Binary Halftone Research Articles

Taming Reversible Halftoning Via Predictive Luminance.

Traditional halftoning usually drops colors when dithering images with binary dots, which makes it difficult to recover the original color information. We proposed a novel halftoning technique that converts a color image into a binary halftone with full restorability to its original version. Our novel base halftoning technique consists of two convolutional neural networks (CNNs) to produce the reversible halftone patterns, and a noise incentive block (NIB) to mitigate the flatness degradation issue of CNNs. Furthermore, to tackle the conflicts between the blue-noise quality and restoration accuracy in our novel base method, we proposed a predictor-embedded approach to offload predictable information from the network, which in our case is the luminance information resembling from the halftone pattern. Such an approach allows the network to gain more flexibility to produce halftones with better blue-noise quality without compromising the restoration quality. Detailed studies on the multiple-stage training method and loss weightings have been conducted. We have compared our predictor-embedded method and our novel method regarding spectrum analysis on halftone, halftone accuracy, restoration accuracy, and the data embedding studies. Our entropy evaluation evidences our halftone contains less encoding information than our novel base method. The experiments show our predictor-embedded method gains more flexibility to improve the blue-noise quality of halftones and maintains a comparable restoration quality with a higher tolerance for disturbances.

Towards High-Resolution Copy-Evident Ceramic Tiles: A Deep Learning Framework for Halftoning and Watermarking

Ceramic art is essential in interior design and decoration, and making exquisite ceramic tiles imposes strict requirements for inkjet printing technology. High-resolution ceramic tiles are often produced through inkjet printing, in which the input images are converted into a halftone format. However, traditional binary halftoning techniques cannot produce high-resolution images for the ensuing printing process. Given that the processes of inkjet printing and high-temperature firing of ceramic tiles are a highly complex nonlinear system, and existing halftoning methods pose intractable problems, including inconsistent textures and color deviations. Based on a modified U-Net model and a modified error diffusion algorithm, we propose a multilevel halftoning method, which is capable of converting color-separation images of ceramic tiles into high-resolution halftone images. To deter copyright infringement, we further apply an ad hoc invisible watermarking method for halftone images. In this paper, we propose a four-stage framework: (1) A self-built dataset is used to solve non-convergence and overfitting problems caused by the unbalanced samples and non-uniqueness of halftone images. (2) A modified U-Net model is trained on the self-built dataset and applied to the ceramic-tile images. (3) An improved error diffusion algorithm is used to calibrate and convert the predicted continuous-tone transition images into multilevel halftone images for inkjet printing. (4) A invisible and robust watermark is embedding algorithm towards halftone images is proposed for copyright protection. Experimental results show that our methodology is effective for performing the color-to-halftone transformation and identifying the copyright.

Hiding color watermarks in halftone images using maximum-similarity binary patterns

This paper presents a halftoning-based watermarking method that enables the embedding of a color image into binary black-and-white images. To maintain the quality of halftone images, the method maps watermarks to halftone channels using homogeneous dot patterns. These patterns use a different binary texture arrangement to embed the watermark. To prevent a degradation of the host image, a maximization problem is solved to reduce the associated noise. The objective function of this maximization problem is the binary similarity measure between the original binary halftone and a set of randomly generated patterns. This optimization problem needs to be solved for each dot pattern, resulting in processing overhead and a long running time. To overcome this restriction, parallel computing techniques are used to decrease the processing time. More specifically, the method is tested using a CUDA-based parallel implementation, running on GPUs. The proposed technique produces results with high visual quality and acceptable processing time.

Reversible Data Hiding and Reversible Authentication Watermarking for Binary Images DOI: 10.14209/jcis.2008.4

Data hiding is a technique used to embed a sequence of bits in a host image with small visual deterioration and the means to extract it afterwards. Reversible data hiding allows, in addition, recovering the original cover-image exactly. Several reversible data hiding techniques have been developed but very few of them are appropriate for binary images. This paper proposes a reversible data hiding technique for binary images. This technique uses the Golomb code to compress prediction errors of low-visibility pixels, using its neighborhood as side information, to obtain the space to store the hidden data. The proposed technique is then used to reversibly authenticate binary images, including texts, drawings and halftones. All binary images we tested could be authenticated using the proposed technique, except unrealistically small or random images.

