I understand I can get a color from wavelength but it's not true for the opposite direction. In case this picture would help.
To make this question simple, let's lighting and calibration aside to an optimized condition.
I wonder if there is any way to get intensity value of a certain spectral wavelength for given pixel of a common image. That is, Wavelength and rgb of a pixel are both known. Based on that, I want to compute intensity of the wavelength for the pixel.