A method selects a phase shift profile to be applied to a programmable optical phase shift modulator having an array of pixels. A base stepped phase shift profile for the modulator is selected such that when applied to the modulator, the base stepped phase shift profile allows the modulator to function as a blazed grating steering an optical beam through a prescribed angle. The base stepped phase shift profile has a plurality of segments each extending over a given number of the pixels defining a linear array of pixels. Each segment has first and last pixels in the linear array of pixels. Variations in minimum and maximum luminosity levels among the segments of the base stepped phase shift profile are reduced so that any changes to a slope of each segment arising from reducing the variations in the minimum and maximum luminosity level is maintained below a given amount.