Restoration of error-diffused images using POCS

A class of inverse halftoning methods together with post-processing is proposed in this paper. In order to optimize the inverse operation of halftoning, we adopt the inverse modeling concept to find the least-squares solution of this problem. And then, the knowledge of image characteristics helps us in designing improved algorithms that produce the most promising pictures to our eyes. They are conceptually rather different from the traditional inverse halftoning methods that use simple low-pass filters. Furthermore, we develop a general space-varying sliding-window filter (SV-SWF) scheme. The goal is to be able to handle various types of pictures using the same basic inverse halftoning structure together with spatially adaptive parameters. This universal inverse halftoning operator is achieved by using an adequate classification scheme to separate image data into different groups, each corresponding to a set of pre-trained parameters. Due to the additional information in the inputs and the outputs utilized in our processing, better reconstructed images are obtained. >

Network-on-Chip (NoC) links consume a significant fraction of the total NoC power. We present Selective Packet Interleaving (SPI), a flit transmission scheme that reduces power consumption in NoC links. SPI decreases the number of bit transitions in the links by exploiting the multiplicity of virtual channels in a NoC router. SPI multiplexes flits to the router's output link so as to minimize the number of bit transitions from the previously transmitted flit. Analysis and simulations demonstrate a reduction of up to 55% in the number of bit transitions and up to 40% savings in power consumed on the link. SPI benefits grow with the number of virtual channels. SPI works better for links with a small number of bits in parallel. While SPI compares favorably against bus inversion, combining both schemes helps to further reduce bit transitions.

Image data hiding is the hiding of invisible patterns in an image without degrading its visual quality. The hidden pattern can be visualized by overlaying the original image with watermarked ones or by applying an extraction algorithm. If the hidden pattern is visualized using the overlaying method, it can also be visualized using a simple XNOR operation. In the case that hidden data is extracted by a specific algorithm, it is commonly called steganography. In this paper we propose a method called dot diffusion with nonlinear thresholding (DDNT) to embed hidden data in halftone images, where the hidden data can be extracted by overlaying original and watermarked images or by performing the XNOR process on these two images. The main advantage of this method is that the hidden pattern's intensity can be adjusted by three parameters. The DDNT data hiding method utilizes the inherent parallelism in dot diffusion halftoning method, although it suffers from its lower visual quality than some other halftoning methods such as error diffusion

Inverse halftoning is a process to recover the multi-tone images from halftone images. Since halftoning is not an invertible process, there is no clear best or unique approach for inverse halftoning. In this paper, we propose a low complexity, high quality Fast Adaptive-spatial-varying Filtering (FAF) for inverse halftoning, which is robust to different kinds of halftone images. FAF is a two-step algorithm combining spatial-variant and spatial invariant filtering. Firstly, it uses spatial invariant filter to suppress the halftone noise and then generates the target image. Secondly, it uses spatial variant filter to filter the halftone image based on the target image. Combining these two filtering, FAF can filter the noise and preserve edges of the halftone image at the same time, which is essential for effective inverse halftoning.

Color halftoning is a method for representing continuous tone color images with limited colors. To implement halftone, error diffusion is one of the most popular algorithms due to its highperformance results. In the conventional error diffusion, the fixed thresholds and filter weights are used. In the process, many artifacts are introduced in the halftone images as side effects. With the color aspect, each of the three color planes is independently calculated during the process of traditional error diffusion. However, the pattern of dots formed independently by combining the dots of each of color planes is often not visually pleasing because no effort is made to insure that the dots of each of the different color planes are ideally distributed relative to the dots of the other color planes. In this paper, we present an integrated error diffusion algorithm in which variable filter weights, threshold matrix, serpentine scan path and multi-color halftoning are used to reduce the noises generated during the halftone process. Our experimental results showed that worm-like artifacts, structural artifacts and start-up artifacts are successfully decreased and the color halftoned images are more comfortable to the human visual system.

Inverse color to black-and-white halftone conversion via dictionary learning and color mapping

Exhaustive self-testing of combinational circuitry within the framework of the level-sensitive scan design (LSSD) discipline requires that every output node depend on a small number of input nodes. We present here efficient algorithms that take an arbitrary block of combinational logic and add to it the smallest number of bits of new LSSD registers necessary to: (1) partition the logic so that no output depends on more thank inputs, and (2) maintain timing within the block (so that all input-to-output paths encounter the same number of bits of register). Our partitioning algorithms conform to two different design constraints. We also show that the unconstrained partitioning problem is NP-complete.

In this paper, a low computational complexity method is proposed to embed a multi-tone visual pattern using the concept of secret sharing. One halftone image is obtained using regular error diffusion, and the other image is obtained using the proposed Generalized Noise-Balanced Error Diffusion (GNBEDF) in considering the properties of the watermark and the first halftone image in the same time. With the proposed method, the bi-level watermark embedding becomes a special case to this technology. The bi-level watermark decoding can be simply achieved via printing the two halftone images onto two transparencies and then superimposing them together to reveal the watermark pattern. However, as the multi-tone watermark is involved, the proposed Gaussian Difference (GD) approach is needed to perform the decoding to produce a decoded multi-tone watermark. Throughout this work, a lowpass filter obtained by Least-Mean-Square is employed to assess the image quality.

