Color correction of high dynamic range images at HDR-level

Abstract

In recent research in representing realistic appearance of materials, HDR(High Dynamic Range) images constructed from LDR(Low Dynamic Range) images taken with different exposure time using a digital camera are used to measure radiance of materials like BRDF. However, in order to reproduce the original color of the materials, they require color correction of the HDR images. Before constructing an HDR image, the color of each LDR image is corrected by using the ICC profile or other method. Then they make a color corrected HDR image from the color corrected LDR images [Goesele et al. 2001]. We call this method the LDR-level color correction. However, each pixel value of LDR images represents not only color but also intensity. Since the pixel values of the LDR images are modified for color correction before making an HDR image, the intensity of each pixel is also changed. In this paper, we propose a color correction method at HDR-level, where the correction is made after the HDR image is constructed. This gives a much better reproduction of the original color of a given material in our experiment.