A computer implemented method, comprising: (a) obtaining, using a processor, spectral reflectance data measured at multiple angles using a goniospectrophotometric device from at least one calibration panel; (b) calculating, using a processor, Fourier coefficients of a phase function using an orientation distribution function; (c) calculating, using a processor, a plurality of radiative transfer parameters, namely attenuation and orientation parameters and an anisotropic factor, from the spectral reflectance data obtained from the at least one calibration panel; (d) solving, using a processor, a radiative transfer equation across all angles; (e) calculating, using a processor, a reflectance from the radiative transfer equation; (f) repeating of steps (b) to (e) for each measured wavelength; (g) obtaining, using a processor, spectral reflectance data measured at multiple angles using the goniospectrophotometric device from a target coating; (h) selecting a list of possible toners; (i) calculating, using the processor, a reflectance that approximates the spectral reflectance data obtained in step (g), wherein calculating comprises performing a calculation using a radiative transfer equation inputting the attenuation parameters calculated in step (c); (j) generating, using the processor and based on the calculated reflectance data a coating formulation that is the same in appearance to the target coating, wherein the coating formulation utilizes one or more of the possible toners; (k) changing the coating formulation by removing at least one toner from the coating formulation; and (l) optimizing, using a processor, the coating formulation. (a) obtaining, using a processor, spectral reflectance data measured at multiple angles using a goniospectrophotometric device from at least one calibration panel; (b) calculating, using a processor, Fourier coefficients of a phase function using an orientation distribution function; (c) calculating, using a processor, a plurality of radiative transfer parameters, namely attenuation and orientation parameters and an anisotropic factor, from the spectral reflectance data obtained from the at least one calibration panel; (d) solving, using a processor, a radiative transfer equation across all angles; (e) calculating, using a processor, a reflectance from the radiative transfer equation; (f) repeating of steps (b) to (e) for each measured wavelength; (g) obtaining, using a processor, spectral reflectance data measured at multiple angles using the goniospectrophotometric device from a target coating; (h) selecting a list of possible toners; (i) calculating, using the processor, a reflectance that approximates the spectral reflectance data obtained in step (g), wherein calculating comprises performing a calculation using a radiative transfer equation inputting the attenuation parameters calculated in step (c); (j) generating, using the processor and based on the calculated reflectance data a coating formulation that is the same in appearance to the target coating, wherein the coating formulation utilizes one or more of the possible toners; (k) changing the coating formulation by removing at least one toner from the coating formulation; and (l) optimizing, using a processor, the coating formulation.