JPEG2000图像压缩标准及其关键算法的应用

JPEG2000是为适应不断发展的图像压缩应用而出现的新的静止图像压缩标准。阐述了JPEG2000图像编码系统的实现过程,对其中采用的基本算法和关键技术进行了描述,介绍了这一新标准的特点及应用场合,并对其性能进行了分析。     

包装印刷中JPEG2000标准实现的研究

对包装印刷装潢图像用Visual C 实现了最新图像压缩标准JPEG2000对其进行压缩,并得出了软件实现功能和对装潢图像的压缩、存储和传输结论,对装潢图像的压缩保存和传输具有一定的实际意义.     

包装印刷中JPEG2000标准实现框架的研究

介绍了最新的静止图像压缩标准JPEG2000的优点,设计了图像压缩系统在包装印刷领域内应用的实现框架,从而为图像的存储和传输提供一可借鉴的途径.     

基于码率预分配编码技术的高分辨率航测图像压缩

由于需要对大面阵航空CCD相机带来的庞大航测图像数据进行压缩,在研究多种图像压缩算法的基础上提出了一种基于比特位平面编码的码率预分配图像压缩算法(RPCA)。首先将图像进行多级整数小波变换,以去除图像像素之间相关冗余。根据率失真理论并结合各个子带对图像重建质量的重要性原则,编码前事先确定每个子带在总码率一定的情况下各个子带在实际编码中应当分配的码率大小,再利用自适应MQ算术编码对每个子带比特平面进行熵编码,从而得到细致的嵌入式码流。实验仿真结果表明,该RPCA码率分配精准,图像压缩质量与JPEG2000标准相当,且支持无损到有损的任意倍率图像压缩,但复杂度低于JPEG2000标准,适合于硬件的高速实现。     

Illumination-tolerant face verification of low-bit-rate JPEG2000 wavelet images with advanced correlation filters for handheld devices

Face recognition on mobile devices, such as personal digital assistants and cell phones, is a big challenge owing to the limited computational resources available to run verifications on the devices themselves. One approach is to transmit the captured face images by use of the cell-phone connection and to run the verification on a remote station. However, owing to limitations in communication bandwidth, it may be necessary to transmit a compressed version of the image. We propose using the image compression standard JPEG2000, which is a wavelet-based compression engine used to compress the face images to low bit rates suitable for transmission over low-bandwidth communication channels. At the receiver end, the face images are reconstructed with a JPEG2000 decoder and are fed into the verification engine. We explore how advanced correlation filters, such as the minimum average correlation energy filter [Appl. Opt. 26, 3633 (1987)] and its variants, perform by using face images captured under different illumination conditions and encoded with different bit rates under the JPEG2000 wavelet-encoding standard. We evaluate the performance of these filters by using illumination variations from the Carnegie Mellon University's Pose, Illumination, and Expression (PIE) face database. We also demonstrate the tolerance of these filters to noisy versions of images with illumination variations.     

一种基于小波变换的遥感图像压缩算法

为验证图像压缩算法122.0-B-0对遥感图像的有效性,在对该算法进行了较为详细的研究后,对该算法进行了软件实现,然后将该算法与JPEG2000、SPIHT算法在压缩效率及压缩速度上进行了比较.实验结果表明:该算法在较低码率下压缩性能与JPEG2000、SPIHT算法相当,在较高码率下压缩性能略微下降,但在相同码率下它的编码速度比JPEG2000快2倍左右,比SPIHT算法约快1.5倍左右,且编解码速度与码率成正比.该算法采用的编码方式相对简单,无反馈操作,可适应于不同内存大小的压缩系统,并采用分段编码有效地防止误码扩散,因此在空间飞行器上具有巨大的应用价值.     

Volumetric medical image compression using inter-slice correlation switched prediction approach

With the advancement in medical data acquisition and telemedicine systems, image compression has become an important tool for image handling, as the tremendous amount of data generated in medical field needs to be stored and transmitted effectively. Volumetric MRI and CT images comprise a set of image slices that are correlated to each other. The prediction of the pixels in a slice depends not only upon the spatial information of the slice, but also the inter-slice information to achieve compression. This article proposes an inter-slice correlation switched predictor (ICSP) with block adaptive arithmetic encoding (BAAE) technique for 3D medical image data. The proposed ICSP exploits both inter-slice and intra-slice redundancies from the volumetric images efficiently. Novelty of the proposed technique is in selecting the correlation coefficient threshold (T_ϒ) for switching of ICSP. Resolution independent gradient edge detector (RIGED) at optimal prediction threshold value is proposed for intra-slice prediction. Use of RIGED, which is modality and resolution independent, brings the novelty and improved performance for 3D prediction of volumetric images. BAAE is employed for encoding of prediction error image to resulting in higher compression efficiency. The proposed technique is also extended for higher bit depth volumetric medical images (16-bit depth) presenting significant compression gain of 3D images. The performance of the proposed technique is compared with the state-of-the art techniques in terms of bits per pixel (BPP) for 8-bit depth and was found to be 31.21%, 27.55%, 21.89%, and 2.39% better than the JPEG-2000, CALIC, JPEG-LS, M-CALIC, and 3D-CALIC respectively. The proposed technique is 11.86%, 8.56%, 7.97%, 6.80%, and 4.86% better than the M-CALIC, 3D CALIC, JPEG-2000, JPEG-LS and CALIC respectively for 16-bit depth image datasets. The average value of compression ratio for 8-bit and 16-bit image dataset is obtained as 3.70 and 3.11 respectively by the proposed technique.     

