Evaluation of floating point image compression

Recently, compression of High Dynamic Range (HDR) photography gained attention in the standardization of the Microsoft HDPhoto compression scheme as JPEG-XR. While integer data of 16 bits/pixel (bpp) in scRGB color-space can represent images up to a dynamic range of about 3.5 magnitudes in luminance, even higher ranges are more efficiently represented by floating-point number formats. In this work, the author presents the approach taken by JPEG-XR for compressing such data, and shows that this method when applied to JPEG 2000 generates equally good results. Furthermore, it is shown that the method performs nearly optimal under a mathematical quality index that is closely related to SSIM, and to the mean square error of the HDR images when rendered to the LDR regime.