The colour of light is determined by its 

Amplitude is used in the determination of intensity not in colour of light. When the light wave passes through a denser medium the colour remains the same while the speed decreases. We have studied that the colour is caused by the absorption of a specific wavelength The colour of light is determined by the wavelength of light.

 we know that frequency remains constant when the light travels through different mediums so the energy will also remain constant . Hence the energy of light and frequency is not used in determination of the colour of light.

so colour depends only on wavelength