Falling attitude of snowflakes were simultaneously photographed by two tv camerae from horizontal and vertical directions. These images were analyzed by image processor and personal computer. The attitude and location of each snowflakes were measured every 1/30 seconds from their two images. There were two patterns in falling motion of snowflakes, one was rotational trajectory, the other was spiral trajectry. And there was a tendency that the rotational speed of smaller snowflakes was faster than the bigger one, and the directions of revolution and rotation in falling snowflakes were the same in many cases.

View full abstract

Variations in sea ice extent especially Antarctic sea ice condition have long been considered to influence global climate of the earth. Hence the investigation of the inter annual variations of Antarctic sea ice condition is important. A method to analyze the sea ice condition by image processing technique is proposed. The sea ice images were photographed by video camera on board the R/V "SHIRASE". The results of Antarctic ice concentration and floe size are also reported.

View full abstract

This paper investigates fingerprint image processing techniques to identify people accessing computer network systems. In the proposed fingerprint area detection scheme, the fingerprint image is divided into small blocks and each effective block is detected by using the average brightness of each binarized fingerprint image block. A thinned image template matching scheme is proposed. Subtemplate, multistage incremental values and discarding operations to reduce the matching time are shown. Parameters which affect matching error rates are discussed.

View full abstract

This paper presents the conversion of spatial and bit resolutions for multilevel images. The conversion is from the low spatial-high bit resolution image obtained by an image scanner to the high spatial-low bit resolution image displayed by a printer. The proposed method is based on the modelized impulse response of the scanner sensor to estimate the real edge route and then obtain new pixel values. Comparing the proposed method with two conventional ones, the reciprocal distance weight interpolation and the pixel replication, we obtain no error or much less error by the proposed one.

View full abstract

When the video coding algorithm is impiemented to the practical communication terminal, it is necessary to perform the coding control that is matched to this terminal characteriatics. This paper describes an experimental results of subjective quality evaluatuion on CRT and LCD, and discusses the difference of coding control methods between CRT and LCD.

View full abstract

Horizontal and vertical MTFs of CRT displays were measured under several television scanning systems. These systems are 1125/60/1 : 1 (Hi-Vision, or an interlace HDTV system), 1125/60/1 : 1 (the progressive scanning system of Hi-Vision). 1125/120/2 : 1,1125/120/4 : 2 and 2250/60/2 : 1. The latter four systems are the double rate scanning systems of Hi-Vision. The target CRTs are a 32 inches delta gun type and a 21 inches in-line gun type. As the results, vertical MTF was different by the number or scanning lines of the system in both CRTs. Horizontal MTF was different by the field frequency of the system only in the delta gun type.

View full abstract

This paper describes about a study of binocular fusion for the target size of random dot stereogram. As a result, a maximum disparity for binocular fusion increased as an enlargement of the target size, and the disparity showed a tendency of saturation or asymptotic increase at more than 30 or 40 degrees. Moreover, a maximum disparity in the case of changing both the component of spatial frequency and the target size was investigated, the value of disparity was a little difference at the small size target of involving any frequency components. But the maximum disparity for binocular fusion increased at the target of wide horizontal visual angle and involving high frequency components.

View full abstract