A GLCM-Feature-Based Approach for Reversible Image Transformation

Recently,a reversible image transformation(RIT)technology that transforms a secret image to a freely-selected target image is proposed.It not only can generate a stego-image that looks similar to the target image,but also can recover the secret image without any loss.It also has been proved to be very useful in image content protection and reversible data hiding in encrypted images.However,the standard deviation(SD)is selected as the only feature during the matching of the secret and target image blocks in RIT methods,the matching result is not so good and needs to be further improved since the distributions of SDs of the two images may be not very similar.Therefore,this paper proposes a Gray level co-occurrence matrix(GLCM)based approach for reversible image transformation,in which,an effective feature extraction algorithm is utilized to increase the accuracy of blocks matching for improving the visual quality of transformed image,while the auxiliary information,which is utilized to record the transformation parameters,is not increased.Thus,the visual quality of the stego-image should be improved.Experimental results also show that the root mean square of stego-image can be reduced by 4.24%compared with the previous method.

Reversible Watermarking Method with Low Distortion for the Secure Transmission of Medical Images

In telemedicine,the realization of reversible watermarking through information security is an emerging research field.However,adding watermarks hinders the distribution of pixels in the cover image because it creates distortions(which lead to an increase in the detection probability).In this article,we introduce a reversible watermarking method that can transmit medical images with minimal distortion and high security.The proposed method selects two adjacent gray pixels whose least significant bit(LSB)is different from the relevant message bit and then calculates the distortion degree.We use the LSB pairing method to embed the secret matrix of patient record into the cover image and exchange pixel values.Experimental results show that the designed method is robust to different attacks and has a high PSNR(peak signal-to-noise ratio)value.The MRI image quality and imperceptibility are verified by embedding a secret matrix of up to 262,688 bits to achieve an average PSNR of 51.657 dB.In addition,the proposed algorithm is tested against the latest technology on standard images,and it is found that the average PSNR of our proposed reversible watermarking technology is higher(i.e.,51.71 dB).Numerical results show that the algorithm can be extended to normal images and medical images.

Slicing Method for Reverse Engineering Based on Image Mosaic

Reverse engineering dealing with images is traditionally based on image processing and contour recognition. A new method is presented based on the combination of sectional slicing with image mosaic. Sectional contours of the target object are generated by colorful liquid or laser scanning, these images from different views are fused into a set of complete cross-sectional images, thereby the whole practical model is reconstructed in 3D space.

An improved reverse time migration for subsurface imaging over complex geological structures:A numerical study

In seismic exploration,it is a critical task to image and interpret different seismic signatures over complex geology due to strong lateral velocity contrast,steep reflectors,overburden strata and dipping flanks.To understand the behavior of these seismic signatures,nowadays Reverse Time Migration(RTM)technique is used extensively by the oil&gas industries.During the extrapolation phase of RTM,the source wavefield needs to be saved,which needs high storage memory and large computing time.These two are the main obstacles of RTM for production use.In order to overcome these disadvantages,in this study,a second-generation improved RTM technique is proposed.In this improved form,a shift operator is introduced at the time of imaging condition of RTM algorithm which is performed automatically both in space and time domain.This effort is made to produce a better-quality image by minimizing the computational time as well as numerical artefacts.The proposed method is applied over various benchmark models and validated by implementing over one field data set from the Jaisalmer Basin,India.From the analysis,it is observed that the method consumes a minimum of 45%less storage space and reduce the execution time by 20%,as compared to conventional RTM.The proposed RTM is found to work efficiently in comparison to the conventional RTM both in terms of imaging quality and minimization of numerical artefacts for all the benchmark models as well as field data.

一种改进的SAR图像舰船目标超像素快速检测算法

合成孔径雷达(Synthetic Aperture Radar,SAR)能够不受天气和环境影响,长时间、远距离地高效对目标区域进行探测和数据采集来获取高分辨的观测数据,同时SAR可以多极化、多波段进行观测来获取丰富可靠的信息,以上特性使得SAR在舰船目标检测领域发挥着重要作用。针对传统超像素级恒虚警率检测算法运行效率低的问题,在超像素分割模块提出了一种基于Gamma分布的快速非迭代聚类算法。该算法使用优先级队列来动态实时更新聚类中心,实现了聚类过程的非迭代运算,并且针对SAR图像特点基于Gamma分布改进距离度量,通过衡量图块之间的相似度代替彩色空间距离度量,使得该算法更适合处理灰度图像。针对多目标邻近干扰的问题,本文在CFAR检测模块选用对背景杂波拟合效果好的截断Gamma分布模型。将改进的超像素分割算法与基于截断Gamma分布的检测算法结合,最终设计了一种改进的SAR图像目标超像素快速检测算法。经实验验证,本文提出的改进超像素分割算法在保证分割性能优异的同时,复杂度明显降低;另外截断Gamma分布尽可能地保留了真实的海杂波样本,在统计模型构建上呈现出更高的精确度和更佳的拟合效果,对后续检测算法更有利;在多目标邻近的实测SAR图像中,本文改进的目标超像素快速检测算法具有较高的检测率和执行效率。