Very-high-quality image compression based on noise modeling

We present a new image compression method for very-high-quality lossy compression. This method caters for image data in regimes of (a) detector imperfections, which motivates a robust approach based on the median transform; and (b) noise, which is explicitly sought and separated out, since noise is inherently noncompressible. An in-depth assessment is carried out on real data, relative to the standard JPEG compression method. Comparable visual quality is based on 260:1 compression with the new method, and 40:1 compression with JPEG. The assessment procedure, based on the astronomical images used, is an objective approach for determining very-high-quality visual reconstructions. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 38–45, 1998     

Extreme-ultraviolet lensless Fourier-transform holography

We demonstrate 100-nm-resolution holographic aerial image monitoring based on lensless Fourier-transform holography at extreme-UV (EUV) wavelengths, using synchrotron-based illumination. This method can be used to monitor the coherent imaging performance of EUV lithographic optical systems. The system has been implemented in the EUV phase-shifting point-diffraction interferometer recently developed at Lawrence Berkeley National Laboratory. Here we introduce the idea of the holographic aerial image-recording technique and present imaging performance characterization results for a 10x Schwarzschild objective, a prototype EUV lithographic optic. The results are compared with simulations, and good agreement is obtained. Various object patterns, including phase-shift-enhanced patterns, have been studied. Finally, the application of the holographic aerial image-recording technique to EUV multilayer mask-blank defect characterization is discussed.     

Red-green-blue interferometer for the metrology of discontinuous structures

Discontinuous surface profiles, e.g., diffractive optical elements (DOEs), are commonly measured by white-light interferometry. White-light interferometry needs significantly more memory capacity and computer time than does phase-shifting interferometry; there are approximately ten times more frames to be taken to gather the required information about the object under test. But usually the grooves of the DOEs are too deep for single-wavelength phase-shifting interferometry. Here we show how phase-shifting techniques can be applied to DOEs. For this purpose three interference patterns are recorded simultaneously by a three-chip color CCD camera at three wavelengths (Red-green-blue). It is possible to calculate separately the optical path difference at each pixel from the three phase patterns modulo 2pi. The algorithms used and experimental results are presented.     

JPEG2000中可逆整数5/3小波变换及其在DSP上的实现

JPEG2000中的可逆小波变换利用整数到整数的小波变换技术。这种变换通过一维双通道完 全重构通用极大值滤波带实现,对图像块进行5/3滤波,获得的低通信号进行再滤波,得到的系数通过组合就成为JPEG2000文件数据。通过TMS320VC5402芯片实现这种滤波并优化汇编程序设计。该技术可实现对图像的有损和无损压缩,在其他图像处理领域也可以直接利用。     

CCD传感器噪声对遥感影像无损压缩的影响

为分析CCD传感器噪声对遥感影像无损压缩的影响,选取ISO/IEC标准图像和UK-DMC多光谱影像作为测试图像,根据CCD传感器噪声模型,在测试图像上添加CCD传感器模拟噪声,采用JPEG2000-Lossless无损压缩算法对不同污染程度的噪声图像进行压缩处理,并对不同污染程度的噪声影像无损压缩比进行比较分析.而后,在多光谱遥感影像上添加模拟的混合噪声,分析CCD噪声对星地间数据传输效率的影响.实验结果表明,CCD传感器噪声对所获取影像的污染会降低遥感影像的无损压缩比和星地间数据传输效率,以泊松噪声为模型的散粒噪声与读出噪声对影像无损压缩的影响最大,以高斯噪声为模型的热噪声与暗电流噪声的影响次之,由于CCD器件工艺问题引发的脉冲噪声对无损压缩的影响最小.     

Efficient colour image compression using fusion approach

The aim of image compression endeavour is to reduce the total data required to represent the image, which, in turn, decreases the demand of transmission bandwidth and storage space. In this work, we propose an image fusion based idea that can be exploited extensively to reduce the file size of JPEG compressed image further. Before performing the JPEG compression, we compute both intensity and a subsampled colour representation of the image undergoing compression. Then, similar to the JPEG compression, discrete cosine transformation, quantisation and entropy coding processes are applied on these images and stored in a single image file container. In the decoder, these two images are reconstructed and fused to obtain the resultant decoded image. Our experiments show that the proposed method does meet the lower storage and bandwidth requirement by reducing the average bits per pixel of the encoded image than that of the JPEG compressed image.     

基于EALCD的数字全息的研究

采用一种新的数字全息再现方法,将电荷耦合器件CCD与电寻址液晶EALCD相结合实现数字全息的再现.同时将数字图像处理技术与数字全息术相结合,应用MATLAB软件对记录的全息图进行数字图像处理,实验结果表明,该方法简单快速.通过图像增强等方法对全息图进行数字图像处理,在全息再现中,全息干涉图的对比度得到了显著的提高,有利于全息干涉条纹的自动判读.     

Polarization microscopy by use of digital holography: application to optical-fiber birefringence measurements

We present a digital holographic microscope that permits one to image polarization state. This technique results from the coupling of digital holographic microscopy and polarization digital holography. The interference between two orthogonally polarized reference waves and the wave transmitted by a microscopic sample, magnified by a microscope objective, is recorded on a CCD camera. The off-axis geometry permits one to reconstruct separately from this single hologram two wavefronts that are used to image the object-wave Jones vector. We applied this technique to image the birefringence of a bent fiber. To evaluate the precision of the phase-difference measurement, the birefringence induced by internal stress in an optical fiber is measured and compared to the birefringence profile captured by a standard method, which had been developed to obtain high-resolution birefringence profiles of optical fibers.     

An image compression method based on multiple models for the probabilities of patterns

This article proposes an image compression method based on multiple models for the probabilities of patterns (MMPP method) to encode a gray‐level image f. First, the MMPP method employs a median edge detector (MED) to reduce the entropy of f. The intensities of two adjacent pixels in an image are usually close to each other. A base switching transformation (BST) is then used to lessen the spatial redundancy of f. Finally, the arithmetic encoding method is applied to further encode the data generated after the processing of MED and BST. To reduce the memory space required to hold f, the MMPP method classifies the data and then compresses the data in each cluster by the arithmetic encoding method based on different probability tables. The experimental results show that mostly the MMPP method can provide better efficiency in memory space than the lossless JPEG 2000 method does. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 362–368, 2009     

Three-dimensional Displacement Analysis by Windowed Phase-shifting Digital Holographic Interferometry

Abstract:  Phase-shifting digital holography is a new method for measuring the displacement distribution on the surface of an object. The authors previously proposed a windowed phase-shifting digital holographic interferometry (windowed PSDHI). This method provides accurate displacement distributions by decreasing the effect of speckle patterns. In this study, the method is extended to analyse three-dimensional displacement components in a microscope. Three object laser beams in the optical system are used. Four phase-shifted holograms are recorded for each object laser beam. The complex amplitude of each reconstructed light at the object is calculated by the Fresnel diffraction integral of the complex amplitude of the hologram. The reconstructed distance is obtained at the point with the maximum of the standard deviation of the intensities of the object reconstructed with changing the reconstruction distance. The three phase-difference values between before and after deformation provide the three-dimensional displacement components. Theoretical treatment and experimental results of three-dimensional displacement measurement using this method are shown.     

多光束移相干涉在镀膜平面形貌测量的应用研究

本文以光干涉原理为基础,分析多光束干涉原理特点及其在平面形貌(平面度)测量中应用可能,提出应用移相方法对被测镀高反膜表面进行调制,得到一系列被调制的干涉图样,经计算机对干涉图样进行自动采集和图像解包裹,获得被测表面的三维形貌数据,并通过实际测试验证了该方法的可行性和科学性。     

Development of a phase-displacement equation for panoramic interferometry

We developed the parametric equations that are needed to quantify the modulations in the sensitivity vector that occur when the phase-displacement equation is applied to make panoramic interferometric measurements. The measurement system relies on two collinear panoramic annular lenses, one to illuminate and the other to image their surroundings. When a coherent light source is used and a reference beam is added, interference occurs over the region of interest defined by the illuminating and viewing lenses. A holographic system is used to demonstrate the approach and quantify the analysis. We obtained interference fringes in real time by comparing holograms recorded before and after a section of cylindrical pipe is displaced relative to the measurement system. The annular images and the holographic fringes are acquired and stored digitally in a computer system, and image transformation algorithms are applied to remove optical distortions in the holographic patterns. Excellent agreement is obtained when the fringe loci are compared with those predicted on the basis of theory.     

抗几何攻击的强鲁棒性全息水印研究

目的寻找一种能够抵抗常见几何攻击的安全的水印算法。方法通过分析常见的水印算法,发现傅里叶-梅林变换域水印能够较好地满足抵抗常见几何攻击的需求。对水印图像进行双随机相位全息加密,通过密钥保障水印的安全性,通过把加密的水印嵌入到傅里叶-梅林变换域的方法,设计对比试验,研究含有水印的图像在平移、缩放、旋转、中值滤波、高斯噪声、椒盐噪声、压缩、打印扫描、打印拍摄攻击下提取水印质量的影响。结果水印能够抵抗常见的几何攻击,特别对平移、缩放、旋转组合几何攻击、打印扫描和打印拍摄有很好的效果。结论基于傅里叶-梅林变换的全息水印算法具有很好的鲁棒性,能够抵抗常见的几何攻击;具有很好的安全性,没有密钥不能对水印进行检测和去除。