Direct Binary Search Research Articles

Advanced DBS (Direct-Binary Search) Method for Compensating Spatial Chromatic Errors on RGB Digital Holograms in a Wide-Depth Range with Binary Holograms

Advanced DBS (Direct-Binary Search) Method for Compensating Spatial Chromatic Errors on RGB Digital Holograms in a Wide-Depth Range with Binary Holograms

Halftoning of images in visual cryptography by direct bin ary search

Halftoning of images in visual cryptography by direct bin ary search

Data Hiding by White Modulation in Color Direct Binary Search Halftones

Data Hiding by White Modulation in Color Direct Binary Search Halftones

High-quality blind watermarking in halftones using random toggle approach

This paper presents a blind watermarking method for embedding large data into halftone images. Watermarking in ready-to-print halftones is desirable in printer applications such as authentication and document/image security. It is challenging to embed large information into halftones, while maintaining high image quality. In this paper, we first review a series of halftone watermarking methods that embed data by using Embedding Toggle (ET) in the selected positions. We find that such ET-based methods have two shortcomings: 1) the image quality is limited because of the unknown input data and randomly selected embedding positions, and 2) the selected embedding positions must be recorded to retrieve the hidden data. To tackle the above disadvantages, this study makes two improvements. First, we propose a random toggle approach, in which the embedding positions are movable. Therefore, after the data are embedded, each dot can still be shifted to the most appropriate position to improve the image quality. Second, a self-decodable even/odd parity checking scheme is proposed to embed one bit information in each image block. We also propose a new search strategy, called Swap-Only Block-Based (SOBB) search. By integrating SOBB search with the direct binary search method, the image quality can be greatly improved without damaging the hidden data. From experimental results, the proposed method demonstrated sufficient robustness and excellent image quality.

Color halftoning based on Neugebauer Primary Area Coverage

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.

Generation of binary holograms for deep scenes captured with a camera and a depth sensor

This work presents binary hologram generation from images of a real object acquired from a Kinect sensor. Since hologram calculation from a point-cloud or polygon model presents a heavy computational burden, we adopted a depth-layer approach to generate the holograms. This method enables us to obtain holographic data of large scenes quickly. Our investigations focus on the performance of different methods, iterative and noniterative, to convert complex holograms into binary format. Comparisons were performed to examine the reconstruction of the binary holograms at different depths. We also propose to modify the direct binary search algorithm to take into account several reference image planes. Then, deep scenes featuring multiple planes of interest can be reconstructed with better efficiency.

Orientation Modulation for Data Hiding in Chrominance Channels of Direct Binary Search Halftone Prints

Orientation Modulation for Data Hiding in Chrominance Channels of Direct Binary Search Halftone Prints

Orientation Modulation for Data Hiding in Chrominance Channels of Direct Binary Search Halftone Prints

Orientation Modulation for Data Hiding in Chrominance Channels of Direct Binary Search Halftone Prints

Control of broadband optically generated ultrasound pulses using binary amplitude holograms.

In this work, the use of binary amplitude holography is investigated as a mechanism to focus broadband acoustic pulses generated by high peak-power pulsed lasers. Two algorithms are described for the calculation of the binary holograms; one using ray-tracing, and one using an optimization based on direct binary search. It is shown using numerical simulations that when a binary amplitude hologram is excited by a train of laser pulses at its design frequency, the acoustic field can be focused at a pre-determined distribution of points, including single and multiple focal points, and line and square foci. The numerical results are validated by acoustic field measurements from binary amplitude holograms, excited by a high peak-power laser.

Quad-interleaved Block Level Parallel Direct Binary Search Algorithm

Direct Binary Search (DBS), as one of the three categories of halftoning, provides the best, visually pleasing halftoning quality. However, as a sequential algorithm, DBS is most computational complex so it always plays the role of offline algorithm for other halftoning categories (like tone dependent error diffusion, hybrid screen, etc.). Meanwhile, it is seldom directly works as a real-time/online solution for current commercial printers. In this paper, we would like to present a parallel version DBS with same image quality compared with original DBS, which can fit the current Same Instruction Multiple Data (SIMD) system, like General-Purpose Graphics Processing Unit (GP-GPU), and furthermore, there will be the potential that DBS can work on current multi-core system as real-time solution for halftoning.