Novel Evaluation of Digital Halftone Image Qualities by Psychological Analysis

Monochrome binary halftone images express multiple levels with halftones produced by distributing black and white pixels. In this paper, for the subjective evaluation of halftone qualities, binary halftone images are considered as pointillistic images of visible black-and-white pixels. Visual impressions given by the pixel distribution are measured by the semantic differential (SD) method in a psychological manner. An experiment for measuring subjective impressions of subjects by using selected 30 SD items was conducted on several binary halftone images that were produced by three kinds of the typical halftoning methods: two error-diffusion methods and a kind of random dither method. The sample data are analyzed statistically by factor analysis. As a result, two common factors are found out and interpreted as the sensitivity factor and the activity factor, respectively. Also, the result of variance analysis demonstrates that the two common factors are able to describe the difference among the three halftoning methods.

Feature-preserving multilevel halftoning algorithm

Conventional threshold decomposition-based multilevel halftoning algorithms decompose an input image into layers, halftone each one of them with a binary halftoning algorithm, and combine their binary halftones to produce the final multilevel halftone. As layers are handled one by one subject to a stacking constraint, darker pixels in the final multilevel output are positioned first, which makes it difficult for the algorithms to preserve bright spatial features. This issue is addressed and a solution to eliminate this bias is proposed. Simulation result shows that the proposed method can provide an output of better quality as compared with conventional threshold decomposition-based algorithms both subjectively and objectively.

Binary grayscale halftone pattern generation using binary artificial bee colony (bABC)

In grayscale context, digital halftoning can be considered as binary pattern generation task where 0- and 1-valued pixels represent black and white, respectively. This paper presents application of artificial bee colony (ABC) in its modified binary form called binary ABC (bABC) toward generation of optimized binary halftone patterns. The human visual system incorporated cost function formulation addresses the tonal and structural parity between the original and halftone images along with pleasant halftone appearance. A pattern look-up table (p-LUT) approach is investigated including edge enhancement in halftone images. The results are presented pictorially and evaluated objectively. Comparison between the presented method and established halftoning techniques is also drawn to judge the potential of the presented bABC generated p-LUT approach. The pictorial presentations as well as objective evaluation show that the presented method may be potentially useful in the field of digital halftoning.

Towards optimized binary pattern generation for grayscale digital halftoning: A binary particle swarm optimization (BPSO) approach

Grayscale digital halftoning produces bi-level representation of original continuous tone images. This process plays pivotal role for devices like printers, plasma panels, LCD displays, etc. The bi-level images can be considered as binary images where ‘0’ and ‘1’ correspond to black and white, respectively. This paper investigates potential of binary particle swarm optimization (BPSO) to generate faithful binary halftone patterns. The cost function addresses important characteristics of original images and pleasant visual appearance of halftone images. The paper also shows the application of pattern look-up-table (p-LUT) approach to address the high processing time of BPSO optimization and simple gradient-based edge enhancement for improved edge retention. Results are evaluated subjectively by statistical measures and psychovisual test. Results are evaluated objectively using image quality evaluation metrics as well. The comparisons with state-of-the-art techniques are also drawn. The evaluation results along with the comparisons show the competitive potential of the presented technique.

Alleviating Dirty-Window Effect in Medium Frame-Rate Binary Video Halftones

A video display device having a lower number of bits per pixel than that required by the video to be displayed quantizes the video prior to its display. Halftoning can perform this quantization while attempting to reduce the visibility of certain quantization artifacts. Quantization artifacts are, nevertheless, not eliminated. A temporal artifact known as dirty-window effect (DWE) can be commonly observed in medium frame-rate binary video halftones. In this paper, we propose video halftone enhancement algorithms to reduce DWE. We assess the performance of the proposed algorithms by presenting objective measures for DWE in the original and the improved halftone videos. The expected contributions of this paper include three medium frame-rate binary video halftone enhancement algorithms that do the following: 1) reduce DWE under a spatial quality constraint; 2) reduce DWE under a spatial quality constraint with reduced complexity; and 3) reduce DWE under spatial and temporal quality constraints.

