DNG to EXR Converter

Encoding: the DNG uses lossless (or lossy) JPEG-compressed sensor data, plus optional JPEG previews; EXR uses none, RLE, ZIP, PIZ, PXR24, B44 or DWA, chosen per file, and the download is a ZIP-compressed OpenEXR with 16-bit half-float channels, the 8-bit sRGB values converted to linear light.

Bit depth: 8 to 16 bits per channel in the DNG; EXR allows 16-bit half or 32-bit floating point per channel, and the EXR written here has 16-bit half float per channel. The raw data's 12 to 16 bits are not used: the embedded 8-bit preview is converted.

Colour: camera RGB plus the colour matrices that map it to XYZ (demosaiced linear RGB in a Linear DNG) in the DNG; EXR supports scene-linear RGB, often ACEScg or linear Rec.709, written here as linear-light RGB.

Metadata: the DNG can carry EXIF, XMP and DNG tags for colour matrices, calibration and lens corrections; EXR can carry named header attributes such as chromaticities, timecode and camera data, but nothing is copied across.

DNG is Adobe's openly documented raw format. Some cameras and phones record it directly, Adobe DNG Converter turns other brands' raw files into it, and a Linear DNG holds already-demosaiced RGB that raw editors treat like any other raw file.

DNG is built on TIFF/EP. The raw image sits in a sub-IFD marked as the main image, with tags for black and white levels, colour matrices and the colour filter pattern; a Linear DNG (PhotometricInterpretation 34892) stores demosaiced RGB instead of a mosaic. Previews are optional, and Adobe DNG Converter can write a medium (1024 px), full-size or no preview.

DNG files usually come from Leica, Pentax and Ricoh cameras, DJI drones, Google Pixel and iPhone ProRAW, and Adobe DNG Converter.

OpenEXR is the high dynamic range format of film visual effects. It stores half or full floating-point channels in linear light, plus any extra render passes, and is the working format of compositing pipelines.

An EXR starts with the magic number 76 2F 31 01 and a version field, then a header of named, typed attributes (channels, compression, dataWindow, displayWindow) and a table of offsets to scanline or tile blocks.

EXR is the better choice for visual effects, compositing and 3D render output, while DNG suits raw editing and archiving raw files in an open format.

EXR strengths: True high dynamic range in linear light; Any number of channels and render passes; Lossless compression options. Drawbacks to weigh: Needs tone mapping to look right on a normal screen; Very large files; No browser or phone support.