Digital Negative

The Digital Negative (DNG, dt digital negative ) format is an imagined in September 2004 raw data format that has been developed according to the manufacturer Adobe with the aim to replace the various proprietary formats of the manufacturers and to establish itself as a standard.

Use

Adobe has revealed the specifications of the format and provides further information ready for implementation. In addition to the in-house image processing software Adobe Photoshop (version CS ), Adobe Photoshop Elements (version 3.0) and Adobe Photoshop Lightroom also support third-party programs that format, for example

As well as the free software DCRaw.

Also, there are converters for the conversion of RAW to DNG files, for example, the program digiKam.

The shipped in 2005 Leica Digital-Modul- R format was first used directly for storage of image data. The Hasselblad H2D was the first digital SLR that can store either in their own or in DNG RAW format; it was followed by other manufacturers:

  • Samsung ( per 815)
  • Ricoh (GR Digital)
  • Leica (S- system, M - System) and X series (Leica X2 and X1)
  • Hasselblad / Imacon H2D,
  • Pentax (optional use of its own PEF format or DNG)

Technical implementation

The format is based on an expansion of the Tagged Image File Format / Electronic Photography (short tiff / ep ). In addition to the image data any metadata can be embedded. This allows - even extensive - extensions that can without compatibility loss at any time be integrated and thereby do not require separate so-called sidecar files ( a similar or redundant data storage ) and enables high portability of files between different computer platforms. DNG allows transparencies and 32 -bit color depth

Pros and Cons

In addition to the advantages already known from the underlying RAW format are:

  • This in contrast to most existing raw formats openly documented file format facilitates the development of software by third parties, both for writing and for reading.
  • Lossless compression is possible, but not obligatory and is done - unlike the underlying TIFF format - according to specified conditions, which should further improve the portability.
  • DNG does not require that raw data in mosaic form ( according to a Bayer color array ). It therefore supports for example, Sigma cameras with Foveon sensor.

In practice, arising at least so far also disadvantages:

  • Larger file sizes, for example, compared to Sony's ARW format (but also some other camera makers ).
  • So far, aside from the above exceptions, cameras with native DNG support rare, so that the individual Bildbearbeitsprozess must be added to the intermediate step of conversion.
  • Even cameras that supports DNG often implement the format does not fully (eg waiver of lossless compression, limited or incomplete installation of metadata).
Adobe Systems Aperture (Software) Data conversion Leica X1 Sigma Corporation Foveon X3 sensor
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