Fast Rehalftoning and Interpolated Halftoning Algorithms with Flat LWO-Frequencey Response

|We present raster image processing algorithms for rehalftoning error di used halftones and producing interpolated error di used halftones. Rehalftoning converts a halftone created by one method into one created by another method. In interpolated halftoning, interpolation increases the image size before halftoning, e.g. for printing. Both rehalftoning and interpolated halftoning introduce blur and noise in the output image. To compensate for the blur, we use modi ed error di usion, which has a variable gain parameter to control the sharpness. We derive optimal formulas for the sharpness control parameter to make the overall frequency response at. The high-frequency noise is masked by error di usion. The proposed algorithms yield halftones of high delity at a low computational cost.