改进星鸦优化算法的无刷直流电机控制研究

针对无刷直流电机双闭环控制系统存在响应速度慢、控制精度低等问题,标准的星鸦优化算法(NOA)收敛速度较慢,研究一种改进星鸦优化算法(INOA)优化PID控制器参数整定策略。利用佳点集初始化种群,丰富星鸦种群多样性;加入随机惯性权重,用于平衡INOA的探索与开发;运用透镜成像反向学习策略对最优解进行贪婪学习,扩充最优解区间。选取4组基准测试函数对INOA性能进行评估,进一步证明改进算法的有效性和可行性。在空载、突加转速和突加负载3种条件下进行仿真实验,仿真结果表明,相较于传统PID控制与模糊PID控制,采用改进星鸦优化算法的PID调速系统转速响应更快、控制精度更高。

基于像素调制自适应编码密文域的可逆信息隐藏算法

针对图像信息隐藏不能产生理想的有效负载问题,提出一种基于像素调制自适应编码密文域的可逆信息隐藏算法。首先,对灰度图像做块间置乱并进行像素调制预处理,设计块内像素位置变换矩阵保证分块置乱前后中心像素的预测误差不变。接着,利用最邻近像素差分方法保持加密图像块内的空间冗余,根据预测误差的频率自适应生成哈夫曼编码,并对比哈夫曼编码中比特位将信息嵌入到预留空间中。最后,对所提出算法进行实验分析,实验结果表明:提出的算法具有可逆性和信息分离性,与自适应差分图像恢复算法相比,平均嵌入率提高了0.299 bpp。

MRI中DWI序列对可逆性胼胝体压部病变综合征的诊断价值

目的 探讨磁共振(MRI)中扩散加权成像(DWI)序列对可逆性胼胝体压部病变综合征(RESLES)的诊断价值。方法 回顾性纳入2021年5月至2023年4月医院30例RESLES患者为RESLES组,另纳入同期医院30例胼胝体压部缺血性脑梗死患者为对照组,两组患者入院时均接受MRI-DWI序列扫描检查,对比两组MRI表现特点及成像参数[表观扩散系数(ADC)],并绘制ROC分析ADC值对RESLES的诊断价值。结果 RESLES组患者病灶集中在胼胝体压部中线部,且在胼胝体压部中线处呈对称性排列,多为单发病灶,病灶形态相对规则,MRI扫描T1WI稍低信号,T2WI稍高信号,DWI高信号;对照组患者病变大都偏离胼胝体压部一侧,大都为多发病灶,病灶形态相对不规则,MRI扫描低信号,T2WI、DWI高信号;RESLES组ADC值比对照组低(P<0.05);绘制ROC曲线结果显示,ADC值诊断RESLES的AUC=0.767,具有一定诊断价值。结论 MRI扫描检查可清晰显示RESLES患者脑部病变数量、形态、分布情况等特征,能够为R ESLES诊断提供重要依据,同时DWI序列参数对RESLES、胼胝体压部缺血性脑梗死具有一定鉴别诊断价值。

Reversible Data Hiding in Encrypted Image Based on Block Classification Permutation

Recently,reversible data hiding in encrypted image(RDHEI)has attracted extensive attention,which can be used in secure cloud computing and privacy protection effectively.In this paper,a novel RDHEI scheme based on block classification and permutation is proposed.Content owner first divides original image into non-overlapping blocks and then set a threshold to classify these blocks into smooth and non-smooth blocks respectively.After block classification,content owner utilizes a specific encryption method,including stream cipher encryption and block permutation to protect image content securely.For the encrypted image,data hider embeds additional secret information in the most significant bits(MSB)of the encrypted pixels in smooth blocks and the final marked image can be obtained.At the receiver side,secret data will be extracted correctly with data-hiding key.When receiver only has encryption key,after stream cipher decryption,block scrambling decryption and MSB error prediction with threshold,decrypted image will be achieved.When data hiding key and encryption key are both obtained,receiver can find the smooth and non-smooth blocks correctly and MSB in smooth blocks will be predicted correctly,hence,receiver can recover marked image losslessly.Experimental results demonstrate that our scheme can achieve better rate-distortion performance than some of state-of-the-art schemes.

