A multilevel halftoning algorithm can be used to overcome some of the challenges of multi-channel printing. In this algorithm, each channel is processed so that it can be printed using multiple inks of approximately t...
详细信息
ISBN:
(纸本)9781479917655
A multilevel halftoning algorithm can be used to overcome some of the challenges of multi-channel printing. In this algorithm, each channel is processed so that it can be printed using multiple inks of approximately the same hue, achieving a single ink layer. The computation of the threshold values required for ink separation and dot gain compensation pose an interesting challenge. Since the dot gain depends on the specific combination of ink, paper and print resolution, compensating the original image for multilevel halftoning means expressing the dot gain of multiple inks of same hue in terms of the coverage of a single ink. The applicability of the proposed multilevel halftoning workflow is demonstrated using chromatic inks while avoiding dot overlap and accounting for dot gain. The results indicate that the multilevel halftoned image is visually improved in terms of graininess when compared to bi-level halftoned images.
Based on the human vision system (HVS), this paper introduces an error diffusion algorithm that produces higher visual quality results while preserving fine texture details and tone consistency present in the original...
详细信息
ISBN:
(纸本)9781479957521
Based on the human vision system (HVS), this paper introduces an error diffusion algorithm that produces higher visual quality results while preserving fine texture details and tone consistency present in the original images. We calculate the visual difference between the original and halftone images based on the HVS model. Then by compensating original images for visual difference, reconstructed continuous-tone images that respect the human vision characteristics are obtained. Besides, we use the adaptive median filter to remove noises and preserve sharpness in the reconstructed images. Finally, Floyd-Steinberg E-D using threshold modulation is adopted to get the halftoning results. Multiple experiments show that our method outperforms the existing state-of-art halftoning algorithms and presents visually pleasing results with both fine texture details and clear lines especially in the weak texture and dark tone regions. Meanwhile, our method is much faster due to its simple processing procedure. Combined good visual properties with fast speed, our method can be applicable in most real-world applications.
Conventional digital halftoning approaches function by modulating either the dot size [amplitude modulation (AM)] or the dot density [frequency modulation (FM)]. Generally, AM halftoning methods have the advantage of ...
详细信息
Conventional digital halftoning approaches function by modulating either the dot size [amplitude modulation (AM)] or the dot density [frequency modulation (FM)]. Generally, AM halftoning methods have the advantage of low computation and good print stability, while FM halftoning methods typically have higher spatial resolution and resistance to moire artifacts. In this paper, we present a new class of AM/FM halftoning algorithms that simultaneously modulate the dot size and density. The major advantages of AM/FM halftoning are better stability than FM methods through the formation of larger dot clusters;better moire resistance than AM methods through irregular dot placement;and improved quality through systematic optimization of the dot size and dot density at each gray level. We present a general method for optimizing the AM/FM method for specific printers, and we apply this method to an electrophotographic printer using pulse width modulation technology. (C) 2004 SPIE and IST.
We present a new class of dithering algorithms for black and white (b/w) images. The basic idea behind our technique is to divide the image into small blocks and minimize the distortion between the original continuous...
详细信息
We present a new class of dithering algorithms for black and white (b/w) images. The basic idea behind our technique is to divide the image into small blocks and minimize the distortion between the original continuous-tone image and its low-pass-filtered halftone. This corresponds to a quadratic programming problem with linear constraints which is solved via standard optimization techniques. Examples of b/w halftone images using our technique are compared to halftones obtained via existing dithering algorithms.
暂无评论