libultrahdr is an image compression library that uses gain map technology to store and distribute HDR images. Conceptually on the encoding side, the library accepts SDR and HDR rendition of an image and from these a Gain Map (quotient between the two renditions) is computed. The library then uses backward compatible means to store the base image (SDR), gain map image and some associated metadata. Legacy readers that do not support handling the gain map image and/or metadata, will display the base image. Readers that support the format combine the base image with the gain map and render a high dynamic range image on compatible displays.
For additional information, see android hdr-image-format guide.
Build from source using CMakeThis software suite has been built and tested on platforms:
Refer to building.md for complete instructions.
A detailed description of libultrahdr encode and decode api is included in ultrahdr_api.h and for sample usage refer demo app.
libultrahdr includes two classes of APIs, one to compress and the other to decompress HDR images:
Scenario Hdr intent raw Sdr intent raw Sdr intent compressed Gain map compressed Quality Exif Use Case API - 0 P010 or rgba1010102 or rgbaf16 No No No Optional Optional Used if, only hdr raw intent is present. 1 API - 1 P010 or rgba1010102 or rgbaf16 YUV420 or rgba8888 No No Optional Optional Used if, hdr raw and sdr raw intents are present.2 API - 2 P010 or rgba1010102 or rgbaf16 YUV420 or rgba8888 Yes No No No Used if, hdr raw, sdr raw and sdr compressed intents are present.3 API - 3 P010 or rgba1010102 or rgbaf16 No Yes No No No Used if, hdr raw and sdr compressed intents are present.4 API - 4 No No Yes Yes No No Used if, sdr compressed, gain map compressed and GainMap Metadata are present.5Configure display device characteristics (display transfer characteristics, max display boost) for optimal usage.
Input Usage max_display_boost (optional, >= 1.0) the maximum available boost supported by a display. supported color transfer format pairs color transfer Color format SDR 32bppRGBA8888 HDR_LINEAR 64bppRGBAHalfFloat HDR_PQ 32bppRGBA1010102 PQ HDR_HLG 32bppRGBA1010102 HLGTonemap hdr to sdr. Compute gain map from hdr and sdr. Compress sdr and gainmap at quality configured. Add exif if provided. Combine sdr compressed, gainmap in multi picture format with gainmap metadata. ↩
Compute gain map from hdr and sdr. Compress sdr and gainmap at quality configured. Add exif if provided. Combine sdr compressed, gainmap in multi picture format with gainmap metadata. ↩
Compute gain map from hdr and raw sdr. Compress gainmap. Combine sdr compressed, gainmap in multi picture format with gainmap metadata. ↩
Decode compressed sdr input. Compute gain map from hdr and decoded sdr. Compress gainmap. Combine sdr compressed, gainmap in multi picture format with gainmap metadata. ↩
Combine sdr compressed, gainmap in multi picture format with gainmap metadata. ↩
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4