Camera RAW Formats and Their Licenses

Building software that handles RAW files surfaces a set of questions that ordinary image formats never raise. The formats themselves are vendor-specific and undocumented, the decoder libraries tend to carry copyleft licenses, and official vendor SDKs sit behind an application and an agreement. This article works through those points against primary sources.

1. Where RAW formats actually stand

RAW is not one format. It is an umbrella term for a family of vendor-specific, often model-specific formats: Canon's CR2 and CR3, Nikon's NEF, Sony's ARW, Panasonic's RW2, Fujifilm's RAF, Sigma's X3F, and many more.

Most of them build on the TIFF structure (IFDs), but the core parts, such as the sensor data compression and the color matrices, live in vendor-private territory, and there is generally no published specification. The vendor SDK pages we checked back this up. Fujifilm is explicit about it on the Camera Control SDK page:

Source: FUJIFILM Camera Control SDK (checked 2026-07-20)

In other words, open source RAW decoders can read these formats not because the vendors published specifications, but because developers analyzed the files and implemented support. That fact is what leads to the reverse engineering question later in this article.

2. Open source RAW decoders

Here is the overview. In each case we read the license document itself, or the license file in the repository.

2-1. LibRaw: a dual license you choose between

LibRaw is the de facto default for RAW decoding. The repository's COPYRIGHT says the software is offered "under the terms of the one of two licenses as you choose." Reading the top of the actual license files confirms the versions:

• LICENSE.LGPL opens with "GNU LESSER GENERAL PUBLIC LICENSE, Version 2.1, February 1999". That is 2.1, not LGPL 3.
• LICENSE.CDDL opens with "COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0".

Sources: LibRaw COPYRIGHT / LICENSE.LGPL / LICENSE.CDDL (all checked 2026-07-20)

As for what each choice demands, LibRaw's own explanation runs roughly as follows. Under LGPL 2.1, you use the library as a shared library and publish any changes you make to the library itself under LGPL 2.1. CDDL 1.0 is described as more permissive, in that you are not forced to publish your changes to the library. Attribution is required either way, and a signed written agreement is not needed.

Source: libraw.org/node/2228 (checked 2026-07-20)

2-2. Two things people miss about LibRaw

(1) The demosaic packs are licensed differently. LibRaw has add-ons in separate repositories, LibRaw-demosaic-pack-GPL2 and LibRaw-demosaic-pack-GPL3, which are GPL v2 or later and GPL v3 or later respectively. If you link them at build time, your build becomes subject to the GPL, which defeats the point of choosing LGPL or CDDL. Check your build options.

Sources: demosaic-pack-GPL2 / demosaic-pack-GPL3 (checked 2026-07-20)

(2) The separate commercial license no longer exists. LibRaw was once offered as a three-way choice of LGPL2, CDDL, or LibRaw's own license, but the proprietary option was dropped in the 0.18 release, and the project announced that signed agreements had expired. The assumption that "you can pay for a commercial license to sidestep copyleft" no longer holds.

Source: libraw.org/node/2228 (checked 2026-07-20)

2-3. dcraw: a permission notice, not a license

dcraw is Dave Coffin's single-file RAW decoder, and it is the starting point for nearly every implementation that followed. It carries no formal open source license. The opening comment of dcraw.c is the terms.

The RESTRICTED scope is narrow: it covers only the functions that process Foveon images, and only since Revision 1.237. All other code "remains free for all uses."

Sources: dcraw.c ($Revision: 1.478 $, $Date: 2018/06/01$, checked 2026-07-20) / dcraw homepage

Note that the latest published revision of dcraw.c dates from June 2018. We found no end-of-life statement from the author, but it is reasonable to treat the project as effectively frozen. There is little reason to adopt dcraw directly in new work today.

LibRaw is derived from dcraw, and its COPYRIGHT states plainly that "LibRaw do not use RESTRICTED code from dcraw.c." Precisely because it excludes the restricted parts, LibRaw can be distributed under LGPL and CDDL without inheriting dcraw's redistribution conditions.

2-4. The WebAssembly trap

If you want to handle RAW in the browser, a WebAssembly port of LibRaw looks like the obvious candidate. Be careful here.

The npm package libraw-wasm declares "license": "ISC" in its manifest, yet we found no license file in the corresponding GitHub repository. A WASM build of LibRaw is a derivative work, and a downstream wrapper cannot relicense LibRaw's code as ISC. The actual terms should be LGPL 2.1 or CDDL 1.0. On top of that, Emscripten output is statically linked, so whether it satisfies the relinking requirement of LGPL 2.1 is not self-evident. CDDL 1.0 looks like the more natural basis, but the package asserts neither.

2-5. Metadata libraries: the license statements inside the project disagree

ExifTool and exiv2 are used for reading and writing metadata rather than decoding RAW. Both have a problem of a particular kind: it is not that the license cannot be determined, but that checking it surfaces an inconsistency.

ExifTool. The repository's LICENSE file is the full text of GPL v3 (it opens with "GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007"). The README, meanwhile, says: "This is free software; you can redistribute it and/or modify it under the same terms as Perl itself (either the Perl Artistic License or GPL)." The same terms as Perl means a choice of the Artistic License or GPL v1 or later, which is not the same thing as shipping the GPL v3 text. This is not something we failed to verify; it is a documented inconsistency within the distribution. Where the exact terms matter, ask the author.

