Are there only seven colours of light?
These seven colours are not separate (distinct) from each other but from a continuum. It depends on you. One can have some more colours like Bluish-Green that is distinct from blue as well as green. Brown is not a colour on this VIBGYOR but human eye registers as distinct. A better way is ‘colorimetry’ where each colour is represented as a point on X-Y plot. In this Red is plotted on X axis and Green on Y axis each on a scale of 0 to 1. By means of three pure colour filters (R, G, B), other colours are derived or generated. R+G+B = 1. B = 1 – (R+G). So the B (Blue) is the line connecting points G (0,1) and R (1,0). In the same system a computer can generate more than 30,000 colours including pure black and white (gray levels).
