A novel high payload steganography scheme based on absolute moment block truncation coding

In this paper, we propose an efficient steganography method in the compressed codes of absolute moment block truncation coding (AMBTC). Many recent related schemes focus on implementing reversible data hiding in compressed AMBTC bit stream. However, the reconstructed image of AMBTC is already lossy and the strict reversibility severely limits embedding capacity. Due to the simplicity and regularity of AMBTC codes, implementing irreversible hiding scheme causes very slight loss visual distortion of reconstructed image in exchange of significant improve in embedding capacity. In proposed scheme, smoothness of AMBTC compressed trio is firstly detected, which is then indicated by substituting the LSB of high quantity level with flag bit. For smooth trios, the differences between both quantity levels are firstly encoded by Huffman coding and then concatenated with secret data to generate modified low quantity levels. Meanwhile, all bits in bit planes of smooth trios are substituted with secret data as well. For complex trio, secret bits are only embedded into quantity levels, which is similar to smooth trio except for the differences are encoded by Lloyd-Max quantization. Experimental results indicate that proposed scheme outperforms prior methods both in imperceptivity and embedding capacity, which confirms the effectiveness and superiority of our work.

     

基于矢量量化的高效BTC图像编码算法

作为一种有损图像编码技术,块截短编码算法（BTC）的计算量较少,速度快,有较好的信道容错力,重建图像质量较高。然而,标准BTC算法的主要缺点是其压缩比特率比其他基于块图像编码的算法（如变换编码和矢量量化）高。为了降低比特率,提出了几种有效的BTC算法,还提出了一种简单的查表算法对每块的BTC量化数据编码,另外还引入了矢量量化技术以减少对位平面编码的比特数。为了减少由改进算法引入的额外失真,在每种提出的算法中,采用最优阈值而不用平均值作为量化阈值。     

An oblivious fragile watermarking scheme for images utilizing edge transitions in BTC bitmaps

As one of the famous block-based image coding schemes,block truncation coding(BTC) has been also applied in digital watermarking.Previous BTC-based watermarking or hiding schemes usually embed secret data by modifying the BTC encoding stage or BTC-compressed data,obtaining the watermarked image with poorer quality than the BTC-compressed version.This paper presents a new oblivious image watermarking scheme by exploiting BTC bitmaps.Unlike the traditional schemes,our approach does not really perform the BTC compression on images during the embedding process but utilizes the parity of the number of horizontal edge transitions in each BTC bitmap to guide the watermark embedding and extraction processes.The embedding process starts by partitioning the original cover image into non-overlapping 4×4 blocks and performing BTC on each block to obtain its BTC bitmap.One watermark bit is embedded in each block by modifying at most three pixel values in the block to make sure that the parity of the number of horizontal edge transitions in the bitmap of the modified block is equal to the embedded watermark bit.In the extraction stage,the suspicious image is first partitioned into non-overlapping 4×4 blocks and BTC is performed on each block to obtain its bitmap.Then,by checking the parity of the number of horizontal edge transitions in the bitmap,we can extract one watermark bit in each block.Experimental results demonstrate that the proposed watermarking scheme is fragile to various image processing operations while keeping the transparency very well.     

Lossless data hiding for absolute moment block truncation coding using histogram modification

This paper presents a lossless data hiding method for an absolute moment block truncation coding (AMBTC) images, which is a compressed grayscale image. It is not easy to hide secret data in an AMBTC-compressed image because it is composed of bit planes. Thus, it is very sensitive to change some pixels. Nevertheless, to improve the hiding capacity, we present an efficient extension of the histogram modification technique by counting the coefficients of the bit planes in each 4 × 4 block. In addition, our proposed scheme has low complexity and achieves a high embedding capacity with the good perceptual quality compared to the prior arts. In an experiment, we verified our proposed data hiding scheme through the comparison with previous methods.     

