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A new color-difference formula based on uniform color-difference space presented. CIELAB color space that was revised seemed to create an equal color difference between the adjacent hue lines or chroma lines on the Munsell system. Weighting functions for a new chroma scale and new hue-difference scale adjust the distance in uniform space to the perceived color-difference magnitude of the Munsell system. We called this uniform space a uniform color-difference space. We determined the total color-difference between two color samples with the weighting factor corresponding to the location of the color samples in uniform color-difference space. The Relationships between the total color-difference used in the new formula and the perceived magnitude were performs analyzed through visual perception data sets. The new formula is better than CIELAB, CIE94, and CIEDE2000.

The present study describes the usefulness and importance of chromatic tone concept on object colors. It is clarified that the concept of a tone category consists of the same perceived lightness and the same degree of vividness of chromatic object colors in the tone irrespective of hue. Prediction equations are given to color attributes on perceived lightness and degree of vividness. They clearly show different functions on metric lightness and metric chroma on the two color attributes. It is also clarified that the theoretical opponent-colors system by the author (NT system) gives a basis for defining the tone concept, perceived lightness, and degree of vividness. The results of the present study are useful for understanding fundamental color notion “tone,” which is important both in the fields of colorimetry (fundamental color-perception study) and color design (practical application). In addition, attributes of equivalent whiteness–blackness [W-Bk]eq and equivalent chroma Ceq are proposed. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 221–234, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20108

In this article, we provide colorimetry data for which it was judged that the colors between different media matched under various viewing conditions. Painted color patches, a monitor, and printed color patches were used in the color matching experiments, in which we compared the appearances of the painted color patch and the monitor, or the monitor and the printed color patch, using the method of constant stimuli. The nine types of viewing conditions we used could be envisaged to occur when comparing different device outputs indoors. The experimental data obtained were compared with corresponding colors predicted with the use of five types of color appearance model, including color appearance formulae. We found that when the view- ing conditions were the same for the different media, there was good agreement between the experimental data and the CIECAT94 model. And by adjusting the brightness induc- tion and the chromatic induction factors, it was possible to improve conformity for the lightness and the chromaticity. Moreover, it was possible to improve the white point shift, which cannot be adjusted with the use of optimized param- eters by introducing incomplete adaptation. By optimizing the parameters and introducing incomplete adaptation, it is possible to make the mean color difference E* ab between the corresponding color and the color matching point less than 10 CIELAB units for all of the viewing conditions. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 399 - 420, 2002; Pub- lished online in Wiley InterScience (www.interscience.wiley.com). DOI

The operating frequency of the inverter based on the resonant performance is fixed at the resonant frequency. Then, it is difficult to regulate the output voltage because the switch-on and -off time can not be set in an arbitrary manner. Therefore, the authors propose the control method of active use of the short-circuit mode to the voltage resonant type of push-pull high-frequency inverter circuit. The characteristics of the proposed inverter are carried out with analytical and experimental manner. The results of the theoretical steady-state analysis agree well with those in the experiment. The circuit efficiency is more than 90% in the wide control range.Further, the inverter is applied to the lighting circuit of electric-discharge lamp. In the lighting circuit made on an experimental basis, the wide range of output control from 83 V to 113 V of the supply voltage and the stable lighting of electric-discharge lamp can be achieved. Then, the circuit efficiency can be obtained over 88%.Thus, the proposed high-frequency inverter by using the short-circuit mode is proved to be of much practical use.