The hybrid screen: improving the breed

Abstract

The hybrid screen is a halftoning method that generates stochastic dispersed dot textures in highlights and periodic clustered dot textures in midtones. Each tone level is sequentially designed from highlight to midtone by applying an iterative halftoning algorithm such as direct binary search (DBS). By allowing random seeding and swap-only DBS in a predefined core region within each microcell, we design each level while satisfying the stacking constraint and guaranteeing a smooth transition between different levels. This paper focuses on a number of enhancements to the original hybrid screen and their impacts on print quality. These include analytical determination of the human visual system filter in the spatial domain for DBS, multilevel screen design either by extending a bilevel screen or by directly generating a multilevel screen on the high resolution grid. Our results show that the multilevel screen design method has a direct impact on hybrid screen design parameters such as the optimal core size. We also extend the whole design process to color by jointly optimizing the color screens using color DBS. Our results demonstrate a significant improvement in the highlights over halftones generated by independently designed screen.

Structure-aware QR Code abstraction

“…According to [14,21], digital halftoning algorithms can be classified into three groups. The first group uses dithering [2,25], the second group employs neighborhood process [3,6,16,19,29], and the third group uses iterative algorithms [1,20].…”

Extrinsic Signature Embedding and Detection in Electrophotographic Halftoned Images Through Exposure Modulation

“…With laser EP printers, the overwhelming choice of halftoning algorithm is a screen-based algorithm that generates periodic, clustered dots. Algorithms, such as error diffusion or dot-diffusion [31], [32], that generate aperodic or stochastic, dispersed-dot textures are eschewed because of the complexity of their implementation and the fact that such textures cannot be stably printed with an EP marking process [33].…”

“…The design of a color, periodic, clustered-dot screen set requires the selection of a set of tile vectors, followed by the definition of rules for dot growth for each of the colorant screens [30], [33]. These choices are governed by many target-printer-specific factors, including the need to avoid moiré artifacts causing by beating of the periodic screens with residual periodicities in the process (cross-scan) direction due to imperfections in the rotating laser scanner mirror shown in Fig.…”

Binary text image file preprocessing to account for printer dot gain

“…Finally, we use the direct binary search (DBS) algorithm to find a locally optimum precompensated binary image. DBS has proven to be an effective tool in a variety of halftoning applications [3,6,7,[11][12][13][14][15][16]. To our knowledge, this is its first application to the optimization of printed text images.…”