We developed a quantitative evaluation method for luminance and color uniformity on a display screen. In this paper, we report the analysis result of a viewer perception of luminance and color uniformity. In experiments, observers subjectively evaluated Mura images which were showed on the light emitting diode (LED) backlight screen by adjusting the luminance of each LED. We measured the luminance and color distributions of the Mura images by a 2D colorimeter, then, the measured data was converted into S-CIELAB. In S-CIELAB calculations, two dimensional MTF (Modulation Transfer Function) of human eye were used in which anisotropic properties of the spatial frequency response of human vision were considered. Some indexes for a quantitative evaluation model were extracted by the image processing. The significant indexes were determined by the multiple regression analysis to quantify the degree of uniformity of the backlight screen. The luminance uniformity evaluation model and color uniformity evaluation model were derived from this analysis independently. In addition, by integrating both of these models we derived a quantitative evaluation model for luminance and color unevenness simultaneously existing on the screen.

Overall picture quality of a liquid crystal display (LCD) is changed by viewing conditions. An evaluation method of overall picture quality was proposed for LCDs. However, the estimation values calculated by the evaluation method differed from the subjective evaluation values, when viewing angle changed in the vertical direction. In this study, the coefficients of impairment in the evaluation equation were obtained by the multiple regression analysis using subjectively evaluated data. The evaluation method of overall picture quality was improved by weighting factors using these coefficients. As the result, the good estimation accuracy was obtained even if the viewing angle was changed both in the horizontal and vertical directions individually.

This paper proposes the evaluation methods for measuring retrieval effectiveness of Web search engine systems, attempting to make them suitable for real Web environment. With this objective, we constructed 100-gigabyte and 10-gigabyte document sets that were mainly gathered from the '.jp' domain, and conducted an evaluation workshop at the third NTCIR Workshop from 2001 to 2002, where we assessed the retrieval effectiveness of a certain number of Web search engine systems using the common data set. Conventional evaluation workshops assessed the relevance of the retrieved documents, which were submitted by the workshop participants, by considering the contents of individual pages. On the other hand, we assessed the relevance of the retrieved pages by considering the relationship between the pages referenced by hyperlinks.

This paper presents a new method to evaluate time stamping schemes from three viewpoints: integrity of a time stamp, cost of issuing and verifying a time stamp and availability of the schemes. The main advantage of the proposed evaluation method is to clarify whether or not a certain scheme is optimal under certain prioritized requirements. Therefore, the proposed method can help potential users of time stamping services select an appropriate one which meets their prioritized requirements. In this paper, we explain the basic idea of the evaluation method and show how to use it by applying it to seven existing schemes.

This paper proposes the Vector Evaluated GA-ICT (VEGA-ICT), a novel design method that employs the Genetic Algorithm (GA) to obtain the optimum antenna design. GA-ICT incorporates an arbitrary wire-grid model antenna to derive the optimum solution without any basic structure or limitation on the number of elements by merely optimizing an objective function. GA-ICT comprises the GA and an analysis method, the Improved Circuit Theory (ICT), with the following characteristics. (1) To achieve optimization of an arbitrary wire-grid model antenna without a basic antenna structure, the unknowns of the ICT are directly assigned to variables of the GA in the GA-ICT. (2) To achieve a variable number of elements, duplicate elements generated by using the same feasible region are deleted in the ICT. (3) To satisfy all complex design conditions, the GA-ICT generates an objective function using a weighting function generated based on electrical characteristics, antenna configuration, and size. (4) To overcome the difficulty of convergence caused by the nonlinearity of each term in the objective function, GA-ICT adopts a vector evaluation method. In this paper, the novel GA-ICT method is applied to downsize sector antennas. The calculation region in GA-ICT is reduced by adopting cylindrical coordinates and a periodic imaging structure. The GA-ICT achieves a 30% reduction in size compared to the previously reported small sector antenna, MS-MPYA, while retaining almost the same characteristics.