A novel context sensitive multilevel thresholding for image segmentation

Most of the traditional histogram-based thresholding techniques are effective for bi-level thresholding and unable to consider spatial contextual information of the image for selecting optimal threshold. In this article a novel thresholding technique is presented by proposing an energy function to generate the energy curve of an image by taking into an account the spatial contextual information of the image. The behavior of this energy curve is very much similar to the histogram of the image. To incorporate spatial contextual information of the image for threshold selection process, this energy curve is used as an input of our technique instead of histogram. Moreover, to mitigate multilevel thresholding problem the properties of genetic algorithm are exploited. The proposed algorithm is evaluated on the number of different types of images using a validity measure. The results of the proposed technique are compared with those obtained by using histogram of the image and also with an existing genetic algorithm based context sensitive technique. The comparisons confirmed the effectiveness of the proposed technique.     

利用角关联计算符合相加修正因子

提供了一种理论计算符合相加修正因子的方法。根据级联衰变的两个γ光子之间角度服从某一分布，利用蒙卡罗随机模拟方法，理论计算＾６０Ｃｏ点源离探测器为某一高度时各γ光子的符合相加修正因子。结果表明，符合相加修正因子随高度的增加而减小。     

计算机视觉技术在零件尺寸测量中的应用

介绍了一种应用计算机视觉技术检测机械零件参数的测量方法。以面阵CCD为图像传感器,通过图像采集卡将机械零件的二维图像输入到计算机中。在对原始输入图像进行直方图校正和边缘保持滤波处理后,对得到的较为平滑的零件图像进行边缘检测。利用图像边缘灰度突变的特性,提出了一种结合梯度算子的快速边缘检测方法。并据此计算出零件的各参数值。此种测量方法非常适合于微小、易形变等接触测量难以准确测量的机械零件的参数检测,具有广阔的应用前景。     

Analog and digital image enhancement using fuzzy expert systems

 Image enhancement is a field that is being used in various areas and disciplines. Advances in computers, microcontrollers and DSP boards have opened new horizons to digital image processing, and have opened many avenues to the design and implementation of new innovative techniques. This paper compares image enhancement via the modification of the probability density function of the gray levels with the new techniques that involves the use of knowledge-base (fuzzy expert) systems that are capable of mimicking the behavior of a human expert. A fuzzy expert system based software for image enhancement, called SmartPhotoLab has been introduced for the above purpose. Present address: A. El-Osery Dept. of Electrical Engineering, New Mexico Tech, Workman Center Rm. 247 801 Leroy place, Socorro, NM 87801 e-mail: elosery@ee.nmt.edu. This work was supported in parts by NASA grants no. NAG2–1196 and 2-1480.     

A high-payload,reversible data hiding scheme based on histogram modification in JPEG bitstream

In this paper, we have presented a high-payload, reversible data hiding scheme that is focused on embedding secret data into joint photographic experts group (JPEG) bitstream by using histogram modification. In JPEG, for AC coefficients, 162 different variable length codes (VLCs) are defined and assigned by Huffman coding for all 162 run/size possibilities. After parsing VLC usage in the bitstream, we generated a histogram of run/size. According to a peak point and the nearest zero point of the histogram, the secret data were embedded by modifying the corresponding VLC values slightly. The experimental results and comparing the performance of our scheme with those of other existing schemes demonstrated that the proposed scheme preserved the quality of the image with no distortion and achieved the goal of high embedding capacity.     

Reversible watermarking method based on asymmetric-histogram shifting of prediction errors

This paper tries to provide a new perspective for the research of reversible watermarking based on histogram shifting of prediction errors. Instead of obtaining one prediction error for the current pixel, we calculate multiple prediction errors by designing a multi-prediction scheme. An asymmetric error histogram is then constructed by selecting the suitable one from these errors. Compared with traditional symmetric histogram, the asymmetric error histogram reduces the amount of shifted pixels, thus improving the watermarked image quality. Moreover, a complementary embedding strategy is proposed by combining the maximum and minimum error histograms. As the two error histograms shift in the opposite directions during the embedding, some watermarked pixels will be restored to their original values, thus the image quality is further improved. Experimental findings also show that the proposed method re-creates watermarked images of higher quality that carry larger embedding capacity compared to conventional symmetric histogram methods, such as Tsai et al.’s and Luo et al.’s works.     

基于直方图约束的匹配图象改善方法

针对导弹精确制导问题,研究了提高景象匹配定位准确性和可靠性的方法。对于相同地区不同光线照射下,由于图象获取方法不同,往往会造成匹配图象参数产生差异,进行影响景象匹配准确性和可靠性,通过调整图象直方图,使它们基本表现一致,从而减少了图象差异,提高了匹配准确性和可靠性。通过比较发现,由于匹配图象处理后,可使基准图和实时图的信噪比减小28．6％,因此,该方法有利于改善景象匹配性能。     

航空照片中道路交叉口的自动检测

本文提出了一种从航空照片中提取主要道路交叉口的方法.本方法是基于道路交叉的几何-统计模型来实现自动检测的.首先检测可能存在道路交叉口的候选区域,然后再针对候选区做道路交叉口参数的提取,最后根据道路交叉口的模型进行证实.实验证明该方法具有检测准确性高、速度快、抗噪能力及鲁棒性强的优点.     

A novel fast intra algorithm for VVC based on histogram of oriented gradient

The latest Versatile Video Coding (VVC) standard incorporates a series of effective and complex new intra coding tools, which obtains superior coding efficiency than the High Efficiency Video Coding (HEVC). However, this makes the intra coding more complicated and time-consuming. A fast algorithm for VVC from two aspects of fast mode decision and fast partition decision is proposed in this paper. For the fast mode decision, the relationship between bins with Histogram of Oriented Gradient (HOG) and intra modes is created for the mode selection, decreasing the planar modes for SATD and RDO. Moreover, we analyze the maximum bins to determine the final modes, and we use the modes of left and upper blocks as a reference for the current CU, which can early terminate RDO. Moreover, a two-step fast partition algorithm is proposed based on HOG for fast partition decision, in which two thresholds are investigated to control the uniformity of textures. The proposed fast algorithm is implemented on the VVC test model, and the experimental results show that it can achieve 69.07% time savings with only 2.96% BDBR increases averagely, which outperforms other relatively existing state-of-the-art methods. Moreover, to convince the universality of our algorithm, we further implement our method in Fraunhofer Versatile Video Encoder (VVenc) and Fraunhofer Versatile Video Decoder (VVdec), which have five settings to control the trade-off between encoding quality and efficiency for intra coding. The fast intra mode decision algorithm and fast partition algorithm decrease the complexity of intra coding for both VTM and VVenc, which shows the efficiency and universality of the proposed fast partition and fast mode decision algorithms.