Full Name	Digital Negative file format
Format ID	IG_FORMAT_DNG = 108
File Extension(s)	*.dng
Data Type	Raster image
Data Encoding	Binary
Color Profile Support	No
Multi-Page Support	No
Alpha Channel Support	No
ImageGear Platforms Support	WIN32, WIN64, Unix, Unix64, MAC

ImageGear Supported Versions:

• Version 1.0.0.0
• Version 1.1.0.0 - fixed incompatibility in JPEG Lossless compression, added new tags

ImageGear Supported Features:

• IG_FLTR_DETECTSUPPORT - autodetection
• IG_FLTR_PAGEREADSUPPORT - single page file reading

ImageGear Read Support:

• IG_COMPRESSION_NONE:
  • Grayscale: 9..16 bpp
  • RGB: 24, 48 bpp *
• IG_COMPRESSION_JPEG:
  • Grayscale: 16 bpp
  • RGB: 24, 48 bpp *

* 8bpc DNG loading has been enabled via promoting the image to 16bpc before loading.

ImageGear Write Support:

None

ImageGear Filter Control Parameters:

Filter Control Parameter	Type	Default Value	Available Values	Description
APPLY_COLORSPACE_CONVERSION	AT_BOOL	TRUE	TRUE, FALSE	Set to TRUE to convert raw image to linear sRGB color space during loading. Has effect only if RECONSTRUCT_COLORS is TRUE.
APPLY_TONE_CORRECTION	AT_BOOL	TRUE	TRUE, FALSE	Set to TRUE to automatically adjust image tone and apply sRGB gamma correction during loading. Has effect only if bothRECONSTRUCT_COLORS and APPLY_COLORSPACE_CONVERSION are TRUE.
RECONSTRUCT_COLORS	AT_BOOL	TRUE	TRUE, FALSE	ImageGear attempts to reconstruct full color image from the camera raw image. Otherwise, ImageGear loads raw pixel data without any processing.

Comments

This file format was developed by Adobe as a non-proprietary format for unified storage of "raw" images from digital cameras. DNG image stores unprocessed pixel data obtained from camera's sensor, and keeps information about color, contrast and brightness adjustments, sharpening, as well as many other parameters, in its tags. This provides greater possibilities for image correction and enhancement, compared to commonly used formats such as JPEG, EXIF or TIFF.

The fact that the format is non-proprietary allows software vendors to provide support for DNG in their applications, with complete control over the image reconstruction process.

DNG extends TIFF/EP format. It adds a set of new tags for parameters that control reconstruction of full color image from the raw data.

References Used

ADOBE SYSTEMS INCORPORATED. Digital Negative (DNG) specification.