1. A computer-implemented method for generating a halftone image using a parametrically controlled spot function on an irregular halftone grid, comprising: generating a triangle tessellation from a set of input points arranged in an irregular grid; identifying encompassing triangles, which each encompass at least one pixel; determining distances from a given pixel to each side of the encompassing triangle in which the pixel is located; for each pixel, executing the spot function using the determined distances to generate an output spot function value for each pixel; and generating a halftone image using the output spot function values.