High Dynamic Range Image Rendering with a Luminance-Chromaticity Independent Model

High dynamic range image (HDR) is widely used since it is capable of capturing more fine information. However, problems remain in its display. A good rendering of HDR color images requires careful treatment of both the brightness and chromaticity information. In this work, we first prove that the global logarithmic mapping of the R, G, B channels may result in desaturation. We then propose an improved way for HDR image rendering. Specifically, by keeping the chromaticity fixated, we use a global transformation and the Retinex-based adaptive filter only in the brightness channel. We finally transfer them back to the RGB space after combining the new brightness and the original chromaticity together. Our model works well in keeping the chromaticity information. Global mapping only in the brightness channel is a good way to avoid desaturation. In addition, our model ensures a good independence between brightness and chromaticity. By applying our method on HDR images, the details in both dark areas and bright areas can be well displayed with better appearance in hue and saturation.