SELF-MODULATED HALFTONES

We propose an analytic method to overcome the trade-off between the spatial and tonal resolution of traditional clustered dot halftones. Continuous phase modulated halftones that allow variations in screen frequency in different regions of the printed image are employed and halftone screen frequency is varied according to the frequency content of the image to be halftoned. The method, which we term self-modulated halftoning, has a computational complexity similar to screening and is significantly lower than that of other adaptive methods that have previously been used to address the same problem. We demonstrate the experimental performance of selfmodulated halftones and discuss its capabilities and limitations. Index Terms — Digital halftoning, frequency modulation, gray tone vs. spatial resolution trade-off 1