Digital color halftoning is the process of transforming continuous-tone color images into images with a limited number of colors. This chapter deals with color halftoning algorithms that have embedded within them a detailed spatiochromatic model for the human visual system (HVS). It discusses the use of color hardcopy and HVS models only with dispersed-dot halftoning algorithms. The chapter explains the use of these models to design screens that produce clustered-dot periodic textures. The HVS is responsible for mapping the physical color halftone image to the percept of a continuous-tone color image. Between the digital color halftone image and the HVS lies the physical printing mechanism, including the colorant and media. In monochrome halftoning, the HVS models that have been incorporated into halftoning algorithms have been limited to linear shift-invariant filters based on the contrast sensitivity function of the human viewer.