Starting from Lightroom for mobile (iOS) version 9.0, you can export edited photos as Original, JPG,AVIF, JXL, TIF, and DNG, with HDR Output for AVIF and JXL. HDR-optimized images are also stored in JPG using Gain Map.
Gain Map provides a solution for a consistent and adaptive display of HDR images. Conceptually, this method combines both SDR and HDR renditions within a single image and interpolates between the two dynamically at display time. A Gain Map represents the quotient between the two renditions. The image file stores a Base rendition (SDR or HDR), the Gain Map, and some associated metadata. At display time, the Base image is combined with the scaled version of the Gain map, where the scale factor depends on the image metadata and the HDR capacity of the display. Gain Maps can be downsampled and compressed to save space. View Gain Map to learn more.
To export photos, follow these steps: