Digital Negative - Versions of The Specification

Versions of The Specification

All versions of the specification remain valid, in the sense that DNG files conforming to old versions should still be read and processed by DNG readers capable of processing later versions. DNG has a version scheme built into it that allows the DNG specification, DNG writers, and DNG readers, to evolve at their own paces. Each version of the specification describes its compatibility with previous versions., published September, 2004
This version accompanied the launch of DNG and related products. It was a rare, possibly unique, example of a raw image format specification published by its owner. It was adequate for representing typical images, but it had a few errors and deficiencies (specifically the lack of support of "masked pixels" and an inadvertent deviation from the JPEG specification) that required it soon to be replaced by the next version., published February, 2005
This version corrected the flaws in the first version. It has proved capable of representing raw images for a large variety of cameras (both when written in-camera or via conversion from other raw image formats) for a few years, and it is the version still typically written in-camera., published May 2008
This version was based on experience and feedback from other companies about DNG since its launch. It introduced many new features, especially several new options for color specification under the general heading of "Camera Profiles". These are mainly of value to software products wanting their own flavor of color handling. This version permits administrative control of Camera Profiles, including calibration signatures and copyright information., published June, 2009
This version added various improvements, but the major change was to introduce "Opcodes". A Opcode is an algorithm to be applied to some or all of the image data, described in the specification, and (optionally) implemented in the product that reads and processes the DNG file. The DNG file itself holds lists of Opcodes to be executed, together with the parameters to be applied on execution. In effect, the DNG file can contain lists of "function calls" to be executed at various stages in the raw conversion process. For example, the WarpRectilinear Opcode "applies a warp to an image and can be used to correct geometric distortion and lateral (transverse) chromatic aberration for rectilinear lenses". This is an example of an algorithm that cannot be applied to the raw image data itself before it is placed into the DNG file, because it should be executed after demosaicing. There are 13 Opcodes described in this version, and each Opcode is accompanied by a specification version so that more can be added in future., published Sept., 2012
This version added Floating Point Image Data, Transparent Pixels, Proxy DNG Files, and additional tags. It also added SampleFormat and Predictor.
CinemaDNG, published September 2009
CinemaDNG uses DNG for each frame of a movie clip. There are additional tags specifically for movies: TimeCodes and FrameRate. It is not clear whether these tags will be added to a later version of the DNG specification, or will remain separately described only in the CinemaDNG specification.

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