Kohei Cho

An evaluation of JPEG compression for on-line satellite images transmission

Image compression is a key technology to realize on-line satellite image transmission economically and quickly. Among various image compression algorithms, the JPEG algorithm is the international standard for still color image compression. In this study, various kinds of satellite images were compressed with the JPEG algorithm. The relation between compression ratio and image quality were evaluated. As for the image quality evaluation, both subjective evaluation and objective evaluation were performed. It was determined that all the test satellite images could be compressed to at least 1/10 of the original data volume preserving high visual image quality. The degradation of spatial distribution quality of the compressed images were evaluated using power spectrum of original and compressed images.<<ETX>>

Preparation of multi-stage remote sensing for monitoring sea ice in the Okhotsk Sea with ALOS sensors

In order to develop and/or improve algorithms of extracting various sea ice parameters, such as sea ice concentration, sea ice thickness, and sea ice types from ALOS data, it is necessary to prepare certain data set for verification. This paper describes about the preparation of multi-stage remote sensing for obtaining a series of remotely sensed data of sea ice in the Okhotsk Sea.

Validation of SSM/I sea ice concentration algorithms for the Okhotsk Sea

Satellite passive microwave radiometers, such as SSM/I, can observe sea ice distribution at global scale. Two sea ice concentration algorithms, namely the NASA Team algorithm and the Bootstrap algorithm were compared for the Okhotsk Sea. Though the correlation coefficient of the two ice concentrations were 0.97, the Bootstrap ice concentrations were mostly higher than the NASA Team ice concentrations. In some seasons, the ice concentrations of a particular sea ice area appeared to be much higher for the Bootstrap compared with the NASA Team algorithm. The difference suggested the sea ice condition difference of the area. The reduction of weather/land effects by both algorithms were not as much as expected. The land filter developed by the authors could effectively reduce the land effect.

Study on glacier movement using satellite SAR and visible/near-IR imagery

The movement of Shirase glacier and Kaya glacier in Lutzow-Holm Bay in Antarctica was analyzed using LANDSAT/TM, MSS, MOS-1/MESSR and ERS-1/SAR data. Through multi-temporal analysis, the velocity of the Shirase glacier floating ice tongue was estimated to be 2.9 km/year for 1988-1989 and 2.6 km/year for 1989-1991. ERS-1/SAR image was compared with MOS-1/MESSR near-in image for Kaya glacier and sea ice. Floating ice tongue edges and fast ice in both images show clear differences, which suggests the importance of multi sensor analysis for glacier study.<<ETX>>