Hi everybody, I'm looking for an answer I didn't found on my books or internet. I'm trying to compute the XYZ and luminous flux from spectral data of a lightsource (taken from argyll and a colormunki). Since I cannot compute true integrales, I'm using sum products: every radiant intensity beeing multiplied with color matching functions of the same wavelenght. Then, all products are summed. My problem is that the sum product will clearly depends on the wavelenght interval. I'll get higher XYZ if my wavelenght intervall is 5nm than with 10nm. Then how could I get normalized luminance from that? Sorry if this seamed to be a stupid question, Thanks by advance, Matthieu DUBAIL www.presse-bouton.com