The brightness reversal of submarine sand waves in “HJ-1A/B” CCD sun glitter images

The brightness reversal of submarine sand waves appearing in the small satellite constellation for environ- ment and disaster monitoring and forecasting （＂HJ- 1A/B＂） CCD sun glitter images can affect the observation and depth inversion of sand wave topography. The simulations of the normalized sun glitter radiance on the submarine sand waves confirm that the reversal would happen at a specific sensor viewing angle, defined as the critical angle. The difference between the calculated critical angle position and the reversal position in the image is about 1＇, which is excellent in agreement. Both the simulation and actual image show that sand wave crests would be indistinct at the reversal position, which may cause problems when using these sun glitter images to analyze spatial characteristics and migration of sand waves. When using the sun glitter image to obtain the depth inversion, one should take the advantage of image properties of sand waves and choose the location in between the reversal position and the brightest position. It is also necessary to pay attention to the brightness reversal when using ＂HI-1A/B＂ CCD images to analyze other oceanic features, such as internal waves, oil slicks, eddies, and ship wakes.

A time reversal damage imaging method for structure health monitoring using Lamb waves

This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably.

Efficient hybrid method for time reversal superresolution imaging

An efficient hybrid time reversal（TR） imaging method based on signal subspace and noise subspace is proposed for electromagnetic superresolution detecting and imaging. First, the locations of targets are estimated by the transmitting-mode decomposition of the TR operator（DORT） method employing the signal subspace. Then, the TR multiple signal classification（TR-MUSIC）method employing the noise subspace is used in the estimated target area to get the superresolution imaging of targets. Two examples with homogeneous and inhomogeneous background mediums are considered, respectively. The results show that the proposed hybrid method has advantages in CPU time and memory cost because of the combination of rough and fine imaging.

Microstructural changes in memory and reticular formation neural pathway after simple concussion

Patients with concussion often present with temporary disturbance of consciousness. The microstructural and functional changes in the brain associated with concussion, as well as the relationship with transient cognitive disorders, are currently unclear. In the present study, a rabbit model of simple concussion was established. Magnetic resonance-diffusion tensor imaging results revealed that the corona radiata and midbrain exhibited significantly decreased fractional anisotropy values in the neural pathways associated with memory and the reticular formation. In addition, the apparent diffusion coefficient values were significantly increased following injury compared with those before injury. Following a 1-hour period of quiet rest, the fractional anisotropy values significantly increased, and apparent diffusion coefficient values significantly decreased, returning to normal pre-injury levels. In contrast, the fractional anisotropy values and apparent diffusion coefficient values in the corpus callosum, thalamus and hippocampus showed no statistical significant alterations following injury. These findings indicate that the neural pathways associated with memory and the reticular formation pathway exhibit reversible microstructural white matter changes when concussion occurs, and these changes are exhibited to a different extent in different regions.

Dual Image Reversible Data Hiding by Modifying Least Significant-Bit Matching Revisited Rules

The concept of dual image reversible data hiding（DIRDH） is the technique that can produce two camouflage images after embedding secret data into one original image.Moreover,not only can the secret data be extracted from two camouflage images but also the original image can be recovered.To achieve high image quality,Lu et al.＇s method applied least-significant-bit（LSB） matching revisited to DIRDH.In order to further improve the image quality,the proposed method modifies LSB matching revisited rules and applies them to DIRDH.According to the experimental results,the image quality of the proposed method is better than that of Lu et al.＇s method.

Reversible Data Hiding in Classification-Scrambling Encrypted-Image Based on Iterative Recovery

To improve the security and quality of decrypted images,this work proposes a reversible data hiding in encrypted image based on iterative recovery.The encrypted image is firstly generated by the pixel classification scrambling and bit-wise exclusive-OR(XOR),which improves the security of encrypted images.And then,a pixel-typemark generation method based on block-compression is designed to reduce the extra burden of key management and transfer.At last,an iterative recovery strategy is proposed to optimize the marked decrypted image,which allows the original image to be obtained only using the encryption key.The proposed reversible data hiding scheme in encrypted image is not vulnerable to the ciphertext-only attack due to the fact that the XOR-encrypted pixels are scrambled in the corresponding encrypted image.Experimental results demonstrate that the decrypted images obtained by the proposed method are the same as the original ones,and the maximum embedding rate of proposed method is higher than the previously reported reversible data hiding methods in encrypted image.