Theoretical Bounds of Direct Binary Search Halftoning.

Direct binary search (DBS) produces the images of the best quality among half-toning algorithms. The reason is that it minimizes the total squared perceived error instead of using heuristic approaches. The search for the optimal solution involves two operations: (1) toggle and (2) swap. Both operations try to find the binary states for each pixel to minimize the total squared perceived error. This error energy minimization leads to a conjecture that the absolute value of the filtered error after DBS converges is bounded by half of the peak value of the autocorrelation filter. However, a proof of the bound's existence has not yet been found. In this paper, we present a proof that shows the bound existed as conjectured under the condition that at least one swap occurs after toggle converges. The theoretical analysis also indicates that a swap with a pixel further away from the center of the autocorrelation filter results in a tighter bound. Therefore, we propose a new DBS algorithm which considers toggle and swap separately, and the swap operations are considered in the order from the edge to the center of the filter. Experimental results show that the new algorithm is more efficient than the previous algorithm and can produce half-toned images of the same quality as the previous algorithm.

Converting optical scanning holograms of real objects to binary Fourier holograms using an iterative direct binary search algorithm.

In this paper, we present a three-dimensional holographic imaging system. The proposed approach records a complex hologram of a real object using optical scanning holography, converts the complex form to binary data, and then reconstructs the recorded hologram using a spatial light modulator (SLM). The conversion from the recorded hologram to a binary hologram is achieved using a direct binary search algorithm. We present experimental results that verify the efficacy of our approach. To the best of our knowledge, this is the first time that a hologram of a real object has been reconstructed using a binary SLM.

Progressive halftone watermarking using multilayer table lookup strategy.

In this paper, a halftoning-based multilayer watermarking of low computational complexity is proposed. An additional data-hiding technique is also employed to embed multiple watermarks into the watermark to be embedded to improve the security and embedding capacity. At the encoder, the efficient direct binary search method is employed to generate 256 reference tables to ensure the output is in halftone format. Subsequently, watermarks are embedded by a set of optimized compressed tables with various textural angles for table lookup. At the decoder, the least mean square metric is considered to increase the differences among those generated phenotypes of the embedding angles and reduce the required number of dimensions for each angle. Finally, the naïve Bayes classifier is employed to collect the possibilities of multilayer information for classifying the associated angles to extract the embedded watermarks. These decoded watermarks can be further overlapped for retrieving the additional hidden-layer watermarks. Experimental results show that the proposed method requires only 8.4 ms for embedding a watermark into an image of size 512×512 , under the 32-bit Windows 7 platform running on 4GB RAM, Intel core i7 Sandy Bridge with 4GB RAM and IDE Visual Studio 2010. Finally, only 2 MB is required to store the proposed compressed reference table.

Optical alignment of pixelated 4f optical system using multiplexed filter

Novel optical alignment techniques to perform precise alignment of a typical pixelated 4f optical system are presented in this paper. These techniques use optical multiplexed matched filters, which were designed using a simple, efficient iterative optimization algorithm, known as direct binary search. Three alignment challenges are identified: positioning, focusing, and magnification. The first two alignments were performed using the optical multiplexed matched filtering technique, and the last one was performed using a new optical arrangement. Experimental results of the new alignment techniques and a simple optical pattern recognition problem to demonstrate the benefits of the new alignment techniques are also presented. Two pixelated, electrically addressed spatial light modulators (128 × 128 pixels and one pixel width is 80 μm) were used to represent the input and filter planes. The results clearly show that the new alignment techniques allow the 4f system to be aligned to a precision of 80 μm in the x-y direction and 0.716 mm in the z direction.

A Method of Digital Halftoning through Approximated Optimization of Scale-Related

We gain the scale-related characterization of the original image using the discrete wavelet transform. The boundary information of the image target is fused by the wavelet coefficients of the correlation between wavelet transform layer, which to increase the pixel resolution scale. We apply the inter-scale fusion method to gain fusion coefficient of the fine-scale, which take into account the detail of the image and approximate information, which the fusion coefficient are referred to as the weighting operator and to establish the boundary energy function. In the halftone process, each clustering uses the weighted least-squares method through energy minimization via Direct Binary Search algorithm, which to gain halftoning image. Simulation results on typical test images further confirm the performance of the new approach.

