Apparatus and methods for flexible digital halftoning are provided in which
novel pattern choices are allowed by not restricting the basic halftone patterns
to grow sequentially. Rather, positions in a threshold array allow multiple transitions
between on (i.e., printed with toner/ink) and off (not printed) as a function of
the input value at the corresponding position. In one embodiment, multiple threshold
matrices are employed and the output decision is a vote (e.g., exclusive OR) of
the outputs of the individual threshold matrices. In another embodiment, each position
contains an arbitrary bit vector to express the output for each input. In yet another
embodiment, space efficiency may be achieved by sorting the arbitrary bit vectors
into collections of adjacent decisions for a given input value, such as into bytes.