All about DNG files
DNG stands for Digital Negative and is an open RAW format released by Adobe on September 27, 2004. I think the name (much like “RAW”) does a very good job of explaining what the files contain: the unaltered(*) raw data of the photograph—essentially a digital negative. Apple has also been using the format since the iPhone 12 Pro and 12 Pro Max.[1]
As we know today, Adobe did not achieve its original goal of establishing a uniform raw format for all manufacturers. Almost every major manufacturer has established its own format. Unlike most proprietary formats from other manufacturers (such as CR2, NEF, or ARW), the DNG specification is publicly documented, and Adobe grants royalty-free use provided the implementation complies with the specification.[2] The Library of Congress recommends DNG as an archival format for photographs (to ensure long-term readability).[3]
Versions and Development
| Version | Year | Major change |
|---|---|---|
| DNG 1.0 | September 2004 | First version, together with Adobe DNG Converter |
| DNG 1.1 | February 2005 | Linearization tables, color calibration |
| DNG 1.2 | May 2008 | New camera profiles |
| DNG 1.3 | June 2009 | Opcodes for lens correction |
| DNG 1.4 | October 2012 | Transparency, 32-bit HDR, lossy compression |
| DNG 1.5 | November 2019 | BigTIFF for files >4 GB, semantic masks |
| DNG 1.6 | December 2020 | Foundation for Apple ProRAW |
| DNG 1.7 | June 2023 | JPEG-XL support |
Apple ProRAW
With iOS 14.3, Apple introduced the ProRAW format in December 2020. The format is technically based on DNG 1.6 and combines the raw data from iPhone cameras with Apple’s image processing (such as Deep Fusion and Smart HDR). Everything is saved as 12-bit linear DNG in files ranging from approximately 25 MB (12 MP) to 75 MB (48 MP).
Cameras with native DNG support
Some manufacturers offer native DNG support: Leica (since the Digital Module R in 2005), Hasselblad, Pentax, Ricoh, and Casio on select models. Drones from DJI and Yuneec, as well as various Android smartphones, also save directly in the open DNG format. For maximum flexibility and archiving capabilities, the open DNG format is a strong selling point.
Technical basis: TIFF 6.0 and TIFF-EP
Technically, DNG is based on an extension of the TIFF 6.0 format and is compatible with the TIFF-EP standard (ISO 12234-2). TIFF-EP was defined in 2001 specifically for digital cameras and specifies how raw data from camera sensors is structured and stored—including information about the sensor’s Bayer matrix. DNG extends this standard with additional tags for lens corrections, color profiles, and camera calibration. Metadata (EXIF, IPTC, XMP) is stored directly in the file; separate sidecar files (files stored alongside the image that contain the metadata) are not required.
(*) Since DNG 1.4, images can also be compressed with loss, in which case the data is no longer unaltered.
Sources
[1] support.apple.com – About Apple ProRAW
[2] helpx.adobe.com – Digital Negative (DNG)
[3] loc.gov – Adobe Digital Negative (DNG)
Convert, open and edit DNG files
Details about DNG files
- Software for opening DNG files
- Software for editing DNG files
- MIME-type for DNG
- image/x-adobe-dng
No Comments