A calibration device receives at least a first multispectral measurement of: a first monochromatic signal taken at a first pixel location; a second multispectral measurement of a second monochromatic signal taken at a second pixel location; and a multiplicity of third multispectral measurements of a spatially distributed wide bandwidth dispersed spectrum, of a wide bandwidth signal, taken at a multiplicity of third pixel locations. The device relates known pixel values of wavelengths to pixel values of measured wavelengths. The device outputs spectrum wavelength and power calibration values for the multispectral imaging system, comprising at least a relation of: a first third pixel location to a first known wavelength; and a second third pixel location to a second known wavelength.