Methods are provided for controlling a lighting device with light-channels to produce illumination based on a reference spectral power distribution (SPD). The method comprises: determining first adjustments of the light-channels for minimizing first spectral deviation between a first calculated SPD and the reference SPD, the first calculated SPD depending on predefined SPDs of the light-channels and the first adjustments; inducing the light-channels to emit lights based on the first adjustments; receiving sensor signals from a colour sensor representing colour coordinates of a mixture of lights produced by the light mixer as a result of mixing the lights emitted by the light-channels; performing an optimization process producing second adjustments for minimizing a colour deviation betweencolour coordinates of reference and the colour coordinates of the mixture of lights; and inducing the light-channels to emit lights based on second adjustments. Controllers and computer programs suitable for performing such methods are also provided.