Painting-like Image Emphasis based on Human Vision Systems

Regional image emphasis is often evident in paintings and illustrations. This technique increases local contrast while reducing global contrast by amplifying image intensity on shadowed surfaces, reducing intensity on illuminated surfaces, and then expanding contrast at intensity edges. The effects are assumed to result from the visual processing needed to interpolate the real world onto canvas. Therefore, we propose an intensity emphasis method based on human vision. This method simulates the adaptation of photoreceptor cells and the lateral inhibition of receptive fields. These attributes of a vision system are realized by computation of relative intensity and differential intensity in small areas. The proposed method can successfully generate painting-like artifacts, which greatly improves the perception of visual elements displayed in an image. Since the method efficiently reduces the dynamic range of images, it can be used for displaying highlighted images on standard graphic monitors. Experiments on a computer-generated image and a photograph confirm the advantages of our method.     

基于人眼视觉感知的场景明暗适应动态过程模拟

针对现有计算机真实感图形学及虚拟现实主流显示算法不能表现当环境光强骤变时人眼对场景感知变化的缺陷,提出并实现了一个基于人眼感光细胞亮度响应机制的明暗适应过程模拟的增强显示新算法.该算法首先针对人眼中视锥细胞和视杆细胞不同的生理反映机制,利用了双边滤波方法建立起感光细胞接受光刺激后同周边细胞之间的作用关系模型,然后在不同亮度环境下建立起亮度随时间响应的变化模型.结合图像高动态范围图像的色调映射处理模型及实验心理学中的经验模型,并经实验调整不同环境亮度下的生理适应值,通过逆响应变换及颜色适应变换,最终在三维场景中较为逼真地模拟出人眼在明暗适应过程中的对场景的动态感知变化.     

A modified Multi Scale Retinex algorithm with an improved global impressionof brightness for wide dynamic range pictures

This paper presents a new method of compressing the dynamic range of wide dynamic range scenes. This method is based on the Multi Scale Retinex algorithm. It improves the results of the original Multi Scale Retinex algorithm in a way that retains the global brightness contrast and the natural impression of the resulting image by recombining the original picture in a certain weight. Further improvement of the global brightness contrast is achieved by adjusting the histogram of the resulting picture. The paper explores the performance of this modified algorithm on different wide dynamic range scenes and points out its advantages over other dynamic range compression algorithms.Received: 7 November 2002, Accepted: 1 December 2003, Published online: 17 August 2004 Correspondence to: Orly Yadid-Pecht     

在可编程图形硬件上实现图像高动态范围压缩

通过在亮度图像梯度域上对大梯度进行衰减,压缩图像亮度的动态范围,可以使高动态范围图像在被显示时,既能够适应常规的显示硬件,同时又充分保留原始图像的细节信息,使得图像在被观察时能够重现真实场景的亮度效果。文中采用适合由图形处理器加速的快速算法,将整个处理过程通过可编程图形硬件实现,建立快速的图像动态范围压缩技术,建立起适用于高动态范围图像显示的实时应用框架,使之不仅适用于基于图像的动态范围调整的绝大部分情况,还能够成为各种交互式图形应用的核心技术之一。     

VB6.0图象动态显示技术及实现

图象动态显示的基本思想是从源图象向目标图象复制象素 块,即把一个图象框控件上的象素块移动到另一个图象框控件上。介绍了图象形式、图象文 件格式、图象动态显示编程技术,应用VB6.0实现扫描、百叶窗、马赛克等的动态显示,并 给出了其程序的主要代码。     

宽动态范围图像快速增强算法

提出了一种针对宽动态范围图像的快速增强算法。该算法基于反转后宽动态范围图像与雾天图像有相似特性的结论,对宽动态范围图像进行反转处理,将优化后基于暗原色先验理论的去雾算法用于反转后的图像。通过改进透射率估计方法和简化大气光估计,显著地降低了算法的复杂度。实验结果表明,该算法有效地改善了宽动态范围图像的视觉效果,并且算法的处理速度很快,能够满足实时应用的要求。     

利用VB、Delphi轻松实现图象漫游

分析了为解决如何在自己的程序中实现图象漫游技术的两个方案 ,指出了各自的优缺点 ,总结出利用VB、Delphi等 RAD实现图象漫游的便捷方法 ,可产生出类似于著名看图软件 ACDSee32中拖动图象和随鼠标即指即移等两种漫游效果 ,给出了编程步骤和代码。     

一种扩展动态范围的图像处理算法

为抑制强背景光而获取目标图像,扩展图像传感器的动态范围是一种有效的方法.图像传感器动态范围的扩展可采用多种技术,如对数像素结构、横向溢出栅像素机构、多次曝光技术、局部曝光技术等.提出一种图像处理的算法来扩展动态范围,其原理是对同一图像进行连续采集两次,利用数学算法对图像进行合成以达到动态外围的扩展,进而提高图像的信噪比...     

