The Research Of The Amplitude Modulation/Frequency Modulation In The Digital Halftoning Technology

The digital halftoning is a pivotal technology, which can realize the reproductionoptimization of the image on the binary output devices. The amplitudemodulation/frequency modulation halftoning is a common screening method. It can getmore stability than frequency modulation through the formation of larger dot clusters.Meanwhile, the irregular dot placement can reduce the moiré artifacts in amplitudemodulation. This paper focused on the parameter optimization design and theimprovement effects of dynamic error diffusion to the amplitude modulation/frequencymodulation halftoning for the laser printer which has low resolution.During the realization processing of amplitude modulation/frequency modulationhalftoning, this paper presents a new conception of the cost function as a criterion,which can compensate the output tone and the print distortion to get the optimal dotsize and dot density. And the multiresolution iterative coordinate decent algorithm isproposed to consistently minimize the cost function. Considering the printer usingpulse width modulation, the quantization threshold and the position of the pixel pairsin the traditional error diffusion are redesigned. The smoothly transition betweenadjacent tones can be realized through dithering the dot size using a second level oferror diffusion.Based on the amelioration to the structure and the direction of the error weights inthe error filter, we introduce the dynamic error diffusion to the amplitudemodulation/frequency modulation halftoning algorithm. This paper presents theadaptive error diffusion algorithm based on the least mean square, the area distancemodel algorithm based on energy function curvature and the dynamic error diffusionalgorithm based on edge detection. We implement those dynamic algorithms toconsider the relationship between the dots' similarity and error diffusion, which isusually neglected in standard error diffusion. The compensation precision of errordiffusion is advanced, which causes the image more explicit and shows obvious tonecontinuity. The printout using the dynamic error diffusion shows that amplitudemodulation/frequency modulation halftoning has better reappearance ability.