High Dynamic Range Image and Video Data Compression

Although high dynamic range (HDR) image and video are becoming common in many computer graphics applications, their data compression has received little attention so far. In this paper, we propose a practical approach to HDR video compression for efficient storage and fast transmission. Most current HDR images and videos are created from multiple exposures of the scene with varying exposures or varying fstops. Common HDR pixel representations use formats that are comprised of a base color and a common exponent. We compress the base color component by adaptive JPEG compression scheme. Our experiment shows that the quality of the HDR images is very sensitive to the noise introduced in lossy image compression schemes. Hence we compress the common exponent using a lossless compression scheme. The strong coherence in the common exponent of most HDR image allows us a high compression rate even though it is compressed in lossless mode. The primary contribution of this paper is the observation that high dynamic range image and video data are naturally separated into a base color component and common exponent component. The base color component may be thought of as a standard image/video, and hence existing image/video compression techniques can be used to compress this component. We suppress the introduction of artifacts by applying adaptive quantization coefficients. The color component is compressed using lossy or lossless image compression method. The common exponent component is compressed using a lossless image compression method. Because of the spatial coherence in the common exponent component, its compression ratio is very high and hence the sizes of the compressed HDR image/video are comparable to those of non HDR image/video. Thus we provide a simple, yet efficient approach to HDR image/video data compression.