True Color Imagery Rendering for Himawari-8 with a Color Reproduction Approach Based on the CIE XYZ Color System

Abstract

The combination of three visible bands of the Advanced Himawari Imager (AHI) aboard Japan Meteorological Agency's (JMA) new-generation Himawari-8 and Himawari-9 geostationary meteorological satellites enables the production of true color imagery. True color is intuitively understandable to human analysts and beneficial for monitoring surface and atmospheric features. It is particularly useful when applied to frequent observations from a geostationary platform. In this article, we report on an application of a color reproduction approach based on the International Commission on Illumination (CIE) 1931 XYZ color system to imagery rendering. This approach allows the 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 the AHI are converted to XYZ tristimulus values, which are independent of the devices themselves, and then reconverted to RGB signals for output devices via the application of 3 × 3 conversion matrices. This article also covers an objective technique for the evaluation of the accuracy of XYZ values. The evaluation indicated that the combination of AHI native RGB bands is suboptimal for obtaining XYZ values as is, whereas 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). This approach is applicable to other satellites that have several bands in the visible to near-infrared spectral range, and it has the potential for development toward the production of standardized sensor-independent true color imagery.

[Paper] Color Reproduction of Glass Dry Plate Scanned by a Linear Sensor Camera Using Filter Coefficient

“…In this study, we assume that output devices are compliant with sRGB 16) , which is generally used for many common electronic output devices. Then, to transform from XYZ to sRGB (with D 65 white point), the matrix transform is used as shown in Eq.…”

GeoColor: A Blending Technique for Satellite Imagery

“…radiometer systems have augmented environmental characterization capabilities dramatically. The newest generation of geostationary satellite imagers, represented by Japan's Himawari-8/9 Advanced Himawari Imager (AHI; Bessho et al 2016;Murata et al 2018), the U.S. Geostationary Operational Environmental Satellite (GOES)-R series Advanced Baseline Imager (ABI; Schmit et al 2017), and most recently Korea's Geostationary Korea Multi-Purpose Satellite 2A (GEO-KOMPSAT-2A) and its Advanced Meteorological Imager (AMI; Park et al 2016), offer 16 broad spectral bands spanning ;0.4-14 mm, with 0.5-2.0 km spatial resolution, temporal resolution as fine as 30 s (for mesoscale domains), and up to 14-bit radiometric pixel depth. The performance places these sensors on par with low-Earth-orbiting imagers, and offer a detailed and quantitative description of a wide array of surface and atmospheric parameters (Schmit et al 2017(Schmit et al , 2018.…”

The Wall: The Earth in True Natural Color from Real-Time Geostationary Satellite Imagery

“…Launched in 2016, and managed by NOAA, it has a resolution of 1 km at nadir but it lacks the visible green band. (3) The Himawari-8 [2,3] "Advanced Himawari Imager" (AHI) instrument managed by the Japan Meteorological Agency (JMA) was launched in 2014. This instrument captures all three visible bands with a resolution of 1 km at nadir and covers the Western Pacific region.…”

“…Today, several RGB composite terminologies are used: "Natural color RGB", "Natural color RGB (enhance)", "True color reproduction image", and "GeoColor", as displayed in Figure 1, all trying to mimic with more or less success what we think is "True natural color" corresponding to the human vision. Himawari-8 AHI uses the visible bands at 0.4697, 0.5094 and 0.6363 µm to directly build RGB images called "true color reproduction" images [3,5] (see inset (C) of Figure 1). Both Himawari-8 AHI and MSG2 SEVIRI create so-called "natural color RGB" composites [6] (see inset (A) of Figure 1) using the bands at 1.6, 0.8 and 0.6 µm, in which the clouds appear blue-green.…”