High Dynamic Range Image Encodings 03 An important consideration for any digital image is how to store it. This is espe- cially true for high dynamic range (HDR) images, which record a much wider gamut than standard 24-bit RGB, and therefore require an efficient encoding to avoid tak- ing up an excess of disk space and network bandwidth. Fortunately, several HDR file encodings and formats have already been developed by the graphics community. A few of these formats have been in use for decades, whereas others have just recently been introduced to the public. An encoding is defined as the raw bit representation of a pixel value, whereas a format includes whatever wrapper goes around these pixels to compose a com- plete image. The quality of the results is mostly determined by the encoding rather than the format, making encodings the focus of this chapter. File formats includ- ing some type of "lossy" compression are the exception to this rule because the