一种基于噪声估计的彩色噪声滤除算法

在视频处理中，为了提高电视画面的清晰度，不但需要对亮度噪声进行滤除，对色度噪声的滤除也是必不可少的。文章的滤波算法是：先基于块操作对图像的噪声情况做一个大概的估计，然后根据估计的噪声情况对图像进行降噪或者不作处理。降噪的时候。对彩色脉冲和高斯噪声分别选择不同的阵噪算法。文章着重介绍了彩色脉冲噪声的滹除，该算法综合了线性和非线性矢量滤波，降噪效果明显,对高斯噪声采用矢量均值滤波。     

一种彩色视频图像序列的三维小波变换编码方法

该文给出了一种基于三维小波变换的彩色视频图像序列的编码方法。先将彩色视频图像序列的RGB(红绿蓝)色彩表示转换成YCbCr(亮度色度色度)表示,再将表示帧序的t坐标代换成z坐标,可将其看成是三维空间中的体。将其分成子块后,仿照二维图像小波变换的方法,对每个亮度色度分量做三维小波变换。变换后的各亮度色度分量的能量主要集中于低频波段,这些波段对该视频图像序列的视觉效果影响最大。将不同分量的各个不同波段按不同的精度量化并进行熵编码,可以达到去除帧内和帧间冗余,压缩数据的目的。试验表明,使用本方法可以达到较好的压缩效果。此方法较直观,速度也比较快。     

简单高效地用于SVC标准中的层间上采样滤波方案

结合人眼视觉系统的特点,提出了一种简单高效的用于SVC标准中的层间上采样滤波方案.基于人眼对图像亮度信息的变化比色度信息的变化要敏感的多这一特性,该方案通过简化图像色度分量的上采样滤波器来减少上采样插值运算量,以提高编码效率.对亮度分量采用复杂的6抽头滤波器,而对色度分量采用简单的双线性滤波器.实验结果表明,该方案在大幅度减少色度分量的上采样插值运算量的情况下,能够保持编码码率和PSNR性能几乎不变,可以被应用于可分级视频编码的层间空域插值算法中去.     

彩色图象在均匀色度空间中1比特／象素的矢量量化

本文将空间域矢量量化的方法运用于彩色图象。利用人类视觉对光谱的视觉特点,在均匀色度(L~*a~*6~*)空间中,对亮度分量和色度分量分别进行矢量量化。使彩色图象压缩到1bit/pel时,仍能保持较好的质量。     

基于SIFT和卡尔曼滤波的电子稳像技术研究

利用电子稳像方法去除抖动视频中的噪声是目前稳像技术的发展方向之一。文中首先介绍电子稳像的基本流程,随后使用SIFT提取图像中的特征点,以解决图像中存在缩放的问题。在经过运动一致性估计后计算运动参数,并使用Kalman滤波得到各帧的修正矢量。实验结果表明该方法能有效地去除随机运动分量而保持意向运动分量,得到稳定的视频。     

视频编码中的块运动估计算法分析（二）

4几种常用的快速搜索算法在视频编码标准中，运动估计以宏块为单位，在参考帧中以相对应的宏块为中心的搜索区域内进行搜索，寻找最佳匹配宏块，得到相应的运动矢量。运动估计只对亮度信号进行，色度信号借用亮度信号的估计结果。与此同时，MPEG2的TestModels”’－”‘建议在整像素运动估计搜索完毕后进行半像素精度的全搜索，即在规定的搜索区域内进行逐点搜索，得到一个匹配准则函数最小的整像素点，然后以该点为中心，取其周围线性内插得到8个半像素点进行全搜索，得到一个最佳匹配点。为了减少FS算法的运动搜索复杂度和数据读取复…     

一种高效的基于矢量量化的彩色视频图像压缩编码方法

针对彩色视频图像提出了一种DCT域内基于矢量量化的高效编码方法。为去掉彩色图像各分量间的相关性,首先将图像由RGB空间转换到YUV空间,然后根据人类视觉特征（HVS）对色度信号U、V进行了亚采样和平均化处理;对亮度信号Y则进行分块DCT变换,并根据HVS特征对变化域内的块矢量进行自适应分类,然后根据矢量的类型分别构造码矢和进行全局码书设计。提出的全局码书设计方案可以根据帧间相关性及码字使用频率,对码书的内容自动进行更新和替换,以适应场景内容的变化。实验结果表明：在保证图像重建质量的前提下,本文提出的方法具有较高的压缩效率,比较适合于视频会议以及水下视频观测等应用场合。     

一种高效的基于矢量量化的彩色视频图像压缩编码方法

针对彩色视频图像提出了一种DCT域内基于矢量量化的高效编码方法.为去掉彩色图像各分量间的相关性,首先将图像由RGB空间转换到YUV空间,然后根据人类视觉特征(HVS)对色度信号U、V进行了亚采样和平均化处理;对亮度信号Y则进行分块DCT变换,并根据HVS特征对变化域内的块矢量进行自适应分类,然后根据矢量的类型分别构造码矢和进行全局码书设计.提出的全局码书设计方案可以根据帧间相关性及码字使用频率,对码书的内容自动进行更新和替换,以适应场景内容的变化.实验结果表明:在保证图像重建质量的前提下,本文提出的方法具有较高的压缩效率,比较适合于视频会议以及水下视频观测等应用场合.     

基于组合混沌系统的彩色视频流加密算法

为进一步加强视频图像在存储及传输过程中的安全性,提出一种将两种改进的混沌系统和分组加密算法结合的彩色视频流加密方案.将原视频逐帧提取并取其RGB分量,并用改进的logistic混沌系统控制其高低位进行各分量位重组.再利用级联式二维猫映射,对亮度分量R实现快速空域置乱;通过改进型二维logistic映射构造的非线性混沌序列,对色度分量GB分量进行迭代扩散.然后将已加密的三分量通过AES算法进行二重加密.算法利用了高低维混沌的空域混合双重加密.仿真结果表明该算法的解密图像无损、无失真,具有更好的密钥敏感性、更好的安全性.     

色度与亮度特征相融合的彩色人脸识别算法

在存在色度与亮度差异性的条件下,彩色人脸的识别准确度不高,为了提高彩色人脸的识别性能,提出基于色度与亮度特征相融合的彩色人脸识别算法。对采集的原始彩色人脸图像进行色度均衡处理,采用特征提取方法进行人脸的关键特征点定位,提取人脸图像的色度和亮度特征。对提取的特征量根据眼睛和眉毛等关键点的差异性进行信息融合,对提取的眼部区域色度信息进行二值化分离和信息增强处理,提高对彩色人脸图像的特征识别能力,实现彩色人脸识别算法的改进设计。仿真结果表明,采用该方法进行彩色人脸识别的准确识别率较高,抗色度和亮度的局部干扰能力较强。     

Motion Compensated Component Color Coding

We develop and evaluate motion compensation schemes for predictive coding of the component color television signal. Algorithms are discussed for estimation of motion of each color component (luminance and chrominance) separately as well as in combination. Techniques for switching of the predictors for individual components are proposed and simulated. Simulations show that it is sufficient to estimate parameters of motion based only on the luminance and use them for motion-based prediction and switching the predictors for both the luminance and chrominance. Thus, only one motion estimator and prediction switch is needed for the three components of the color signal. Compression capability of motion compensation is scene dependent, in some video conference type of scenes, bit rate is reduced by as much as 60 percent compared to conditional replenishment coding.     

WHT-based composite motion compensated NTSC interframe directcoding

The motion compensated interframe differential pulse code modulation (DPCM) and discrete cosine transform (DCT) hybrid (MC DCT) coding was nominated as a standard scheme for component TV signals by ISO and ITU-R. However, in cases where an NTSC composite TV signal is used such as the United States and Japan, applying the MC DCT scheme with its luminance/chrominance separating and composing process causes unavoidable quality degradation. The reason for this additional process required for MC DCT is that a composite TV signal presents a “color subcarrier phase shift problem” in which the color subcarrier phase varies between a coding block and reference block according to the motion vector. In this paper, we propose a Walsh Hadamard transform (WHT)-based composite motion compensated NTSC interframe direct coding scheme. In this scheme, phase shifts of a color subcarrier and modulated chrominance components between a coding block and reference block can be effectively compensated by a simple process of coefficient permutation and polarity changes of several pairs of WHT coefficients to which 100% of the subcarrier energy and most of the modulated chrominance component's energy are packed. In the motion compensated DCT scheme, however, the energy of the color subcarrier and modulated chrominance components are spread over too many coefficients and a pair-based coefficient handling rule is not given to solve this problem. This paper demonstrates that the proposed scheme provides higher coding performance for a composite NTSC signal than does the motion compensated DCT scheme with its luminance/chrominance separating and composing process     

针对对比度变化的图像质量评价方法

由于对比度变化容易引入图像亮度和色彩等失真,本文提出了一种面向对比度变化的图像质量评价方法CCIQA。所提方法先将图像进行亮度和色度分离,再分别根据亮度强度变化和明暗对比度变化提取亮度失真因子和根据色度相似性提取色度失真因子,接着依照基于亮度强度的权重图进行融合并计算得到最终图像质量评价分数。所提CCIQA方法在4个常用的数据库,TID2008,TID2013,CID2013和CCID2014进行广泛测试。实验结果表明所提CCIQA算法符合人眼视觉对对比度变化的主观感知,且算法性能优于多个最新图像质量评价方法。      

