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Image quality of halftone print is significantly influenced by optical characteristics of paper. Light scattering in paper produces optical dot gain, which has a significant influence on the tone and color reproductions of halftone print. The light scattering can be quantified by the Modulation Transfer Function (MTF) of paper. Several methods have been proposed to measure the MTF of paper. However, these methods have problems in efficiency or accuracy in the measurement. In this article, a new method is proposed to measure the MTF of paper efficiently and accurately, and the dot gain effect on halftone print is analyzed. The MTF is calculated from the ratio in spatial frequency domain between the responses of incident pencil light to paper and the perfect specular reflector. Since the spatial frequency characteristic of input pencil light can be obtained from the response of perfect specular reflector, it does not need to produce the input illuminant having “ideal” impulse characteristic. Our method is experimentally efficient since only two images need to be measured. Besides it can measure accurately since the data can be approximated by the conventional MTF model. Next, we predict the reflectance distribution of halftone print using the measured MTF in microscopy in order to analyze the dot gain effect since it can clearly be observed in halftone micro-structure. Finally, a simulation is carried out to remove the light scattering effect from the predicted image. Since the simulated image is not affected by the optical dot gain, it can be applied to analyze the real dot coverage. key words: MTF, paper, halftone print, dot gain

In recent years, many kinds of displays and recording systems for X-ray medical images have appeared. In this paper, sharpness of X-ray images displayed onto high-accuracy monochrome CRT and LCD monitors was analyzed and compared. Images recorded on the exclusive film and coated paper by inkjet printer and the wet-type and dry-type photo printers using a silver halide material were also analyzed and compared. The modified Gan's method was introduced to calculate the modulation transfer function (MTF) from the edge spread function (ESF). The results showed that the MTFs of the LCD, the inkjet image on the transparency, and the wet-type silver halide film image have fairly similar and good response in comparison with the inkjet image on the glossy paper and the dry-type silver halide film. It was also shown that the CRT has the worst response over the spatial frequency range. It was well correlated between the MTF and observer rating value. We thus consider the proposed method to be effective. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 90(11): 65–73, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20404

In this paper,we compared image qualities of movies displayed on an LCD (liquid crystal display) and a PDP (plasma display panel) by conducting a subjective experiment and measuring physical properties measurements of the displays.We prepared sixteen movies with different dynamic range,saturation,contrast and colorfulness,and 42 observers rated the quality of the movies.We also measured the displays' physical properties such as the luminance,chromaticity.We analyzed the relationship between the observers' ratings and the measured physical properties and found that the distribution of the luminance histogram is an important factor that affects the observers' reactions to the movies.

X-ray film systems have been widely used for a diagnosis of various diseases since a long time ago. In recent years, many kinds of displays and recording systems for X-ray medical images have been used including inkjet printer, silver halide film, CRT and LCD, by the development of the digital X-ray image capturing systems. In this paper, image quality of X-ray images displayed onto high accurate monochrome CRT and LCD monitors are analyzed and compared. Images recorded on the exclusive film and coated paper by inkjet printer and the wet type and dry type photo printers using a silver halide material are also analyzed and compared. The modified Gan's method is introduced to calculate the MTF (Modulation Transfer Function) from the knife ESF (edge spread function). The results show that the MTFs of the inkjet image on the transparency and the wet type silver halide film image have fairly similar and good response in comparison with the inkjet image on the coated paper and the dry type silver halide film. It is also shown that the CRT has the worse response over the spatial frequency range. It was well correlated between the MTF and observer rating value. From here, we consider the proposed method is effective.