JPEG-HDR Brings True HDR Benefits to the JPEG Standard
The JPEG-HDR format stores all the data in high dynamic range beyond 8 bits, so that users can use this entire range to edit images during postprocessing. By comparison, the HDR modes on current smartphones automatically tone-map images based on proprietary algorithms and provide a single compressed image without the original HDR data, preventing postprocessing to the user's preference.
Tone Mapping: Not True HDR
Tone mapping is a technique used in image processing to map one set of colors to another to approximate the appearance of high-dynamic-range images in a medium that has a more limited dynamic range. Tone mapping addresses the problem of strong contrast reduction from the original scene radiance to the displayable range, while preserving the image details and color appearance that are important for appreciating the original scene content.
JPEG-HDR: Backward Compatible with Conventional JPEG
JPEG-HDR is a backward-compatible extension of JPEG, standardized by ISO toward high-dynamic-range photography. A legacy JPEG decoder will decode the baseline JPEG streams embedded in JPEG-HDR, typically tone-mapped 8-bit images. A JPEG-HDR decoder will be able to restore the complete HDR images using the additional data in the extended part of the new format.
JPEG-HDR files are typically 20 percent to 30 percent larger than conventional JPEG files.
Other HDR Formats: Limitations
HDR image formats exist, such as Radiance (.hdr) and Open EXR (.exr), but their files are typically 10 times larger than JPEG-HDR files, and are thus not suitable for many use cases, such as sharing and cloud syncing. Another format, JPEG-XR, can support HDR, but it failed to become popular in the consumer space because it lacks backward compatibility with JPEG.
Incorporating JPEG-HDR in Your Products
If you are a capture-device manufacturer, you can either build your own implementation or use an implementation developed by a third party. Please contact Dolby for more information.
If you are a PC software provider or a mobile app developer and are interested in supporting the JPEG-HDR format, you can build your own implementations based on the reference software implementation that we will publish soon. Please check this site in future to download this implementation.
JPEG-HDR Benefits for Developing Mobile Photo Apps
JPEG-HDR will deliver additional image data not previously available to you, greatly expanding your capabilities. For example, you can do better photo enhancements, and even better tone mapping. You can see image details that were not previously visible, which will help increase understanding of the images and help you create better storytelling for your end users. You can also support your users with better print quality.