HDTV信号的自适应亚取样压缩编码

本文提出了一种280Mb/s码率的HDTV压缩编码方案。亮度分量采用1/4亚取样配合自适应细节补传,色度分量采用1/2亚取样及R-Y/B-Y行轮换传送。在解码端,亮、色分量均采用2D内插重建复原,本方案的特点是抗误码能力强、算法简单、易于实现。实验获得了优良的重建图像质量。     

Color contrast enhancement method using steerable pyramid transform

A new method of contrast enhancement based on steerable pyramid transform is presented in this work. The use of steerable filters is motivated by the fact that the images are to be observed by human and therefore it would be better to incorporate some knowledge on the Human Visual System in the design of the image processing tool. Here, the frequency and directional selectivity of the HVS is modeled by the steerable filters. The contrast is amplified using a selective nonlinear function which simulates the nonlinearity response of the HVS to the luminance stimuli. So the basic idea is to enhance the luminance signal irrespective of the two chrominance components using a multidirectional and multiscale decorrelation color transform. Initially the rgb (red, green and blue) color image is converted to lab (luminance and chrominance) color image. Only the luminance component is transformed by the steerable pyramid transform, so that the luminance component is independently decomposed into different scale and orientation sub-bands. The contrast in each sub-band is enhanced using a nonlinear mapping function. Finally the rgb color image is obtained from the enhanced luminance component along with the original chrominance components. The performance of the proposed method is objectively evaluated using spectrum energy analysis and a visibility map based on a perceptual filtering model. The obtained results confirm the efficiency of the method in enhancing subtle details without affecting color balance and without the usual noise amplification and edge ringing effect.     

Supervised‐learning‐based algorithm for color image compression

A correlation exists between luminance samples and chrominance samples of a color image. It is beneficial to exploit such interchannel redundancy for color image compression. We propose an algorithm that predicts chrominance components Cb and Cr from the luminance component Y. The prediction model is trained by supervised learning with Laplacian‐regularized least squares to minimize the total prediction error. Kernel principal component analysis mapping, which reduces computational complexity, is implemented on the same point set at both the encoder and decoder to ensure that predictions are identical at both the ends without signaling extra location information. In addition, chrominance subsampling and entropy coding for model parameters are adopted to further reduce the bit rate. Finally, luminance information and model parameters are stored for image reconstruction. Experimental results show the performance superiority of the proposed algorithm over its predecessor and JPEG, and even over JPEG‐XR. The compensation version with the chrominance difference of the proposed algorithm performs close to and even better than JPEG2000 in some cases.     

Effects of Digital Demodulation on Component Coding of NTSC Color Signals

Effects of nonideal filtering in the digital demodulation of the composite NTSC signal into luminance and chrominance components on the coding of the luminance component are discussed. The residual chrominance component is shown to cause degradation in prediction and/or motion detection algorithms which are based on line or frame difference signals. Simple techniques for reducing these effects using chrominance-band rejection filters are presented and the efficacy of these methods are verified by simulation.     

基于亮度反馈的彩色雾霾图像增强算法

针对目前主流去除雾霾算法采用亮度和色度分量分而治之的机制,割裂了二者固有的相关性,致使增强后图像质量不能两者兼顾的问题,本文以人眼视觉特性为依据,提出了一种亮度反馈的增强方法.该方法首先对亮度信息进行区域适应性调整,并对其细节和边缘进行提升,然后将该结果纳入色度信息处理的约束条件,较好的保持了两者间的相关性.实验表明本文算法在去除雾霾后视觉效果优异,具有较好的实用性和较少的计算资源消耗.     

3D Color Set Partitioning in Hierarchical Trees

This paper introduces the 3D color set partitioning in hierarchical trees (3D-CSPIHT) low bit rate embedded video coding scheme. The codec exploits the correlation between temporal and spatial wavelet coefficients and the interdependency between luminance and chrominance components to code color video sequences without the need for explicit bit allocation. Besides offering rate scalability, the new codec also produces multi-resolution scalable code streams. The hierarchical variable size block matching motion estimation technique is also integrated to demonstrate the motion estimation option with 3D-CSPIHT. The coding results show that 3D-CSPIHT produces better performance and visual quality compared to 3D-SPIHT.     

Wavelet-based watermarking for color images through visual masking

In this paper, a wavelet-based watermarking scheme for color images is proposed. The watermarking scheme is based on the design of a color visual model that is the modification of a perceptual model used in the image coding of gray scale images. The model is to estimate the noise detection threshold of each wavelet coefficient in luminance and chrominance components of color images in order to satisfy transparency and robustness required by the color image watermarking technique. The noise detection thresholds of coefficients in each color component are derived in a locally adaptive fashion based on the wavelet decomposition, by which perceptually significant coefficients are selected and a perceptually lossless quantization matrix is constructed for embedding watermarks. Performance in terms of robustness and transparency is obtained by embedding the maximum strength watermark while maintaining the perceptually lossless quality of the watermarked color image. Simulation results show that the proposed scheme is more robust than the existing scheme while retaining the watermark transparency.