A Reversible Data Hiding Algorithm Based on Image Camouflage and Bit-Plane Compression

Reversible data hiding in encrypted image(RDHEI)is a widely used technique for privacy protection,which has been developed in many applications that require high confidentiality,authentication and integrity.Proposed RDHEI methods do not allow high embedding rate while ensuring losslessly recover the original image.Moreover,the ciphertext form of encrypted image in RDHEI framework is easy to cause the attention of attackers.This paper proposes a reversible data hiding algorithm based on image camouflage encryption and bit plane compression.A camouflage encryption algorithm is used to transform a secret image into another meaningful target image,which can cover both secret image and encryption behavior based on“plaintext to plaintext”transformation.An edge optimization method based on prediction algorithm is designed to improve the image camouflage encryption quality.The reversible data hiding based bit-plane level compression,which can improve the redundancy of the bit plane by Gray coding,is used to embed watermark in the camouflage image.The experimental results also show the superior performance of the method in terms of embedding capacity and image quality.

A Novel Image Encryption Scheme Based on Reversible Cellular Automata

In this paper,a new scheme for image encryption is presented by reversible cellular automata.The presented scheme is applied in three individual steps.Firstly,the image is blocked and the pixels are substituted by a reversible cellular automaton.Then,image pixels are scrambled by an elementary cellular automata and finally the blocks are attached and pixels are substituted by an individual reversible cellular automaton.Due to reversibility of used cellular automata,decryption scheme can reversely be applied.The experimental results show that encrypted image is suitable visually and this scheme has satisfied quantitative performance.

基于Image ware和UG的摩托车覆盖件曲面逆向设计

先运用Image ware软件较快的对点云进行去噪、稀疏、提取特征线等操作,然后再利用UG软件强大的曲面造型功能完成对摩托车覆盖件三维曲面的构造及与样品间精度误差的检查。Image ware软件与UG软件结合运用不但节省了设计时间,还减少了设计误差。因此,逆向设计是一项实用性很强的技术,已成为当今工业设计中一项不可或缺的技术。

The Image Conversion in Optical Echo-Holography by External Electromagnetic Standing Waves

The recording and playback of information using a reverse stimulated photon—echo hologram when exposed to the recording medium pulse of non-resonant electromagnetic standing wave was considered. It was shown that the spatial intensity distribution in stimulated echo hologram response depended on the electric field intensity of non-resonant standing wave that allowed controlling by a reproducible image.

煤矿冲击地压和煤与瓦斯突出事故自动发现与报警方法研究

煤矿冲击地压和煤与瓦斯突出自动感知报警方法是及时发现事故并应急救援,减少人员伤亡,避免或减少瓦斯和煤尘爆炸等次生事故发生,遏制事故迟报、漏报和瞒报的有效措施。煤矿冲击地压事故感知难,目前还没有煤矿冲击地压事故自动发现和报警方法,煤矿冲击地压事故主要靠人工发现。目前仅有基于甲烷、风速和风向传感器的煤与瓦斯突出自动报警方法,但存在响应速度慢、甲烷传感器损毁前监测不到甲烷浓度大幅升高等问题。提出了煤矿冲击地压和煤与瓦斯突出图像感知报警方法:根据煤矿冲击地压和煤与瓦斯突出温度、颜色、深度、掩埋等图像特征,识别煤矿冲击地压和煤与瓦斯突出;再根据巷道空间和采掘工作面的甲烷浓度变化,区分冲击地压和煤与瓦斯突出,如果甲烷浓度大面积迅速升高,则判定为煤与瓦斯突出,否则判定为冲击地压。该方法具有直观、响应速度快、非接触、监测范围广、简单可靠等优点,可直观地记录煤矿冲击地压和煤与瓦斯突出真实情况;当煤矿冲击地压和煤与瓦斯突出事故报警后,调度室值班人员可以通过录像,立即确认事故,及时进行应急救援。提出了减少煤矿冲击地压和煤与瓦斯突出抛出的煤岩对图像感知影响的方法:摄像机多点布置,摄像机设置在较高位置,视频数据及时传输,甲烷传感器多点布置等。