Souichi Kubo

A New Spectrophotometer for Measuring the Spectral Reflectance of Gastric Mucous Membrane

AbstractA new spectrophotometer has been developed for measuring the spectral reflectance of the gastric mucous membrane. This spectrophotometer comprises an endoscope, spectrophotometer, optical multichannel analyzer, silicon photodiode linear image sensor with 1024 channels, and a microcomputer. With this equipment, it is possible to measure the spectral reflectance of gastric mucous membrane from 350 nm to 830 nm at 5-nm intervals, instantaneously.In this paper, the spectrophotometer is described, the accuracy is analyzed, and the results of spectral reflectance measurements of gastric mucous membrane for 26 patients are presented.

Spatial Frequency Channels fOr StereOSCOpic Depth Perception

We investigated spatial frequency tuning of the mechanisms for stereoscopic depth perception, using a masking technique, and compared these tunings with those for luminance pattern detection. Observers discriminated depth direction in random-dot stereograms with various contrasts of a masking pattern, which was dichoptic stimulus of uncorrelated random dots. The strength of masking effect as a function of spatial frequency (i.e., masking function) was measured: masking function approximates the spatial frequency tuning of the mechanism that detects the depth in the test pattern. The masking functions for stereoscopic depth were found to be similar to either of the three of the six spatial frequency channels proposed by Wilson and Gelb (1984) for the detection of luminance patterns.

Relationship Between Human Evaluation Of The Sharpness Of An Image And Modulation Transfer Function

The paper examines the relationship between human evaluation of the sharpness of an image and the objective degree of edge enhancement, defined in terms of a modulation transfer function derived from a physical light source and photographic materials. Human perception of the sharpness of the image was measured by the modified method of constant stimuli. The sharpness of the images of four pictures was correlated with the modulation transfer function expressed by information volume and photographic materials. The sample correlation coefficient was r = 0.83. Theoretical implications of less than perfect correlation between the human evaluation and physical units are thoroughly discussed.

Liquid-Crystal Containing Light Sensitive Microcapsules

This paper describes an experimental method of making cholesteric liquid-crystal containing microcapsules of complex hydrophilic colloid materials as well as a photographic application. The purpose of this study is to obtain a colored photographic image whose tonal characteristics are a function of temperature.