1. A digital to analog converter array comprising: a plurality of pixels arranged in an array and independently addressable to selectively modulate light; a digital counter which generates a sequence of numbers in digital form; an analog signal source which generates an analog signal that corresponds the sequence generated by the digital counter; and a plurality of array elements which control the pixels, each element comprising: a digital memory register holding at least one input number, a comparator which generates an enabling signal responsive to a comparison between the number in the sequence and the input number; and a sample and hold circuit which samples the value of the analog signal, responsive to said enabling signal, and sets an output voltage controlling a pixel to said value, wherein the array is configured so that the comparators in all the array elements compare the number in the sequence to the input numbers held in said array elements substantially simultaneously.