Robust Audio Watermarking Algorithm based on General Orthogonal Domain

In this paper, robust audio watermarking algorithm based on general orthogonal domain is proposed. By binary halftone pretreatment, one-dimensional meaningful audio watermarking is pretreated to high-fidelity binary audio. The host audio is raised to 2-dimensional space and divided into multi-sections. Each appropriate section is transformed by the general orthogonal transformation matrix. A bit binary audio watermarking signal is embedded, and the host audio is reduced to onedimensional space. So the host audio with watermarking is gotten. Because of the general orthogonal matrix, the security is higher. Experiments show that the algorithm has big embedding quantity, high security, strong practicability and robustness in enduring common attacks.

Audio Binary Halftone Watermarking Algorithm

Conventional audio watermarking method has the following deficiencies: the embedded watermarking signal bits are too less; the image watermarking pre-process is too simple which reduce the security; the embedded audio watermarking is meaningless binary sequence. To address these problems, we propose a robust audio watermarking algorithm based on audio binary halftone pre-process. The meaningful audio watermarking can be preprocessed to high-fidelity binary audio. The variable dimension operation is used to scramble the host audio. Experiments show the proposed algorithm has big embedding quantity, high security, strong practicability and robustness in enduring common attacks.

A Framework for the Assessment of Temporal Artifacts in Medium Frame-Rate Binary Video Halftones

Display of a video having a higher number of bits per pixel than that available on the display device requires quantization prior to display. Video halftoning performs this quantization so as to reduce visibility of certain artifacts. In many cases, visibility of one set of artifacts is decreased at the expense of increasing the visibility of another set. In this paper, we focus on two key temporal artifacts, flicker and dirty-window-effect, in binary video halftones. We quantify the visibility of these two artifacts when the video halftone is displayed at medium frame rates (15 to 30 frames per second). We propose new video halftoning methods to reduce visibility of these artifacts. The proposed contributions are (1) an enhanced measure of perceived flicker, (2) a new measure of perceived dirty-window-effect, (3) a new video halftoning method to reduce flicker, and (4) a new video halftoning method to reduce dirty-window-effect.

Optimal feedback quantizers for [formula omitted]-dimensional systems with discrete-valued input

This paper addresses an optimal design problem of feedback quantizers for a class of n -dimensional ( n -D) systems whose input signals are restricted to discrete-valued ones. First, for an arbitrary given quantizer, we analyze the maximum discrepancy between outputs of both the discrete-valued input n -D system connected with the quantizer and its corresponding continuous-valued input one. Based on this result, an optimal feedback quantizer which minimizes the discrepancy is derived in a closed form. A numerical example is given to demonstrate its effectiveness even in the case of coarse quantization. Second, we apply the optimal feedback quantizer to generate binary halftone images to verify its applicability and potential to real problems.

Reversible Data Hiding and Reversible Authentication Watermarking for Binary Images

Data hiding is a technique used to embed a sequence of bits in a host image with small visual deterioration and the means to extract it afterwards. Reversible data hiding allows, in addition, recovering the original cover-image exactly. Several reversible data hiding techniques have been developed but very few of them are appropriate for binary images. This paper proposes a reversible data hiding technique for binary images. This technique uses the Golomb code to compress prediction errors of low-visibility pixels, using its neighborhood as side information, to obtain the space to store the hidden data. The proposed technique is then used to reversibly authenticate binary images, including texts, drawings and halftones. All binary images we tested could be authenticated using the proposed technique, except unrealistically small or random images.