用强度系列成象法获取或显示高动态范围图象

提出一种适合于高动态范围图象的获取和显示的强度系列成象法。改变输入图象的强度，微机控制的图象采集系统进行记录得到一组磁盘文件，形成强度图象系列。基于记录的系列图象，可以进行信息提取、变换和显示等操作。基于获得的图象系列，提出一种剪贴操作进行快速的非线性图象变换。给出对光学功率谱处理的一个实例，它相当于进行锯齿形的非线性变换。     

Recognition and localization of objects with curved surfaces

This paper concerns the problem of recognition and localization of three-dimensional objects from range data. Most of the previous approaches suffered from one or both of the following shortcomings: (1) They dealt with single object scenes and/or (2) they dealt with polyhedral objects or objects that were approximated as polyhedra. The work in this paper addresses both of these shortcomings. The input scenes are allowed to contain multiple objects with partial occlusion. The objects are not restricted to polyhedra but are allowed to have a piecewise combination of curved surfaces, namely, spherical, cylindrical, and conical surfaces. This restriction on the types of curved surfaces is not unreasonable since most objects encountered in an industrial environment can be thus modeled. This paper shows how the qualitative classification of the surfaces based on the signs of the mean and Gaussian curvature can be used to come up withdihedral feature junctions as features to be used for recognition and localization. Dihedral feature junctions are robust to occlusion, offer a viewpoint independent modeling technique for the object models, do not require elaborate segmentation, and the feature extraction process is amenable to parallelism. Hough clustering on account of its ease of parallelization is chosen as the constraint propagation/ satisfaction mechanisms. Experimental results are presented using the Connection Machine. The fine-grained architecture of the Connection Machine is shown to be well suited for the recognition/localization technique presented in this paper.     

车辆牌照识别系统的一个新的实现方法

提出了一种新的车牌识别系统的实现方法，使得在各种不同的光照条件下，通过使用一个具有较大的动态变化范围的传感系统来获取更精确的车牌图像，这个传感系统是通过对两个不同的曝光条件下的图像进行合成，进而来扩展其动态变化范围的。为了避免快速行驶车辆所造成的图像模糊，安装了一个相当于多层过滤器的棱形电子束分裂器，通过调整其入射光与透射光的强度比率来实现图像获取，实验结果表明，提出的这种系统对于车牌识别是很有效的。     

改进的多尺度Retinex图像增强算法

针对多尺度Retinex算法在图像增强的过程中,存在着算法运算量大的问题,提出了一种基于快速二维卷积和多尺度连续估计的算法。该算法充分利用二维图像高斯卷积的可分离性和多尺度照射光连续估计的可行性,降低了Retinex算法的复杂度。同时对于增强后图像色彩容易失真的现象,提出了一种去极值的直方图裁剪法,用于保持图像色彩信息和提高对比度。实验结果表明,这些改进可以有效提高算法运行速度和改善图像增强效果。     

基于视觉信息保真度的图像增强质量客观评价方法

视觉信息保真度(VIF)是一种基于自然场景统计模型(NSS)、图像失真和人类视觉失真建模的新判据。传统上,图像质量评价算法将图像质量解释为使用"基准"或"完美"的图像作为参考的相似性或者保真度。本文将VIF方法应用于图像增强效果的评价,该方法将失真图像取代"完美"图像作为参考图像以评价增强后的图像的质量。由于VIF指标在某种程度上融合了HVS的特点,因此,相比传统方法具有明显的优势。本文通过大量的主观测试对该方法进行验证,实验显示该方法的性能优于当前的其他方法。     

交会对接航天员训练电视图像实时高动态范围渲染

应用基于人眼视觉系统的高动态范围实时渲染技术处理交会对接仿真场景,可以为航天员手控交会对接训练提供高逼真度的电视图像.文中结合交会对接电视图像的特点,分析了交会对接航天员训练电视图像高动态范围实时渲染的关键技术;根据两航天器相对距离,将交会对接过程分为远、中和近3个距离段,采用S-curve算法、自适应对数算法和Reinhard算法分别对每个距离段进行调和映射处理;改进了自适应对数算法和Reinhard算法,并基于GPU处理技术实现仿真电视图像的实时显示.实验结果表明,采用基于距离变化调整调和映射算法的方法处理交会对接仿真电视图像可以高逼真地模拟实录视频场景,为航天员手控交会对接训练提供了视景支持.     

Story Albums: Creating Fictional Stories From Personal Photograph Sets

We present a method for the automatic creation of fictional storybooks based on personal photographs. Unlike previous attempts that summarize such collections by picking salient or diverse photos, or creating personal literal narratives, we focus on the creation of fictional stories. This provides new value to users, as well as an engaging way for people (especially children) to experience their own photographs. We use a graph model to represent an artist‐generated story, where each node is a ‘frame’, akin to frames in comics or storyboards. A node is described by story elements, comprising actors, location, supporting objects and time. The edges in the graph encode connections between these elements and provide the discourse of the story. Based on this construction, we develop a constraint satisfaction algorithm for one‐to‐one assignment of nodes to photographs. Once each node is assigned to a photograph, a visual depiction of the story can be generated in different styles using various templates. We show results of several fictional visual stories created from different personal photo sets and in different styles.     

