40 
Development of Color of Sea Database to Estimate 
Transparency with Landsat TM 
Katsutoshi Kozai 
Kobe Univ. Mercantile Marine 
Faculty of Ocean Mechanical Engineering 
5-1-1, Fukaeminami, Higashinada, Kobe 658 Japan 
Tel:+81-78-431-6276, Fax: +81-78-431-6365 
E-mail: kouzai@kumm.cc.kshosen.ac.jp 
Abstract 
Based on the color of sea data measured with JIS(CIE) color standard by Osaka 
prefectural fisheries experiment station, a chromaticity database is developed with transparency 
in Osaka Bay. An empirical model is derived from the database to explain the relationship 
between the transparency and the main wavelength which is one of the parameters describing the 
distribution of chromaticity. The main wavelength calculated from Landsat TM is used to 
estimate transparency for the entire Osaka Bay. The results of verification shows the rms error 
of 67cm of transparency between the estimated and the observed and indicates that the color of 
sea database approach to estimate transparency is promising in obtaining not only vertical but 
also horizontal optical variabilities of Osaka Bay water. 
1. Introduction 
Osaka prefectural fisheries experiment station has measured color of sea in Osaka Bay by 
using Forel-Ure standard since 1950’s. However, they changed the method of observation from 
the Forel-Ure to the JIS(CIE) color standard in 1971 because of inadequate representation of 
Forel-Ure measurement for the in situ color of sea (l) . Both observation methods are so called 
visual comparisons, but the Forel-Ure method specifies only one number of standard color close 
to the in situ color, while the JIS color standard method specifies 3 parameters, such as hue, 
value and chroma which are said to be close to the perception of human eyes (2) . This study 
develops a color of sea database of Osaka Bay based on the JIS color standard and aims at 
estimating transparency of Osaka Bay with integrated use of Landsat TM and the database- 
derived empirical model explaining the relationship between transparency and the main 
wavelength. Moreover since the color of sea database developed here is spectrally continuous, 
the method should be ready for coming hyperspectral images such as EOS MODIS (3) .