ISO 12234-4:2026
(Main)Digital imaging — Image storage — Part 4: Digital negative format
Digital imaging — Image storage — Part 4: Digital negative format
This document specifies the Digital Negative (DNG) image file format. A DNG file meets the requirements provided in this document.
Imagerie numérique — Stockage d'image — Partie 4: Format négatif numérique
General Information
- Status
- Published
- Publication Date
- 23-Mar-2026
- Technical Committee
- ISO/TC 42 - Photography
- Drafting Committee
- ISO/TC 42 - Photography
- Current Stage
- 6060 - International Standard published
- Start Date
- 24-Mar-2026
- Due Date
- 16-Feb-2026
- Completion Date
- 24-Mar-2026
Overview
ISO 12234-4:2025 is an international standard published by the International Organization for Standardization (ISO) under the technical committee ISO/TC 42/WG 18, with ANSI as the secretariat. This standard specifically defines the Digital Negative (DNG) image file format, originally developed and published by Adobe Systems as the “Digital Negative (DNG) Specification.”
The DNG format standardizes the storage and archival of raw image data captured by digital cameras, ensuring interoperability and long-term usability of digital negatives. It harmonizes the various proprietary raw image implementations into a consistent open format supported by major imaging and photo-processing applications.
Key Topics
The ISO 12234-4:2025 standard provides detailed specifications on multiple core aspects of the DNG format, including but not limited to:
- File Structure and Extensions: Defines the use of file extensions and the hierarchical organization of DNG files using TIFF sub-image file directories (SubIFDs).
- Metadata Handling: Specifies the critical metadata fields and tags that describe image capture information, camera profiles, image corrections, and other proprietary details.
- Pixel and Image Data Representation: Details how pixel data is encoded, including floating-point image data, defective and masked pixel handling, and the specification of transparency and enhanced image data.
- Camera Profiles and Color Processing: Clarifies the implementation of camera calibration matrices, profiles, and mapping from camera color spaces to CIE XYZ color space for color accuracy.
- Compatibility and Extensions: Covers limitations and new definitions for TIFF 6.0 tags, ensuring backward compatibility while accommodating new features unique to DNG.
- Image Processing Model: Provides a model for processing raw image values into linear and color-corrected outputs, incorporating the use of opcode lists for custom image transforms.
- Advanced Features: Includes support for proxy DNG files, depth maps, semantic masks, and 64-bit image data formats for enhanced precision.
Applications
The ISO 12234-4:2025 DNG standard is essential for professionals and organizations involved in digital imaging, photography, archiving, and software development:
- Camera Manufacturers: Can implement the open DNG format for raw image output, providing users with widely supported files and reducing proprietary format fragmentation.
- Photographers and Content Creators: Benefit from an industry-recognized raw file format that ensures better future-proofing and interoperability across imaging software.
- Imaging Software Developers: Gain a comprehensive and consistent format to support raw image editing, conversion, and archival functionalities.
- Digital Archives and Libraries: Utilize DNG for preserving raw digital images in a standardized, open format that includes extensive metadata and maintains image fidelity.
- Scientific and Industrial Imaging: Use DNG’s support for enhanced metadata and custom tags to store specialized sensor data with standard raw image data.
Related Standards
ISO 12234-4:2025 complements several other ISO standards and technical guidelines related to digital imaging and file formats, including:
- ISO 12234-1: General Image File Format – Specifies TIFF/EP, which serves as the base for DNG structure.
- ISO 12639: Digital Still Camera Image Metadata – Provides metadata guidelines for digital photography.
- ISO 19005 (PDF/A): Archival PDF standard, relevant for digital document preservation in which images may be embedded.
- TIFF 6.0 Specification: The foundational image file format on which DNG builds and provides extensions.
- Adobe DNG Specification: The original proprietary specification that ISO 12234-4 harmonizes with broader industry adoption.
By adhering to ISO 12234-4:2025, stakeholders ensure use of a robust, open standard for raw image capture, storage, and processing - essential for digital image quality, interoperability, and long-term digital asset management. The DNG format facilitates a consistent and future-proof approach to digital negative management across the imaging ecosystem.
Frequently Asked Questions
ISO 12234-4:2026 is a standard published by the International Organization for Standardization (ISO). Its full title is "Digital imaging — Image storage — Part 4: Digital negative format". This standard covers: This document specifies the Digital Negative (DNG) image file format. A DNG file meets the requirements provided in this document.