Various methods have been proposed for inverse halftoning (IH) of error diffusion (ED) images. Among them look-up table (LUT) method based on every possible combination of the bi-level output of reference pixels has been considered to be most effective and quite practical since IH function can be generated by simple averaging of the histogram of original con-tone levels of the target pixels in each context, and the image quality can be controlled by the number of reference pixels. In this paper, we propose a hybrid system, in which each context is composed of the combination of the conventional logic of some part of reference pixels and reduced state information given by the number of black pixels in other reference pixels. The result shows that the PSNR compared under the same number of contexts are improved from the conventional method especially when applied to the images not included in the training data

A halftone watermarking method of high quality, robustness, and capacity flexibility is presented in this paper. An objective halftone image quality evaluation method based on the human visual system obtained by least-mean-square is also introduced. In the encoder, the kernels-alternated error diffusion (KAEDF) is applied. This is able to maintain the computational complexity at the same level as ordinary error diffusion. Compared with Hel-Or (2001) using ordered dithering, the proposed KAEDF yields a better image quality through using error diffusion. We also propose a weighted lookup table (WLUT) in the decoder instead of LUT, as proposed by Pei and Guo (2003), so as to achieve a higher decoded rate. As the experimental results demonstrated, this technique is able to guard against degradation due to tampering, cropping, rotation, as well as print-and-scan processes in error-diffused halftone images.

Based on digitized TV frames a computer simulation study was conducted on a motion -adaptive TV data compression scheme, defined as one in which a 2- dimensional transformapplied to subblocks is followed by the transmission to the receiving site of only changedsubblocks. Performance was measured both by calculation of Normalized Mean Square Errorand by subjective viewing of reconstructed frames. Two systems designs leading to 512x512resolution operation (one based on the Hadamard and one on the Discrete Cosine Transform)were prepared.IntroductionThe motion -adaptive TV data compression described herein is more effective than conven-tional intraframe techniques because it encompasses them and furthermore takes advantageof the correlation between frames by updating only those subblocks which have changed.Following a 2 -D transform performed on small (e.g. 8x8) subblocks, intraframe compressionis achieved by assigning a small number of bits (or none) to each transform coefficient.This bit allocation is made adaptive by assigning fewer bits to those subblocks within aframe which exhibit less busyness or activity. Next, motion -adaptivity, a form of inter -frame compression, is provided by having the amount of change in coefficients between thecurrent subblock and the corresponding subblock of the previous frame determine which trans-form subblocks to transmit. This process has been simulated and an approach to hardwareimplementation derived.BackgroundTwo -dimensional transforms combined with frame to frame motion -adaptivity achieve highcompression ratios because they exploit pixel correlation in all three dimensions.

A steganographic technique inspired by rook is presented in this paper to ensure privacy and secrecy. In this approach, the cover image is partitioned into n × 1 pixel blocks and converted equivalent n × 8 binary bit planes. Then the functional output of each block is calculated on the basis of the number of rook positions, which are attacked by opponent rooks. The rook is a chess piece that moves only forward and backward in a straight line. In binary bit plane, 0 and 1 are considered as a black and white opponent rook, respectively. The secret information is considered as stream of binary bits. The binary bits of secret information are compared with the functional output of the corresponding block. If it is equal to the functional output of the corresponding block, then nothing needs to be done. In case of inequality, the small number of bits needs to be flipped in such a way that the functional output of the corresponding block becomes equal to the corresponding secret binary bits and the distortion of the cover is minimized.

The defining characteristic of a networked control system (NCS) is having a feedback loop that passes through a local area computer network. This paper considers nonlinear systems controlled in this manner, and demonstrates that for sufficiently high transmission rates, the network may be considered transparent. Three methods of scheduling data packets are compared: a static scheduler (token ring), the try-once-discard (maximum-error-first) scheduler with continuous priority levels, and the try-once-discard scheduler with discrete priority levels. The third method is of particular interest when only a small number of bits are available for collision resolution. Asymptotic stability is guaranteed in the first two cases, and ultimate uniform boundedness in the third. In the final section, simulations demonstrate the theoretical results. The contributions of this paper are two-fold: first, it extends the earlier results on NCS to nonlinear systems, and second, it allows for finite word-length message identifiers.

This paper introduces a best approach for Least Significant Bit (LSB) based on image steganography that enhances the existing LSB substitution techniques to improve the security level of hidden information. It is a new approach to substitute LSB of RGB true color image. The new security conception hides secret information within the LSB of image where a secret key encrypts the hidden information to protect it from unauthorized users. In general, in LSB methods, hidden information is stored into a specific position of LSB of image. For this reason, knowing the retrieval methods, anyone can extract the hidden information. In our paper, hidden information is stored into different position of LSB of image depending on the secret key. As a result, it is difficult to extract the hidden information knowing the retrieval methods. We have used the Peak Signal-to-Noise Ratio (PSNR) to measure the quality of the stego images. The value of PSNR gives better result because our proposed method changes very small number of bits of the image. The obtained results show that the proposed method results in LSB based image steganography using secret key which provides good security issue and PSNR value than general LSB based image steganography methods.

This paper presents an efficient method to block unknowns for temporal compactors. The proposed blocking logic can reduce data volume required to control the blocking logic and increase the number of scan cells that are observed by temporal compactors. Control patterns, which specify values required at the control signals of the blocking logic, are compressed by linear feedback shift register reseeding. In this paper, the blocking logic gates for some scan chains that do not capture unknowns are bypassed. Since all scan cells in these scan chains can be observed without specifying the corresponding bits in control patterns, more scan cells are observed while a smaller number of bits are required to be specified. The seed size is further reduced by reducing the numbers of specified bits in the densely specified control patterns. The proposed method can always achieve the same fault coverage that can be achieved by directly observing scan chains without any output compaction. Experiments with large industrial designs clearly demonstrate that the proposed method is scalable to large circuits. Hardware overhead for the proposed unknown blocking scheme is very low.