Simple multilevel halftoning excelled in gradation reproducibility

A simple multilevel halftoning method, which is based on the conventional error diffusion method and realizes halftoning excelled in the distribution of dots, is proposed. The proposed method consists of three steps, e.g., the image decomposition, the generation of binary halftone images by the error diffusion, and the synthesis of a multilevel halftone image, and each step does not require a complicated algorithm. The effectiveness of the proposed method is indicated by applying it to three- and four-level halftoning of gray-tone and natural images.

Optimal Dynamic Quantizers for 2D Systems with Discrete-Valued Input and Its Application to Generation of Binary Halftone Images

This paper addresses an optimal design problem of dynamic quantizers for a class of 2D systems with discrete-valued control input. First, we derive a closed form expression of the performance of a class of dynamic quantizers. Next, based on that, an optimal dynamic quantizer is provided. Finally, we apply the optimal dynamic quantizer to generate binary halftone images.

A Method for Classifying Halftone Patterns Based on Pattern Morphology

Different classification methods have been used to categorize the digital halftone algorithms and to help match the algorithms to the printer capabilities. The existing classification methods use the dot distribution, the dot generation process or a general description of the halftone pattern power spectra as basis for classification. Recent progress in understanding the interaction between the binary halftone patterns and the printer capabilities suggests that an optimal classification method may be based on the halftone pattern morphology. In this study, we review the existing classification methods, and introduce an alternative method based on the morphological similarities of binary halftone patterns. The method uses topological measurements of the halftone pattern to describe its morphology. The simplicity of the method permits its application to various areas of printing research such as printer characterization, toner deposition studies and development of printer models. As an example, we present a case study where we compared our proposed classification method with a commonly used method in their application to the development of a printer model. In this comparison our morphologically based classification method yielded improved printer predictions.

離散値入力型2Dシステムのための最適動的量子化器と2値ハーフトーン画像生成への応用

This paper addresses an optimal design problem of dynamic quantizers for a class of 2D systems with discrete-valued control input. First, we derive a closed form expression of the performance of a class of dynamic quantizers. Next, based on that, an optimal dynamic quantizer is provided. Finally, we apply the optimal dynamic quantizer to generate binary halftone images.

Colorant-based direct binary search halftoning

Abstract. In this paper, we propose color design criteria for uniformcolor textures, and present a new colorant-based color halftoningtechnique which meets these criteria, and hence generates highquality color halftones. The basic idea behind our halftoning methodis to control the quality of each colorant texture separately alongwith the total dot distribution. In order to achieve this, we first set thetotal dot arrangement and then color the dots optimally without al-tering the total dot arrangement. This corresponds to a constrainedoptimization problem, and we solve this via the swap-only directbinary search heuristic. We employ a luminance human visual sys-tem model to enforce exclusion of visually nonhomogeneous pat-terns for the total dot distribution, as well as for each individual colo-rant texture. Examples of color halftone images generated using ourtechnique are compared to images produced by a plane-independent color halftoning algorithm and by the HP 970 Cx inkjetprinter driver.

Optical proximity correction for intermediate-pitch features using sub-resolution scattering bars

Using our original scattering bar implementation as a starting point, we identify two major discontinuities in the CD versus pitch curve. The first discontinuity occurs at the pitch where two standard scattering bars will no longer fit between features at the proper optical distance and must be replaced by a single shared bar. The second discontinuity occurs at the pitch where a single shared bar no longer fits between features at the proper optical distance, and must be deleted. We propose several techniques that can be used in the pitch range around these discontinuities that allow us to decompose them into a finer series of smaller discontinuities, in effect smoothing out the curve. We introduce the concepts of “placement elasticity” and “optical weight modulation,” and two new classes of scattering bars: thin scattering bars and binary halftone scattering bars. We combine all of these elements in a hybrid optical proximity correction strategy, recommending actual dimensions for i-line, KrF (248 nm) and ArF (193 nm) reticles. We report both simulated and actual results for an i-line embodiment of this approach, demonstrating a greater than 50% improvement in overlapped depth-of-focus for both on-axis and off-axis illumination.