Do not try to characterize light by it's colour. Colour is something that is defined only in vacuum! Light is characterized by it's wavelength or frequency, one is enough. You additionally have to have the knowledge of the refractive index though. So you are right about how the wavelength is changing but the frequency stays constant.

To the question what we will see as an observer: We would see red light. Because when the light quits the glass, the wavelength and frequency will experience the reverse change than as when they entered. You would see the exact same light that entered the glass which was described by you as red.

An interesting question though is what would we see if we were able to put our eyes INTO the glass, so that the light is not transformed back to it's initial state. Well then SamRoelants pointed out what we would see.

Do not try to characterize light by it's colour. Colour is something that is defined only in vacuum! Light is characterized by it's wavelength or frequency, one is enough. You additionally have to have the knowledge of the refractive index though. So you are right about how the wavelength is changing but the frequency stays constant.

To the question what we will see as an observer: We would see red light. Because when the light quits the glass, the wavelength will experience the reverse change than as when it entered. You would see the exact same light that entered the glass which was described by you as red.

An interesting question though is what would we see if we were able to put our eyes INTO the glass, so that the light is not transformed back to it's initial state. Well then SamRoelants pointed out what we would see.