Article ID: 2018-049
Combination of three visible bands of the Advanced Himawari Imager (AHI) on-board JMA's new-generation Himawari-8 and -9 geostationary meteorological satellites enable production of true color imagery. True color is intuitively understandable to human analysts and beneficial for monitoring surface and atmospheric features. It is especially useful when applied to frequent observation from a geostationary platform. This article reports on an application of a color reproduction approach based on the CIE 1931 XYZ color system to imagery rendering. The approach allows consideration of primary color (RGB) differences among satellite and output devices which in turn cause differences in the colors reproduced. The RGB signals observed by AHI are converted to XYZ tristimulus values, which are independent of devices themselves, and then re-converted to RGB signals for output devices via the application of 3 x 3 conversion matrices. The article also covers an objective technique for the evaluation of XYZ values accuracy. The evaluation indicated that the combination of AHI native RGB bands is sub-optimal for obtaining XYZ values as-is, while a combination in which the green band is replaced by a pseudo band with a central wavelength of around 0.555 µm is optimal. The pseudo band is generated via regression with existing visible and near-infrared bands as predictor variables. The imagery produced using this approach was termed True Color Reproduction (TCR). The approach is applicable to other satellites that have several bands in the visible to near-infrared spectral range, and has the potential for development toward the production of standardized sensor-independent true color imagery.