How to get the wavelength of a pixel using RGB?

Question

I have a project that would classify the color of a pixel. Whether it is red,violet, orange or simply any color in the color wheel. I know that there are over 16 million color combination for pixels. But I was able to read a web page that says its possible for me to do my project using the wavelengths of color. Please give me the formula to compute for the wavelength using RGB values. Thanks!

Answer 1

A pure color has a wavelength (any single color LED will have a specific wavelength). Red, green and blue each have a range of wavelength. However, when you make an RGB color, you add these wavelengths together, which will NOT give you a new wavelength. The eye can't distinguish a yellow composed of one wavelength from that of adding red and green (just how the eye works). I'd recommend reading up on color theory

http://en.wikipedia.org/wiki/RGB_color_model

Answer 2

Well RGB for a monitor maps to 3 independant levels of Red Green and Blue light, so there are (mostly) 3 distinct wavelengths present of any one percieved colour.

BUT If you can convert your RGB colour value to its equivilent HSL, the H part (Hue) is the dominant colour in so far as wavelength goes if you are prepared to ignore the saturation (think of it as whiteness).

Based on that you could approximate the dominante wavelength of a colour based on its H value.

Red light is roughly 630–740nm wavelength, Violet is roughly 380–450nm.