Efficient Halftoning Based on Multiple Look-Up Tables

Look-up table (LUT) halftoning is an efficient way to construct halftone images and approximately simulate the dot distribution of the learned halftone image set. In this paper, a general mechanism named multiple look-up table (MLUT) halftoning is proposed to generate the halftones of direct binary search (DBS), whereas the high efficient characteristic of the LUT is still preserved. In the MLUT, the standard deviation is adopted as an important feature to classify various tables. In addition, the proposed quick standard deviation evaluation is employed to yield an extremely low computational complexity in calculating the standard deviation. In the parameter optimization, the autocorrelation is adopted because it can fully characterize the periodicity of dot distribution. Experimental results demonstrate that the dot distribution generated by the proposed method approximates to that of the DBS, which enables the proposed scheme as a very competitive candidate in the copying and printing industry.

Direct Binary Search Based Algorithms for Image Hiding

Digital halftoning is an important process to convert a continuous-tone image into a binary image with pure black and white pixels. The Direct Binary Search (DBS) is one of the well-known halftoning methods that can generate high quality binary images. The main contribution of this paper is to present a DBS based halftoning method that conceals a binary image into two binary images. More specifically, three distinct gray scale images are given, such that one of them should be hidden in the other two gray scale images. Our DBS based halftoning method generates three binary images that reproduce the tone of the corresponding original three gray scale images. Quite surprisingly, the secret binary image can be seen by overlapping the other two binary images. In other words, the secret binary image is hidden in two public binary images. Also, it is very hard to guess the secret images using only one of the two public images, and both of these two public images are necessary to get the secret image. Another contribution of this paper is to extend our DBS based halftoning method to hide one image and more than one image into more than two images. The resulting images show that our DBS based halftoning method hides and recovers the original images. Hence, our DBS based halftoning technique can be used for watermarking as well as amusement purpose.

Clustered-Dot Halftoning With Direct Binary Search

In this paper, we present a new algorithm for aperiodic clustered-dot halftoning based on direct binary search (DBS). The DBS optimization framework has been modified for designing clustered-dot texture, by using filters with different sizes in the initialization and update steps of the algorithm. Following an intuitive explanation of how the clustered-dot texture results from this modified framework, we derive a closed-form cost metric which, when minimized, equivalently generates stochastic clustered-dot texture. An analysis of the cost metric and its influence on the texture quality is presented, which is followed by a modification to the cost metric to reduce computational cost and to make it more suitable for screen design.

Oriented Modulation for Watermarking in Direct Binary Search Halftone Images

In this paper, a halftoning-based watermarking method is presented. This method enables high pixel-depth watermark embedding, while maintaining high image quality. This technique is capable of embedding watermarks with pixel depths up to 3 bits without causing prominent degradation to the image quality. To achieve high image quality, the parallel oriented high-efficient direct binary search (DBS) halftoning is selected to be integrated with the proposed orientation modulation (OM) method. The OM method utilizes different halftone texture orientations to carry different watermark data. In the decoder, the least-mean-square-trained filters are applied for feature extraction from watermarked images in the frequency domain, and the naïve Bayes classifier is used to analyze the extracted features and ultimately to decode the watermark data. Experimental results show that the DBS-based OM encoding method maintains a high degree of image quality and realizes the processing efficiency and robustness to be adapted in printing applications.

Optical correlator-neural networks hybrid system for automatic angle measurement of two-dimensional objects

A new interpolation algorithm is proposed and demonstrated to perform automatic angle measurement of two-dimensional (2D) objects. The proposed algorithm works in conjunction with optical correlator neural network hybrid architecture (OCNN). The OCNN is trained with a combined algorithm of direct binary search and error back propagation. Input of the OCNN is presented with an image whose angle of rotation is to be measured, and output from the OCNN is fed into the proposed interpolation algorithm, which finally produces the rotation angle of the input image. Results of both computer simulation and experimental set-up are presented for an English alphabetic character as a 2D object. The experimental set-up consists of a real optical correlator using two spatial light modulators for both input and frequency plane representations and a PC based model of a single layer neural network. We obtained very low experimental mean absolute error of 3.18 deg with standard deviation of 2.9 deg.