# How do you calculate 83R + 57B + 139G to get a wavelength of the perceptual color? I started with a RGB value of R=140, G=196, b=57.       I am just not coming up with the way to do the calculation. I am taking a physics of light and color class.

Colors as perceived by us are dependent on the wavelengths of light that create the color. Some colors that we can identify are created by waves with a unique wavelength, for instance, it is possible to identify the wavelength of light that appears as red, blue or green. Other colors are an amalgamation of light waves of different wavelengths.

It is not possible to identify a single wavelength of light that appears the same color as that created by using an RGB value of {140, 196, 57}.

You may be able to identify a single wavelength of light that has a color similar to that produced by the combination of red, green and blue you have mentioned. This would involve trial and error, and you may have chosen a color that can be recreated with light of a single wavelength. Although it is not possible to identify one single wavelength of light that has the same color as that produced by any given combination of RGB because it is an amalgamation of light waves.