Half-Art——一种基于Halftone和QArt的新型二维码艺术化算法

为了提高二维码的辨识度和多样性,对Halftone算法的基本思想和优缺点进行了分析,并对其应用进行了扩展.结合Halftone和QArt的部分思想,提出了一种新型的艺术化算法——Half-Art.该算法分为数据修饰和图片处理两个阶段,分别使用了里德-所罗门码的数学特性和二值化后的图层蒙版粘贴算法将二维码向目标图片拟合.Half-Art算法综合了Halftone和QArt两种算法的优点,弥补了Halftone算法杂点过多、QArt算法拟合程度不高等缺点,优化后的二维码在通过电子渠道传播时具有良好的可读性.

Watermark Embedding for Direct Binary Searched Halftone Images by Adopting Visual Cryptography

In this paper,two methods are proposed to embed visual watermark into direct binary search(DBS)halftone images,which are called Adjusted Direct Binary Search(ADBS)and Dual Adjusted Direct Binary Search(DADBS).DADBS is an improved version of ADBS.By using the proposed methods,the visual watermark will be embedded into two halftone images separately,thus,the watermark can be revealed when these two halftone images are overlaid.Experimental results show that both methods can achieve excellent image visual quality and decoded visual patterns.

Microscopic Halftone Image Segmentation

Microscopic halftone image recognition and analysis can provide quantitative evidence for printing quality control and fault diagnosis of printing devices, while halftone image segmentation is one of the significant steps during the procedure. Automatic segmentation on microscopic dots by the aid of the Fuzzy C-Means (FCM) method that takes account of the fuzziness of halftone image and utilizes its color information adequately is realized. Then some examples show the technique effective and simple with better performance of noise immunity than some usual methods. In addition, the segmentation results obtained by the FCM in different color spaces are compared, which indicates that the method using the FCM in the f 1f 2f 3 color space is superior to the rest.

Thermodynamics-inspired inverse halftoning via multiple halftone images

Based on an analogy between thermodynamics and Bayesian inference,inverse halftoning was formulated using multiple halftone images based on Bayesian inference using the maximizer of the posterior marginal(MPM) estimate.Applying Monte Carlo simulation to a set of snapshots of the Q-Ising model,it was demonstrated that optimal performance is achieved around the Bayes-optimal condition within statistical uncertainty and that the performance of the Bayes-optimal solution is superior to that of the maximum-a-posteriori(MAP) estimation which is a deterministic limit of the MPM estimate.These properties were qualitatively confirmed by the mean-field theory using an infinite-range model established in statistical mechanics.Additionally,a practical and useful method was constructed using the statistical mechanical iterative method via the Bethe approximation.Numerical simulations for a 256-grayscale standard image show that Bethe approximation works as good as the MPM estimation if the parameters are set appropriately.

Novel attribute-based framework for halftone watermarking

A novel attribute-based framework is proposed to tackle the problem of halftone water- marking in combination of the spatial/transformation domain. The challenge is that the host image is continuous, while the watermarked halftone is bi-level. To search for a solution, an attribute image is defined as a good connection between the original grayscale image and its halftone image. When the attribute image is used as a watermark carrier, it helps to fred the watermarked halftone efficiently by solving a constrained modified direct binary search problem. Experimental results demonstrate that the proposed scheme in comparison with other similar methods maintains high watermark capacity with good image quality, high robustness, processing efficiency and easy decoding. Especially it has a good performance in printing application.