This document specifies the Digital Negative (DNG) image file format. A DNG file meets the requirements provided in this document.
ISO 12234-4:2026 is classified under the following ICS (International Classification for Standards) categories: 37.040.99 - Other standards related to photography. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 12234-4:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
International
Standard
ISO 12234-4
First edition
Digital imaging — Image storage —
2026-01
Part 4:
Digital negative format
Imagerie numérique — Stockage d'image —
Partie 4: Format négatif numérique
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .viii
Introduction .ix
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 DNG format . 3
4.1 Overview .3
4.2 File extensions .3
4.3 SubIFD trees .3
4.4 Byte order .3
4.5 Masked pixels .4
4.6 Defective pixels .4
4.7 Metadata .4
4.8 Proprietary data .4
4.9 Camera profiles .4
4.10 Opcode lists .5
4.11 Floating point image data .6
4.12 Transparency .6
4.13 Proxy DNG files .6
4.14 Depth maps .6
4.15 Enhanced image data .7
4.16 Semantic masks .7
4.17 64-bit format .8
5 Restrictions and extensions to existing TIFF 6.0 tags . 8
5.1 NewSubFileType .8
5.1.1 Previews .8
5.1.2 Transparency . . .9
5.1.3 Depth maps.9
5.1.4 Enhanced image data .9
5.1.5 Semantic masks .9
5.2 BitsPerSample .9
5.3 SampleFormat .9
5.4 Compression .9
5.5 Predictor .10
5.6 PhotometricInterpretation .11
5.7 Orientation .11
6 DNG image processing model .11
6.1 Mapping raw values to linear reference values .11
6.1.1 Linearization . . 12
6.1.2 Black subtraction . 12
6.1.3 Rescaling (normalization) . 12
6.1.4 Clipping . 12
6.2 Mapping camera colour space to CIE XYZ space . 12
6.2.1 Camera calibration matrices . 12
6.2.2 One, two, or three colour calibrations . 12
6.2.3 Definitions used in the following sections . 13
6.2.4 Translating white balance xy coordinates to camera neutral coordinates . 13
6.2.5 Translating camera neutral coordinates to white balance xy coordinates .14
6.2.6 Camera to XYZ (D50) transform .14
6.3 Applying the hue/saturation/value mapping table . 15
6.3.1 Special compatibility note with DNG 1.2 .16
6.4 Opcodes .16
iii
7 DNG tags . 17
7.1 ActiveArea .17
7.2 AnalogBalance .17
7.3 AntiAliasStrength .18
7.4 AsShotICCProfile . .18
7.5 AsShotNeutral .19
7.6 AsShotPreProfileMatrix .19
7.7 AsShotProfileName . 20
7.8 AsShotWhiteXY . 20
7.9 BaselineExposure . 20
7.10 BaselineExposureOffset .21
7.11 BaselineNoise . .21
7.12 BaselineSharpness . 22
7.13 BayerGreenSplit . 22
7.14 BestQualityScale . 23
7.15 BlackLevel . 23
7.16 BlackLevelDeltaH . 23
7.17 BlackLevelDeltaV .24
7.18 BlackLevelRepeatDim .24
7.19 CalibrationIlluminant1 .24
7.20 CalibrationIlluminant2 . 25
7.21 CalibrationIlluminant3 . 25
7.22 CameraCalibration1 . 26
7.23 CameraCalibration2 . 26
7.24 CameraCalibration3 . 26
7.25 CameraCalibrationSignature .27
7.26 CameraSerialNumber .27
7.27 CFALayout .27
7.28 CFAPattern . 28
7.29 CFAPlaneColour . 29
7.30 CFARepeatPatternDim . 29
7.31 ChromaBlurRadius. 29
7.32 ColourimetricReference . 30
7.33 ColourMatrix1 . 30
7.34 ColourMatrix2 .31
7.35 ColourMatrix3 .31
7.36 ColumnInterleaveFactor .31
7.36.1 Potential usage .32
7.37 CurrentICCProfile .32
