A cost effective multicolor sensor and related software achieves a spectral response that closely approximates an ideal photo response to measure optical measurement, for example photosynthetic photo flux density (PPFD). The spectra error of the sensor is smaller than that of the best commercially available sensor at a significantly reduced cost. The sensor may include an 8×2 array of filtered photodiodes and spectral photo sensors that are linearly combined with the appropriate mathematically determined coefficients to create a corrected spectral response curve that has a spectral error much smaller than the best commercial available sensors made by physical coating methods for the entire desired range.