1libultrahdr is an image compression library that uses gain map technology 2to store and distribute HDR images. Conceptually on the encoding side, the 3library accepts SDR and HDR rendition of an image and from these a Gain Map 4(quotient between the two renditions) is computed. The library then uses 5backward compatible means to store the base image (SDR), gain map image and 6some associated metadata. Legacy readers that do not support handling the 7gain map image and/or metadata, will display the base image. Readers that 8support the format combine the base image with the gain map and render a 9high dynamic range image on compatible displays. 10 11For additional information, see android hdr-image-format 12https://developer.android.com/guide/topics/media/platform/hdr-image-format. 13