同一场景不同曝光图像的配准及HDR图像合成

提出了一种针对同一场景不同曝光的多幅照片图像的配准、恢复光照响应曲线及高动态范围图像合成算法.首先将不同曝光的序列图像中值二值化,利用多尺度思想构造二值图像的金字塔序列并逐级比较,以实现多幅图像间的平移配准和转角配准.从配准后的序列图像中采样,根据最小二乘原理拟合出相机的光照响应曲线,并获得图像中像素值与曝光量之间的映射关系,进而将不同曝光的场景照片图像融合成一幅高动态范围图像.实验结果表明,合成的高动态范围图像效果满意.     

求解低秩矩阵融合高动态范围图像

目的 利用低秩矩阵恢复方法可从稀疏噪声污染的数据矩阵中提取出对齐且线性相关低秩图像的优点,提出一种新的基于低秩矩阵恢复理论的多曝光高动态范围（HDR）图像融合的方法,以提高HDR图像融合技术的抗噪声与去伪影的性能。方法 以部分奇异值（PSSV）作为优化目标函数,可构建通用的多曝光低动态范围（LDR）图像序列的HDR图像融合低秩数学模型。然后利用精确增广拉格朗日乘子法,求解输入的多曝光LDR图像序列的低秩矩阵,并借助交替方向乘子法对求解算法进行优化,对不同的奇异值设置自适应的惩罚因子,使得最优解尽量集中在最大奇异值的空间,从而得到对齐无噪声的场景完整光照信息,即HDR图像。结果 本文求解方法具有较好的收敛性,抗噪性能优于鲁棒主成分分析（RPCA）与PSSV方法,且能适用于多曝光LDR图像数据集较少的场合。通过对经典的Memorial Church与Arch多曝光LDR图像序列的HDR图像融合仿真结果表明,本文方法对噪声与伪影的抑制效果较为明显,图像细节丰富,基于感知一致性（PU）映射的峰值信噪比（PSNR）与结构相似度（SSIM）指标均优于对比方法：对于无噪声的Memorial Church图像序列,RPCA方法的PSNR、SSIM值分别为28.117 dB与0.935,而PSSV方法的分别为30.557 dB与0.959,本文方法的分别为32.550 dB与0.968。当为该图像序列添加均匀噪声后,RPCA方法的PSNR、SSIM值为28.115 dB与0.935,而PSSV方法的分别为30.579 dB与0.959,本文方法的为32.562 dB与0.967。结论 本文方法将多曝光HDR图像融合问题与低秩最优化理论结合,不仅可以在较少的数据量情况下以较低重构误差获取到HDR图像,还能有效去除动态场景伪影与噪声的干扰,提高融合图像的质量,具有更好的鲁棒性,适用于需要记录场景真实光线变化的场合。     

A Variational Framework for Retinex

Retinex theory addresses the problem of separating the illumination from the reflectance in a given image and thereby compensating for non-uniform lighting. This is in general an ill-posed problem. In this paper we propose a variational model for the Retinex problem that unifies previous methods. Similar to previous algorithms, it assumes spatial smoothness of the illumination field. In addition, knowledge of the limited dynamic range of the reflectance is used as a constraint in the recovery process. A penalty term is also included, exploiting a-priori knowledge of the nature of the reflectance image. The proposed formulation adopts a Bayesian view point of the estimation problem, which leads to an algebraic regularization term, that contributes to better conditioning of the reconstruction problem.Based on the proposed variational model, we show that the illumination estimation problem can be formulated as a Quadratic Programming optimization problem. An efficient multi-resolution algorithm is proposed. It exploits the spatial correlation in the reflectance and illumination images. Applications of the algorithm to various color images yield promising results.     

Dynamic Fractal Transform with Applications to Image Data Compression

A recent trend in computer graphics and image processing is to use Iterated Function System(IFS)to generate and describe both man-made graphics and natural images.Jacquin was the first to propose a fully automation gray scale image compression algorithm which is referred to as a typical static fractal transform based algorithm in this paper.By using this algorithm,an image can be condensely described as a fractal transform operator which is the combination of a set of reactal mappings.When the fractal transform operator is iteratedly applied to any initial image,a unique attractro(reconstructed image)can be achieved.In this paper,a dynamic fractal transform is presented which is a modification of the static transform.Instea of being fixed,the dynamic transform operator varies in each decoder iteration,thus differs from static transform operators.The new transform has advantages in improving coding efficiency and shows better convergence for the deocder.