The hybrid screen leverages two halftoning techniques, screening and direct binary search (DBS), to achieve the better quality of the halftoned images, and to enable the algorithm to be integrated into low-cost printers with limited computational resources. This work proposes a complete hybrid screen design method for multilevel output with unequal resolution printing pixels in a laser electrophotographic system. Because of the unstable rendering output of the electrophotographic process, we adopt a clustered- dot screen in our work. We also use the supercell approach to solve the trade-off between screen frequency and the effective number of quantization levels that is inherent to a cluster-dot screen. Moreover, we use subpixel modeling to simulate the unequal resolution printing pixels and multilevel output. This method is well-suited to development of halftoning algorithms for systems with unequal resolution. We also explore several design rules to evaluate the impact on printing quality.
In this paper, we propose a novel halftoning method that we call Ink-Saving, Single-Frequency, Single-Angle, Multi-Drop (IS-SF-SA-MD) halftoning. The application target for our algorithm is high-volume production ink-jet printing in which the user will value a reduction in ink usage. Unlike commercial offset printing in which fourcolorant printing is achieved by rotating a single screen to four different angles, our method uses a single frequency screen at a single angle, and depends on accurate registration between colorant planes to minimize dot-overlap especially between the black (K) colorant and the other colorants (C, M, and Y). To increase the number of graylevels for each colorant, we exploit the multidrop capabilities of the target writing system. We also use the hybrid screening method to yield improved halftone texture in the highlights and shadows.
Digital Watermarking of printed images is an important capability for many applications. Visually detecting the watermark through, e.g. UV illumination, enables the watermark use in uncontrolled environments. In our previous work, UV watermarking was proposed for in dispersed dot scenarios (assuming the use of standard colorants). This talk describes the generalization of that concept to clustered dot scenarios thereby allowing the creation on standard printing equipment, such as offset or xerographic printing.
In this paper, we propose a halftoning method with Neugebauer Primary Area Coverage (NPAC) direct binary search (DBS), with the optimized human visual system (HVS) model, we are able obtain homogeneous and smooth hafltone colored image. The halftoning is based on separating the colored image represented in Neugebauer Primary in three channels based on human visual system, with swap-only DBS, we arrange the dots to bring the error metric to its minimum and the optimized halftone image is obtained. The separation of chrominance HVS filters between red-green and blue-yellow channels allows us to represent HVS more accurately. Color halftone images generated using this method and method of using combined chrominance filter is compared.
The conventional color halftoning method for laser printer is based on periodic clustered-dot halftoning screen, which visible moire and rosette artifacts may appear. In this paper, the first two color aperiodic, clustered-dot halftoning algorithms, NPAC-MS-MP-CLU-DBS and PARAWACS-MS-MP-CLU-DBS, are introduced, which have the inherent stability during the printing process to resist misregistration and the potential to avoid moire and rosette for the aperiodic property. Besides, the color management pipeline for halftoning algorithms based on NPAC (Neugebauer Primaries area coverages) also be introduced in this paper.
3D printing is becoming increasingly popular around the world today. By utilizing 3D printing technology, customized products can be manufactured much more quickly and efficiently with much less cost. However, 3D printing still suffers from low quality surface reproduction compared with 2D printing. One effective approach to improve it is to develop an advanced halftoning algorithm for 3D printing. In this paper, a novel 3D DBS (Direct Binary Search) halftoning algorithm that can cooperate with current 3D printing technology is proposed which can generate high quality surface reproduction.