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 12234-4:2026 is the fourth part of the ISO 12234 series dedicated to digital imaging standards. This document specifies the Digital Negative (DNG) image file format, establishing comprehensive requirements for storing raw digital image data. DNG files provide a platform-independent, publicly documented format designed to enhance the interoperability of raw image files from digital cameras and imaging devices.
By standardizing DNG, ISO aims to support long-term image preservation, facilitate photographic workflows, and enable consistent processing of image data across various software and hardware environments. The DNG specification helps both device manufacturers and software developers achieve greater compatibility and reliability in digital imaging.
Key Topics
ISO 12234-4:2026 covers several essential areas related to the DNG image format:
- File Structure and Compatibility: Details the organization of DNG files, including supported file extensions, subIFD trees (Image File Directories), and compliance with existing TIFF 6.0 tags and structures.
- Handling of Image Data: Covers aspects such as byte order, masked and defective pixels, floating-point image data, and enhanced image data capabilities, ensuring robust and flexible storage of a wide range of raw data types.
- Metadata and Camera Profiles: Specifies metadata attributes, including camera model, calibration matrices, white balance data, color space mappings, and support for embedded or referenced camera profiles.
- Support for Advanced Features: Includes mechanisms for proxy DNG files, transparency layers, depth maps, semantic masks, and 64-bit format support, accommodating modern imaging requirements.
- Customization and Proprietary Information: Provides for the inclusion of proprietary metadata within a standardized framework, enabling manufacturers to extend DNG functionality while maintaining overall compliance.
Applications
The ISO 12234-4:2026 standard delivers significant value in various digital imaging contexts:
- Digital Camera Manufacturers: Ensures that captured raw images are stored in a widely recognized, interoperable format, reducing vendor lock-in and enhancing customer trust.
- Archival and Preservation: Supports the long-term storage and accessibility of digital negatives, making it suitable for museums, libraries, and institutions concerned with digital heritage.
- Photo Editing and Processing Software: Enables developers to reliably implement import, editing, and export capabilities for raw images, providing consistent user experiences and color management.
- Workflow Integration: Supports both amateur and professional photography workflows by allowing seamless transition of raw image data across different devices and software solutions.
- Research and Scientific Imaging: Provides a stable and extensible format for use in documentation, analysis, and sharing of raw image data acquired in scientific studies.
Related Standards
ISO 12234-4:2026 is part of a broader family of standards addressing digital photography and imaging, including:
- ISO 12234 Series: Encompasses additional parts detailing other image storage requirements and formats, complementing the DNG file format specification.
- TIFF 6.0 (Tagged Image File Format): The foundational file structure upon which DNG is based, ensuring backward compatibility and widespread software support.
- Other ISO Digital Imaging Standards: Such as standards for color management, file interchange, and metadata within the broader ISO digital imaging framework.
Manufacturers and developers seeking to achieve the highest levels of image fidelity, compatibility, and preservation are encouraged to reference ISO 12234-4:2026 alongside these related standards to optimize their digital imaging solutions.
Keywords: ISO 12234-4:2026, Digital Negative, DNG file format, digital imaging, image storage, raw image data, interoperability, camera profiles, metadata, image preservation, TIFF compatibility.
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
CP 401 • Ch. de Blandonnet 8
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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