Secret sharing: using meaningful image shadows based on Gray code

Steganography, such as secret sharing, is an important technique to use for protecting transmitted confidential data from the attention of any adversaries. Gray code is a commonly encountered binary labeling that was proposed by Frank Gray of Bell Laboratories in 1940 to prevent errors when using pulse-code modulation to transmit signals. The main features of Gray code are its recursive construction method and the fact that any two adjacent codes change only one bit. According to our observations, the image pixel correction based on these features is suitable for application secret sharing without making significant changes to the pixel value. We designed a reversible secret sharing method using meaningful image shadows based on Gray code. Our design applies absolute moment block truncation coding (AMBTC) compression to reduce the transmission bit rate. The experimental results show that our scheme can achieve the adequate visual quality of shadow images with lower communication overhead, thus proving it practical for numerous applications.     

An FPGA implementation of a neural optimization of block truncation coding for image/video compression

This paper presents a Field Programmable Gate Array (FPGA) implementation for image/video compression using an improved block truncation coding (BTC) image compression technique. The improvement is achieved by employing a Hopfield neural network (HNN) to calculate a cost function upon which a block is classified as either a high- or a low-detail block. Accordingly, different blocks are coded with different bit rates and thus resulting in better compression ratios. The paper formulates the utilization of HNN within the BTC algorithm in such a way that a viable FPGA implementation is produced. The implementation exploits the inherent parallelism of the BTC/HNN algorithm to provide efficient algorithm-to-architecture mapping. The Xilinx VirtexE BTC implementation has shown to provide a processing speed of about 1.113 × 10⁶ of pixels per second with a compression ratio which varies between 1.25 and 2 bits/pixel, according to the image nature.     

Bit plane modification for improving MSE-near optimal DPCM-based block truncation coding

A hybrid method of block truncation coding (BTC) and differential pulse code modulation (DPCM) offers better visual quality than the standard BTC for small block sizes due to its inherent multitone representation. Recently, a two-level quantizer design method has been proposed to increase the coding performance of the DPCM-BTC framework. However, the design method is near optimal in the sense that its coding performance depends on the initial bit plane patterns. In this paper, we propose a bit plane modification (BPM) algorithm to achieve further performance improvement. The BPM algorithm, inspired by error diffusion, effectively distributes large quantization error at a certain pixel to its neighboring pixels having small quantization errors by changing partial bit patterns. Experimental results show that the proposed algorithm successfully achieves much higher coding performance than various conventional BTC methods. The average PSNR performance of the proposed method is 2.31 dB, 5.15 dB, and 5.15 dB higher than that of BTC, DPCM-BTC, and a recently developed BTC scheme using error diffusion and bilateral filtering, respectively.     

Enhanced interpolation-based AMBTC image compression using Weber’s law

Multimedia Tools and Applications - In this paper, we propose a new enhanced absolute moment block truncation coding (AMBTC) image compression method based on interpolation. The proposed...     

Pixel-based fragile image watermarking based on absolute moment block truncation coding

Multimedia Tools and Applications - A pixel-based fragile image watermarking method based on s absolute moment block truncation coding (AMBTC) is proposed in this paper. To enhance the readability...     

An efficient authentication method for AMBTC compressed images using adaptive pixel pair matching

The existing image authentication methods for absolute moment block truncation coding (AMBTC) modify the bits of quantitation levels or bitmaps to embed the authentication code (AC). However, the modification of the bits in these methods is equivalent to the LSB replacement, which may introduce undesirable distortions. Besides, the modification of bitmap for embedding AC reduces the image quality significantly, especially at image edges. Moreover, the existing methods might not be able to detect some special modifications to the marked image. In this paper, we propose an efficient authentication method for the AMBTC compressed image. AC is obtained from the bitmap and the location information, and is embedded into the quantization levels using the adaptive pixel pair matching (APPM) technique. Since the bitmap is unchanged and the APPM embedment is efficient, a high image quality can be achieved. The experimental results reveal that the proposed method not only significantly reduces the distortion caused by embedding but also provides a better authentication result when compared to the prior state-of-art works.

