavailability of earlier processing stages. Degrees of opacity comes as degrees of attentional availability.

Definition 2 For any phenomenal state, the degree of phenomenal transparency is inversely proportional to the introspective degree of attentional availability of earlier processing stages.

In other words, the processes in our mind that we are unable to perceive, we take as givens. Were we able to perceive e.g. the way our visual cortex constructed images, or the way our cognitive subsystems constructed beliefs, we'd realize them to be constructions and not take them so easily for granted.

I've been meaning to write more about this, but have never gotten around it.