Inverse Qualia is a scenario which may be possible or impossible.

Qualia are the subjective or qualitative properties of experiences. Examples of qualia are the pain of a headache, the taste of wine, the experience of taking a recreational drug, or the perceived redness of an evening sky. It is the variety of ways things seem to us. The way it feels to have mental states such as pain, seeing red, smelling a rose, etc."

Another way of defining qualia is as "raw feels." A raw feel is a perception in and of itself, considered entirely in isolation from any effect it might have on behavior and behavioral disposition.

Feelings and experiences vary widely. For example, I run my fingers over sandpaper, smell a skunk, feel a sharp pain in my finger, seem to see bright purple, become extremely angry. In each of these cases, I am the subject of a mental state with a very distinctive subjective character. There is something it is like for me to undergo each state, some phenomenology that it has.

Qualia are often referred to as the phenomenal properties of experience.

"[i]f we acknowledge that a physical theory of mind must account for the subjective character of experience, we must admit that no presently available conception gives us a clue how this could be done."

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Inverse Qualia

Imagine that we wake up one morning and find that for some unknown reason all the colors in the world have been inverted. Furthermore, we discover that no physical changes have occurred in our brains or bodies that would explain this phenomenon.

Inverse Qualia represents the recognizable qualitative characters of the given, which are repeated in different experiences, and are thus a sort of universals. It's a universal, in the sense of being recognized from one to another experience, the Qualias are distinguished from the properties of objects. The Qualia is directly intuited, given, and is not the subject of any possible error because it is purely subjective. In respect, it is a scenario which may be possible or impossible.

Metaphysical identity holds of necessity.
If something is possibly false, it is not necessary.
It is conceivable that qualia could have a different relationship to physical brain-states.
If it is conceivable, then it is possible.
Since it is possible for qualia to have a different relationship with physical brain-states, they cannot be identical to brain states (by 1).
Therefore, qualia are non-physical.

Inverted Qualia deals with conceivability and possibility. However, the idea of an Inverse Qualia is undetectable in practice.