There are many definitions of qualia, which have changed over time.
One of the simpler, broader definitions is:
"The 'what it is like' character of mental states. The way it feels to have mental states such as pain, seeing red, smelling a rose, etc."
Examples of qualia include the pain of a headache, the taste of wine, or the perceived redness of an evening sky.
I believe that there are two types of qualia.
The first type only conveys information.
For example a black and white image or the sensation of touch or a pure tone (without harmonics)
The second type conveys a pleasant or unpleasant sensation.
For example a beautiful color image of a rainbow or the taste of something sweet.
The first type gives us information that we can use to make decisions toward achieving our goals (for example to satisfy our curiosity)
The second type becomes a goal unto itself.
Imagine a computer capable of recognizing shapes and objects and of recognizing actions performed by thoses objects and capable of creating and analyzing complex simulations.
Clearly it is aware of and perceiving some sort of sensation which conveys Information to it.
But it is just information.
Until we figure out how the second type of qualia works our computers will only be able to experience the first type of qualia
Yellow = pleasant white
Red = pleasant grey
Blue = pleasant black
Orange = red + yellow
Purple = red + blue
Green = blue + yellow
Salty = information
MSG = information
Sweet = pleasant
Bitter = unpleasant
Sour = ?
Hot = ?
Fat = ?
Touch = infinitesimal pressure
Pressure = information
Pain = unpleasant pressure
Pleasure = pleasant pressure
Temperature = information (obsolete)
Hot = unpleasant temp
Warm = pleasant temp
Cold = unpleasant temp
Tone = information
Harmonics = pleasant tone