Secure separable reversible data hiding of halftone image in blockchain

To realize the distributed storage and management of a secret halftone image in blockchain,a secure separable reversible data hiding(RDH)of halftone image in blockchain(SSRDHB)was proposed.A secret halftone image can be used as the original image to generate multiple share images which can be distributed storage in each point of blockchain,and additional data can be hidden to achieve management of each share image.Firstly,the secret halftone image was encrypted through Zu Chongzhi(ZUC)algorithm by using the encryption key(EK).Secondly,the method of using odd or even of share data was proposed to hide data,and a share dataset can be generated by using polynomial operation.Thirdly,multiple share images can be obtained through selecting share data,and different additional data can be hidden through controlling odd or even of share data,and additional data can be protected by using data-hiding key(DK).After sharing process,if the receiver has both keys,the halftone image can be recovered and additional data can be revealed,and two processes are separable.Experiment results show that multiple share images hidden additional data can be obtained through SSRDHB,and the halftone image can be recovered with 100%by picking any part of share images,and one additional data can be revealed with 100%by picking any one share image.

A Secure Visual Cryptography Scheme Using Private Key with Invariant Share Sizes

Visual cryptography (VC) is one of the best techniques used to secure information. It uses the human vision to decrypt the encrypted images without any cryptographic computations. The basic concept of visual cryptography is splitting the secret image into shares such that when the shares are stacked, the secret image is revealed. In this paper we proposed a method that is based on the concept of visual cryptography for color images and without any pixel expansion which requires less space. The proposed method is used to encrypt halftone color images by generating two shares, random and key shares which are the same size as the secret color image. The two shares are generated based on a private key. At the receiving side, the secret color image is revealed by stacking the two shares and exploiting the human vision system. In this paper, we produce an enhanced form of the proposed method by modifying the encryption technique used to generate the random and the key shares. Experimental results have shown that the proposed and the enhanced methods suggest an efficient way to encrypt a secret color image with better level of security, less storage space, less time of computation and with a better value of PSNR.

基于进化计算的Halftoning算法

描述了进化计算在ｈａｌｆｔｏｎｉｎｇ算法中的应用，在保真显示或打印机上输出图像时，需要用ｈａｌｆｔｏｎｉｎｓ技术将多灰度图像转换为二值图像。一般来讲，保真满意的图像必定有高的立体和灰度级质量。在研究中，ｈａｌｆｔｏｎｉｎｇ算法被看作一个优化问题，即在ｈａｌｆｔｏｎｉｎｇ图像中搜索黑色像素的位置，以使图像具有较好的视觉效果。为解决这个问题，一个简单ＧＡ（ＳＧＡ）和一个单一群体的ＧＡ（ＳＰＧ）被用于ｈａｌｆｔｏｎｉｎｇ算法中。文中显示了一些由进化计算获得ｈａｌｆｔｏｎｉｎｇ图像，并演示它们的搜索效率。

CMAC Based Color Separation in Printing Images

To over come the drawbacks existing in current measurement methods for detecting and controlling colors in printing process, a new medal for color separation and dot recognition is proposed from a view of digital image processing and patter recognition. In this model, firstly data samples are collected from some color patches by the Fuzzy C-Means （FCM） method; then a classifier based on the Cerebellar Model Articulation Controller （CMAC） is constructed which is used to recognize color pattern of each pixel in a microscopic halftone image. The principle of color separation and the algorithm model are introduced and the experiments show the effectiveness of the CMAC-based classifier as opposed to the BP network.

Multi-Level Halftoning by IGS Quantization

Improved gray-scale (IGS) quantization is a known method for re-quantizing digital gray-scale images for data compression while producing halftones by adding a level of randomness to improve visual quality of the resultant images. In this paper, first, analyzing the IGS quantizing operations reveals the capability of conserving a DC signal level of a source image through the quantization. Then, a complete procedure for producing a multi-level halftone image by IGS quantization that can achieve the DC conservation is presented. Also, the procedure uses the scanning of source pixels in an order such that geometric patterns can be prevented from occurring in the resulting halftone image. Next, the performance of the multi-level IGS halftoning is evaluated by experiments conducted on 8-bit gray-scale test images in comparison with the halftoning by error diffusion. The experimental result demonstrates that a signal level to be quantized in the IGS halftoning varies more randomly than that in the error diffusion halftoning, but not entirely randomly. Also, visual quality of the resulting halftone images was measured by subjective evaluations of viewers. The result indicates that for 3 or more-bit, in other words, 8 or more-level halftones, the IGS halftoning achieves image quality comparable to that by the error diffusion.

