How do you change red to blue?

Answer 1

It would be useful to know the context of this question. A red object can be painted blue. Red paint cannot really be turned into blue paint, although if you add enough blue to it you could get a very bluish purple. In terms of light radiation itself, there is such a thing as the blue Doppler shift, which you can get by moving toward the source of the radiation at high speed, but that is technically very difficult to do, and is of purely theoretical interest.

Answer 2

To change red to blue, you would need to mix red with a color that is opposite on the color wheel, which is blue. By gradually introducing blue pigment, you can shift the color from red to purple and then to blue. It is important to adjust the ratio of red and blue carefully to achieve the desired shade of blue.