7.38 CurrentPreProfileMatrix .32
7.39 DefaultBlackRender .32
7.40 DefaultCropOrigin . 33
7.41 DefaultCropSize . 33
7.42 DefaultScale. 34
7.43 DefaultUserCrop . 34
7.44 DepthFar . 34
7.45 DepthFormat . 35
7.46 DepthMeasureType . . 35
7.47 DepthNear. 35
7.48 DepthUnits . 36
7.49 DNGBackwardVersion . 36
7.50 DNGPrivateData . 36
7.51 DNGVersion .37
7.52 EnhanceParams .37
7.53 ExtraCameraProfiles.37
7.54 ForwardMatrix1 . 38
7.55 ForwardMatrix2 . 38
7.56 ForwardMatrix3 . 38
7.57 IlluminantData1 . 39
iv
7.58 IlluminantData2 . 40
7.59 IlluminantData3 . 40
7.60 ImageSequenceInfo . 40
7.61 ImageStats .41
7.62 JXLDistance . 44
7.63 JXLEffort . 44
7.64 JXLDecodeSpeed .45
7.65 LensInfo .45
7.66 LinearizationTable . .45
7.67 LinearResponseLimit . . 46
7.68 LocalizedCameraModel . 46
7.69 MakerNoteSafety . 46
7.70 MaskedAreas . .47
7.71 MaskSubArea .47
7.71.1 Example . 48
7.72 NewRawImageDigest . 49
7.73 NoiseProfile . 49
7.74 NoiseReductionApplied . 50
7.75 OpcodeList1 . 50
7.76 OpcodeList2 . 50
7.77 OpcodeList3 .51
7.78 OriginalBestQualityFinalSize .51
7.79 OriginalDefaultCropSize .51
7.80 OriginalDefaultFinalSize .52
7.81 OriginalRawFileData .52
7.82 OriginalRawFileDigest . 53
7.83 OriginalRawFileName . 54
7.84 PreviewApplicationName . 54
7.85 PreviewApplicationVersion . 54
7.86 PreviewColourSpace . 55
7.87 PreviewDateTime . 55
7.88 PreviewSettingsDigest . 55
7.89 PreviewSettingsName . 56
7.90 ProfileCalibrationSignature . 56
7.91 ProfileCopyright. 56
7.92 ProfileDynamicRange .57
7.93 ProfileEmbedPolicy . 58
7.94 ProfileGainTableMap .59
7.95 ProfileGainTableMap2 . 60
7.95.1 DataType .61
7.95.2 Gamma .62
7.95.3 GainMin and GainMax .62
7.95.4 Application .62
7.95.5 Compatibility with ProfileGainTableMap .62
7.95.6 IFD 0 vs Camera Profile IFD . 63
7.95.7 IFD 0 vs Raw IFD . 63
7.96 ProfileGroupName . . 63
7.97 ProfileHueSatMapData1 . 64
7.98 ProfileHueSatMapData2 . 64
7.99 ProfileHueSatMapData3 . 64
7.100 ProfileHueSatMapDims . 65
7.101 ProfileHueSatMapEncoding . 65
7.102 ProfileLookTableEncoding . 66
7.103 ProfileLookTableData .67
7.104 ProfileLookTableDims . 68
7.105 ProfileName . 68
7.106 ProfileToneCurve . 68
7.107 RawDataUniqueID . 69
7.108 RawImageDigest . 69
v
7.109 RawToPreviewGain .70
7.110 ReductionMatrix1 .70
7.111 ReductionMatrix2 .70
7.112 ReductionMatrix3 . .71
7.113 RGBTables .71
7.113.1 General .71
7.113.2 Notes on the tag fields . 72
7.113.3 Background table . 73
7.113.4 Table transform pipeline .74
7.113.5 Notes on applying the colour transforms . . 75
7.114 RowInterleaveFactor .76
7.115 SemanticInstanceID . 77
7.116 SemanticName . 77
7.117 SubTileBlockSize . 77
7.118 UniqueCameraModel . 78
7.119 WhiteLevel . 78
8 Opcodes .78
8.1 DeltaPerColumn . 79
8.1.1 Syntax . . 79
8.1.2 Description . 79
8.2 DeltaPerRow . 80
8.2.1 Syntax . . 80
8.2.2 Description . 80
8.3 FixBadPixelsConstant . 81
8.3.1 Syntax . . 81
8.3.2 Description . 81
8.4 FixBadPixelsList . 81
8.4.1 Syntax . 81
8.4.2 Description . 82
8.5 FixVignetteRadial . 82
8.5.1 Syntax . . 82
8.5.2 Description . 82
8.6 GainMap . 83
8.6.1 Syntax . . 83
8.6.2 Description . 84
8.7 MapPolynomial . . 85
8.7.1 Syntax . . 85
8.7.2 Description . 85
8.8 MapTable . 86
8.8.1 S
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