A New Steganography Method Based on the Complex Pixels

Today steganography has attracted the attention of many researchers. In this paper, we propose a new steganography method for secure Data communication on half tone pictures. Using the halftone pictures improve the security and capacity. In this method, the complexity of every pixel in picture is computed, then a neibourhood is defined to compute the complexity of every pixel, and then the complexity of every pixel is computed in the neibourhood. Placing data in the monotonous areas of halftone can explain the presence of hidden data. A method has been represented that surveys the position of every pixel neibouring others and prevents including in monotonous areas. If that was a complicated one, steganography bit after stonehalf will be hidden after scrolling the whole, the process of spreading error will be done. Performing the suggested method improves the quality of placing picture and increases its security.

理解光与阴影的关系

在以前的讲座中，我们通过建模练习不仅练习了绘画能力，而且通过直接使用粘土及发泡树脂制作建模，学会了如何准确地把握物体形态，以及如何才能具备敏锐的观察力及感觉，在这一讲中，我们将朋CG建模引申开来，不仅要介绍纹理及灯光的处理方法，而且要将重点放在如何理解“光与阴影的调子”上，所谓“调子”，

多灰度级halftoning图像处理的新算法

提出ｈａｌｆｔｏｎｉｎｇ图像处理的一种新算法——匹配误差的扩散算法，它有效地消除了误差扩散算法的一些缺点．不仅如此，匹配误差的扩散算法也被用于多灰度级的ｈａｌｆｔｏｎｉｎｇ图像，结果表明有较好的视觉效果．

HP DesignJet 755CM:海报打印要点

11995美元的HP DesignJet 755CM是大幅面喷墨打印机。它向大型打印更便宜的方向又前进了一大步,但并不是大多数台式机用户每天进行打印工作时的选择。 毋庸置疑,这种打印机不是用于桌面的——任何人的桌面。Design-Jet的重量为135磅,与一个锯床占地大小相同,它的大小和重量与一台PC印刷机一样。幸运的是,这种打印机的底下有可锁定的轮子。

An improved parallel contrast-aware halftoning

Digital image halftoning is a widely used technique. However, achieving high fidelity tone reproduction and structural preservation with low computational time cost remains a challenging problem. This paper presents a highly parallel algorithm to boost real-time application of serial structure-preserving error diffusion. The contrast-aware halftoning approach is one such technique with superior structure preservation, but it offers only a limited opportunity for graphics processing unit(GPU) acceleration. Our method integrates contrast-aware halftoning into a new parallelizable error-diffusion halftoning framework. To eliminate visually disturbing artifacts resulting from parallelization, we propose a novel multiple quantization model and space-filling curve to maintain tone consistency, blue-noise property, and structure consistency. Our GPU implementation on a commodity personal computer achieves a real-time performance for a moderately sized image. We demonstrate the high quality and performance of the proposed approach with a variety of examples, and provide comparisons with state-of-the-art methods.

A robust method for inverse halftoning via two-dimensional nonlinear pyramid

Based on the principle of spatial pyramid for signal, a multi-scale transform of two-dimensional （2D） interpolating pyramid is constructed by the nonlinear median operator. The transform properties of error diffuse halftoning noise on multiple scales are investigated and analyzed through experiments. According to these properties, a robust inverse halftoning method is proposed. The halftoning image is firstly preprocessed by a Gaussian low-pass filter, and decomposed by the one-scale transform. Then a Wiener filter is employed to the detailed coefficients. Finally an inverse image is reconstructed. Experimental results show that the proposed transform has the advantage of separating the halftoning noise and image detail over linear multi-resolution transform. The presented inverse halftoning method performs some excellent abilities on sharp edge, high peak signal-to-noise ratio （PSNR）, and small memory requirement.