     

A high quality and small shadow size visual secret sharing scheme based on hybrid strategy for grayscale images

Many secret sharing schemes for digital images have been developed in recent decades. Traditional schemes typically must deal with the problem of computational complexity, and other visual secret sharing schemes come with a higher transmission cost and storage cost; that is, each shadow size is m times as big as the original secret image. The new (2,n) secret sharing scheme for grayscale images proposed in this paper is based a combination of acceptable image quality using block truncation coding (BTC), high compression ratio discrete wavelet transform (DWT) and good subjective performance of the vector quantization (VQ) technique. Experimental results confirm that our proposed scheme not only generates a high quality reconstructed original image but also generates small, random-like grayscale shadows.     

An Adaptive Two-Stage Edge Detection Scheme for Digital Color Images

An adaptive two-stage edge detection scheme for digital color images is proposed in this paper. In the first stage of this scheme, each three-dimensional color image is reduced to a one-dimensional gray-level image using the moment-preserving thresholding technique. Then, a new edge detection technique based on the block truncation coding scheme is introduced to detect the edge boundary in the second stage. The edge detection process makes use of the bit plane information of each BTC-encoded block to detect the edge boundary. The experimental results show that the performance of the detected edge image of the proposed scheme is as good as in Yang's scheme and in the Sobel operator. However, the computational cost consumed by the proposed scheme is less than that of Yang's scheme. In addition, the proposed scheme provides an adaptive edge quality decision mechanism. This mechanism can provide different edge images to meet various applications and the subjective evaluation. Moreover, this scheme locates the edge boundaries to the sub-pixel accuracy, which is an advantage to applications such as data hiding and image watermarking.     

Lossless visible watermarking based on adaptive circular shift operation for BTC-compressed images

Most existing BTC (Block Truncation Coding) based watermarking algorithms do not fully exploit visual perception of the host images. These schemes cannot obtain visual quality of stego-images and recover original images without distortion. To solve this issue, a new reversible visible watermarking scheme based on AMBTC (Absolute Moment Block Truncation Coding) domain is proposed. First, the proposed scheme uses adaptive pixel circular shift operation that adapts to local properties of the image to embed the visible watermark into two level (one-bit) nonparametric quantization levels of AMBTC according to the parity of the bit plane of AMBTC triple. The watermark signal can be extracted according to the parity of the Bit plane. The experimental results prove that the algorithm can achieve high visual quality of stego-images and recover original BTC-compressed image losslessly. Moreover, it is robust against common signal processing attacks. The visible watermarking algorithm can be applied to copyright of digital images in real-time environment because of the low time consumption due to the simplicity of AMBTC.     

Tamper detection and image recovery for BTC-compressed images

To ensure the integrity of images compressed using block truncation coding (BTC), a tamper detection and image recovery scheme is proposed in this paper. In this scheme, the size of the authentication data can be adaptively selected according to the user’s requirement. The authentication data is embedded in the value differences of the quantization levels in each BTC-compressed image block. Multiple copies of the recovery data are embedded into the bit maps of the smooth blocks. Experimental results show that the proposed scheme performs well in terms of detection precision and the embedded image quality. Meanwhile, the tampered areas can be roughly recovered by using the proposed scheme.     

Grayscale image coding using optimal pixel grouping and adaptive multi-grouping division block truncation coding

Multimedia Tools and Applications - An efficient grayscale image coding scheme based on block truncation coding (BTC) is proposed. The optimal pixel grouping mechanism and the multi-grouping...     

Modified block truncation coding for image compression

This paper presents a modified block truncation coding scheme for the compression of images. We first design a set of binary edge patterns, which are visually significant, to approximate the bit plane of an image block. An interblock coding scheme, utilizing the spatial correlation between neighboring blocks, is then developed for coding of the sample mean and standard deviation of a block. Simulation results indicate that the bit rate is significantly reduced without introducing noticeable degradation in the reconstructed images.     

