Influence of background and surround on image color matching

In this article, the corresponding‐color data for complex images reproduced on different media were obtained by simultaneous matching using an adjustment method. In our experiment printed color images and images displayed on a monitor were compared in different viewing conditions. The viewing condition varied in surround relative luminance and background. The experimental data show that surround relative luminance has little influence on color matching between printed and monitor images while changes in background modify color appearance. These results were used to evaluate different chromatic adaptation transforms (CAT). We found that for the same viewing conditions the SHARP transform shows the best agreement between the experimental and predicted data. SHARP transform can not predict accurately corresponding colors for blue and black regions. Therefore, we proposed new CAT that shows better characteristics than other transforms for cyan, green, and black colors and similar characteristics for other colors. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 244–251, 2007     

电压互感器二次侧三相电压不平衡现象的分析

从中性点不接地的电力系统中的绝缘监测功能单元及铁磁谐振角度出发,对安装消谐电阻器后引起电磁式电压互感器星三角接线二次侧三相电压不平衡现象进行了详细的分析和计算,得出了不平衡的一些原因及误差范围,并提出了改进措施,在实际使用中取得了较好的效果.     

Non‐Local Image Reconstruction for Efficient Computation of Synthetic Bidirectional Texture Functions

Visual prototyping of materials is relevant for many computer graphics applications. A large amount of modelling flexibility can be obtained by directly rendering micro‐geometry. While this is possible in principle, it is usually computationally expensive. Recently, bidirectional texture functions (BTFs) have become popular for efficient photorealistic rendering of surfaces. We propose an efficient system for the computation of synthetic BTFs using Monte Carlo path tracing of micro‐geometry. We observe that BTFs usually consist of many similar apparent bidirectional reflectance distribution functions. By exploiting structural similarity we can reduce rendering times by one order of magnitude. This is done in a process we call non‐local image reconstruction, which has been inspired by non‐local means filtering. Our results indicate that synthesizing BTFs is highly practical and may currently only take a few minutes for BTFs with 70 × 70 viewing and lighting directions and 128 × 128 pixels.     

Colour research with architectural relevance: How can different approaches gain from each other?

Colour research from different scientific traditions start from different basic questions and use different methods and concepts. This makes it difficult to communicate and to judge result relevance in a wider perspective. Here we start from architects' need of colour knowledge and discuss recent studies of colour appearance and colour emotion, with and without explicit connection to architecture. We stress the need for further development and clarification of concepts and conclude that the multitude of studies with different approaches can be seen as cases, jointly adding to a widened and deepened understanding of colour. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

Predictions of Munsell values with the same perceived lightness at any specified chroma irrespective of hues—Determination of any tonal colors

Simple formulas are proposed for predicting the Munsell value of colors with the same tone (the same values for whiteness‐blackness, perceived lightness, and chroma irrespective of hue). The formulas can be used for any tone. In other words, the method can determine the Munsell value with the same perceived lightness at any specified chroma irrespective of hue. The chromatic strength (CS) function is only used for the derivations. The formulas are very simple, and can be used not only in the colorimetry but also in the color design field. The concept described in this study is that a common CS function can be used for transforming each of the three color attributes (hue, lightness, and chroma) from their uniform color space metric to their corresponding color appearance space attribute. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011     

图像技术

本文概要地综述了国际照明委员会 (CIE)新近成立的第八分部 :图像技术 (Division 8　 ImageTechnology)的成立背景、任务及其技术委员会 (TC)的组成和职能。     

Glare‐limited appearances in HDR images

Abstract— Intraocular glare and simultaneous contrast control appearance in high‐dynamic‐range (HDR) images. This paper describes unique test targets that simulate real images. These targets change the HDR range by 500 times, without significantly changing the veiling glare on the retina. As well, these targets have nearly constant simultaneous contrast. The range of appearances possible from HDR images with different average luminances were measured. The targets displayed a maximum luminance range of 5.4 log units. Using magnitude estimates (MagEst) of appearances, the relationship between luminance and lightness from white to black was measured. With one exception, only small changes in appearance with large changes in dynamic range were found. It was also found that appearance was scene‐dependent. The same dark grays (MagEst = 10) were observed with luminances of 10, 4.2, 1.1, and 0.063, depending on the percentage of white area in the surround. Glare from more white increases the retinal luminance of the test areas. Simultaneous contrast counteracts glare by making the appearance range (white‐black) with a much smaller range of luminances. Appearance is controlled by both the optical scattered light and the spatial processing. A single tone‐scale function of luminance cannot describe appearance controlled by scatter and spatial processing.     

Froth-based modeling and control of flotation processes

This paper illustrates a new way for modeling and control of flotation processes based on froth appearances. As shown our previous work [Liu, J., MacGregor, J.F., Duchesne, C., Bartolacci, G., 2005. Monitoring of flotation processes using multiresolutional multivariate image analysis. Minerals Engineering 18 (1), 65–76], scores of the MR-MIA features can be viewed as numerical estimates of froth status or health. Therefore, scores of the MR-MIA features can be directly used in froth control as well as in froth modeling by employing the scores as process outputs (dependent variables).When applied to real froth images and corresponding process data, PLS regression provides good R² (the fraction of variance of dependent variables explained by the regression model) and Q² (the fraction of variance predicted for dependent variables not used in the regression model) values for both steady-state and dynamic causal models. Simulation study shows that a controller designed using the steady-state causal model provided control performances which were very satisfactory in achieving desired froth appearances.     

新筑灞河大桥检测评定及维修加固研究

在新筑灞河大桥的外观检测和静、动载试验的基础上,对此类旧桥承载能力评估及损伤诊断过程进行了具体分析和介绍,并对该桥的现状进行了综合评定,给出了维修加固建议,为日后管养工作提供了科学的依据。