Digital+Negative+(DNG)

Digital Negative (DNG)
toc The digital negative is a derivative of TIFF 6 file format that combines the archvial prowess of the TIFF format with the extensive sensor metadata of the RAW file format. The DNG was developed by Adobe to be an open standard that can replace the RAW image fileformat.

The DNG while not accepted as an archival standard has the potential to supplant TIFF in the future. In Michael J. Bennett’s and F.Barry Wheeler article “Raw as Archival Still Image Format: A Consideration” describes the benefits of Raw as an archival standard and DNG in particular. Bennet and Wheeler say, “the open and fully documented DNG raw standard retains the common virtues of raw formats while also offering additional archival value “ (p. 7). Among the advantages are, XMP computable for custom metadata, embedded TIFF file,TIFF-EP subset, embedded RAW, and “JPEG previews based upon parametric editing adjustments” ( p.7). The highly customizable Metadata is the main virtue of DNG. With the DNG the archivist would have access to the sensor metadata and a customizable file format that allows administrative, descriptive, and technical metadata to be embedded directly into the file. The ability to embed any form of metadata makes it an ideal archival alterative.

DNG is a robust image file format that combines the best of RAW and TIFF to be a living file format. The main disadvantage of the TIFF file format is that it does not carry any of the camera metadata making it a stagnat file format. The derivatives cannot be modified based off sensor data only manipulated through photograph editing software. The DNG carries the direct sensor information which allows rendering through pragmatic image editing. The metadata carries the information necessary to modify the picture through metadata such as the white balance, noise, and color temperature( p.3). This makes it an attractive archival alternative to RAW, TIFF, and JPG2000 because it offers an adjustable open standard that has configruable metadata. DNG offers a sustainable file format that can grow with technology instead of fading into obsolescence that most proprietary RAW formats offer.

Future of the DNG FIle Format
The future of DNG is vague at best. While it offers libraries, museums, and other digital image repositories a robust open file format adoption has not been widespread. DNG has gained some traction in the photography community but is still not widly known or trusted among the archival community. This is in part due to the domance of the TIFF file format and that archivist are not known to be addaptiable. Bennet and Wheeler report, “DNG is currently adopted as an archival master format at The National Gallery of Art, Washington, D.C. and at The Art Institute of Chicago” (p.9). The main problem that DNG faces as a archival file format is adoption. As with JPG2000 before it, DNG still has not been widely adopted by either users or camera manufactures. Most notably Cannon, Nikon, and Sony have not adopted the DNG standard(p.3). Right now only the smaller manufactures support the standard such as Pentax, Lacie, and Sigma. Sigma has Foveon image sensor which could utilize DNG to record the extra data from the Foveon X3 direct image sensor.

The lack of adoption is likely some mix of mistrust of Adobe and camera manufactures want to support their proprietary RAW format to lock them into their own ecosystem. ISO also does not support the DNG file format. The complexity of the file format is both its greatest strength and weakness. The format offers completely lossless compression, smaller file size, and superb image clarity but it is harder to work with and less familar to the archival community than a TIFF. DNG requires Adobe’s DNG developer program to work with and adoption among other image editing software is inconsistent. Even with the advantages of DNG as an archival standard it is hard to break the hold that TIFF has had on digital image collections.

The More you Know...About DNG
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Creation of a DNG
A DNG is essentially a standardized format of the RAW file format with extended Metadata capabilities. A RAW is fundamentally the "raw" data from a camera's sensor. The creation of a RAW is the, " mosaiced raw image sensor data is simply a record of luminance values at each sensor element or what in essence is a grayscale image. Additionally, however, what is also recorded in the file are the characteristics of the camera manufacturer's color filter array or mosaic (usually arranged in a Bayer pattern) that is applied over the individual sensor elements" (p.3). Embedded with in this information is a preview JPEG. The RAW is then converted by either the camara manufactures proprietary software or any other photoedting software (adobe Lightroom, Adobe Bridge, or Aperture). A RAW can become a DNG a few different ways.The camera can support DNG natively such as Pentax. Pentax writes a DNG skipping the RAW format completely. Most others fist shoot in raw and then is converted to DNG with in the camera. The other option is to convert a RAW file to the DNG format. Adobe offers a free digital converter for DNG and some software providers will convert a RAW into DNG. The DNG also has the property RAW data embedded with in the file that can later be separated if needed. The DNG is still facing resistance from major camera manufactures that don’t allow some sensor data to be converted to the DNG file format.

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**References**
Adobe. (2011). Extensible Metadata Platform (XMP). Retrieved from []

Bennett, M. J. & Wheeler, F. Barry.(2010). "Raw as Archival Still Image Format: A Consideration” . UConn Libraries Published Works. Paper 23. Retrieved from []

Adobe. (2007) Introducing the Digital Negative Specification. Retrieved from []

dpBestflow.org. (2011). Archive File Formats. Retrieved from []

Sustainability of Digital Formats Planning for Library of Congress. (2007). //Adobe Digital Negative (DNG), Version 1.1// Retrieved from http://www.digitalpreservation.gov/formats/fdd/fdd000188.shtml

Universal Photographic Digital imaging Guidelines. (2008). Archiving .Retrieved from []