低空突防用数字地形数据压缩研究

地形数据是低空突防系统最主要的信息来源之一,由于机载条件对电子设备的重量和体积有很大的限制,因此地形数据必须按低空防的要求进行压缩以减小其存储空间,本文探讨并比较了采用。ＬＰＣ,ＤＣＴ和ＢＴＣ三种压缩算法运行低空防用地形数据压缩的特点,文中首先设计了一个三阶预测器对地形数据进行ＬＰＣ压缩,其次给出了ＤＣＴ编码的恢复误差的估计式,并根据该估计式按低空防要求选取量化矩阵以压缩地形数据,最后提出了一种块间自适应的ＢＴＣ算法,仿真结果表明,块间自适应ＢＴＣ算法的综合压缩的性能较合乎低空突防的要求。     

Lossless data hiding for color images based on block truncation coding

In this paper, we present a novel, reversible steganographic method, which can reconstruct an original image effectively after extracting the embedded secret data. The proposed reversible hiding method aims at BTC (block truncation coding)-compressed color images. Conventionally, each block of a color image compressed by BTC requires three bitmaps and three pairs of quantization levels for reconstruction. In order to improve the compression rate, a genetic algorithm (GA) is applied to find an approximate optimal common bitmap to replace the original three. The secret data then are embedded in the common bitmap and the quantization levels of each block use the properties of side matching and the order of these quantization levels to achieve reversibility. The experimental results demonstrate that the proposed method is practical for BTC-compressed color images and can embed more than three bits in each BTC-encoded block on average.     

Lapped transform‐based codec for frame‐memory reduction in super‐quality LCD overdrive

Abstract— Overdrive is commonly used to reduce the liquid‐crystal response time and motion blur in liquid‐crystal displays (LCDs). However, overdrive requires a large frame memory in order to store the previous frame for reference. In this paper, a lapped transform‐based codec (LTC) is proposed to reduce the frame memory needed for LCD overdrive. In the latest literature, a directional prediction‐based codec (DPC) employs eight directional predictions, which takes up a large percentage of the computational complexity of the codec and does not consider the de‐correlation of the inter‐blocks. Therefore, the LTC first uses the lapped transform to decompose the correlation of the inter‐blocks in the YUV color space. A hadamard transform is then used for energy compaction. The reordered coefficients are pre‐quantized and encoded using the proposed adaptive bit‐plane coding (ABPC) method for a simple hardware implementation. The simulation results show that the proposed LTC significantly improves the DPC in both subjective and objective performance and outperforms the block truncation coding (BTC) and adaptive multi‐level BTC (AM‐BTC), which have been described in the literature.     

A secure and robust digital signature scheme for JPEG2000 image authentication

In this paper, we present a secure and robust content-based digital signature scheme for verifying the authenticity of JPEG2000 images quantitatively, in terms of a unique concept named lowest authenticable bit rates (LABR). Given a LABR, the authenticity of the watermarked JPEG2000 image will be protected as long as its final transcoded bit rate is not less than the LABR. The whole scheme, which is extended from the crypto data-based digital signature scheme, mainly comprises signature generation/verification, error correction coding (ECC) and watermark embedding/extracting. The invariant features, which are generated from fractionalized bit planes during the procedure of embedded block coding with optimized truncation in JPEG2000, are coded and signed by the sender's private key to generate one crypto signature (hundreds of bits only) per image, regardless of the image size. ECC is employed to tame the perturbations of extracted features caused by processes such as transcoding. Watermarking only serves to store the check information of ECC. The proposed solution can be efficiently incorporated into the JPEG2000 codec (Part 1) and is also compatible with Public Key Infrastructure. After detailing the proposed solution, system performance on security as well as robustness will be evaluated.