Sources: ExifTool LICENSE / ExifTool README (checked 2026-07-20)

exiv2. The project wiki states "GPLv2.0 only", but the SPDX headers in the source code that actually ships read SPDX-License-Identifier: GPL-2.0-or-later (for example src/image.cpp). The two differ on a substantive point: whether you may elect v3. In practice, the SPDX header in the source you actually received is the one that governs. This article's table therefore does not assert "GPL v2" but follows the source and says GPL-2.0-or-later.

Sources: exiv2 src/image.cpp (SPDX header) / Exiv2/exiv2 repository (checked 2026-07-20)

3. Adobe DNG

DNG (Digital Negative) is Adobe's general-purpose RAW format. It is often simplified to "the spec is public, so it is free," but in practice you have to separate three things: the patent license, the SDK license, and the trademark.

3-1. The patent license

Through the DNG Specification Patent License, Adobe grants "all individuals and organizations the worldwide, royalty-free, nontransferable, nonexclusive right under all Essential Claims to make, have made, use, sell, import, and distribute Compliant Implementations." The scope is limited solely to permitting the reading and writing of image files that comply with the DNG Specification.

Three practical points follow.

• Attribution is required: implementations must state prominently, in source and documentation, that "This product includes DNG technology under license by Adobe."
• Defensive termination: your rights may be revoked if you bring a patent action against Adobe relating to reading or writing DNG-compliant files.
• No specific patent is named: the license does not identify particular patents.

Sources: Adobe: Digital Negative (DNG) / DNG Specification 1.6.0.0 PDF (carries the DNG Specification Patent License up front) (checked 2026-07-20; later editions are linked from the DNG page)

3-2. The DNG SDK

The DNG SDK ships with source code, under a broad grant: a "non-exclusive, worldwide, royalty free license to use, reproduce, prepare derivative works from, publicly display, publicly perform, distribute and sublicense the Software for any purpose." It is nonetheless not an OSI-approved license. Copyright notices must be preserved, documentation may be copied but not modified, and commercial distributors must defend, indemnify and hold harmless Adobe.

Source: Adobe: Digital Negative (DNG) (SDK distribution page) (checked 2026-07-20; clauses cross-checked against the license text bundled with the SDK and public mirrors)

3-3. Trademarks are a separate matter

"Adobe" and the DNG logo are trademarks or registered trademarks of Adobe, and using them to endorse or promote a product requires a separate written agreement with Adobe. The patent license being free has nothing to do with whether you may use the logo.

Source: Adobe: Digital Negative (DNG) (checked 2026-07-20)

3-4. It became an ISO standard in March 2026

For a long time DNG was not an ISO standard. The related TIFF/EP is ISO 12234-2, and DNG has been described as compatible with it, but being compatible is not the same as being identical.

That changed recently. DNG has been published as ISO 12234-4:2026, "Digital imaging — Image storage — Part 4: Digital negative format". The iso.org listing gives only "Edition 1" and "2026-03"; no day-level publication date is shown. This article therefore stays within what can be verified and says March 2026.

Sources: ISO 12234-4:2026 / ISO 12234-2:2001 (TIFF/EP) (checked 2026-07-20)

4. Official camera vendor SDKs

It is tempting to assume that using an official vendor SDK is the safe route, but the SDK's purpose is often not RAW conversion at all. Here is what we were able to confirm.

4-1. Nikon

Nikon's SDK site describes two families: "A Camera Remote SDK to integrate remote control features" and "An Image SDK to open RAW images (NEF and NRW files)." Among the vendors we checked, Nikon stands out for offering an official SDK that opens RAW files. On cost, Nikon states that "the use of SDK is free within the limit of license agreements," and on conditions, that "All limitations you need to follow (if any) are written in the license agreements presented when you download the SDKs." In other words, the agreement presented at download time is what governs. The application flow likewise only lets you proceed once you accept the agreement.

Sources: the quoted passages are all from the Nikon SDK FAQ (/information/en/). The description of the application flow comes from the application guide (both checked 2026-07-20)

4-2. Canon

Canon's EDSDK is provided through an application form. Canon's Asia SDK listing shows "ED-SDK V13.20.10 with RAW Library" and "ED-SDK V13.20.11" as separate entries. The release notes also record that version 13.9.10 (December 13, 2018) "Deleted RAW development functionality."

Sources: Canon Developer Resources / EDSDK release notes (checked 2026-07-20)

4-3. Sony

Sony's Camera Remote SDK is aimed at remote control and retrieval of captured images; no RAW decoding capability is described anywhere on the page. Its license terms are public, and the key points are:

• The grant is "limited, non-exclusive, and non-transferable," covering installing and using the software on your PC.
• Redistribution is allowed only in embedded form: you may "incorporate a binary form of the library file into the APPLICATION SOFTWARE in an inseparable way and distribute."
• You "may not attempt to derive source code, modify, reverse engineer, decompile, or disassemble any of the SOFTWARE."
• A "Prohibited Use" section bars military and weapons applications.

Sources: Sony Camera Remote SDK / license agreement (checked 2026-07-20)

4-4. Fujifilm and Panasonic

Fujifilm's Camera Control SDK exists to automate image transfer and remotely access basic controls, and as noted above, RAF conversion information is explicitly out of scope. The same page also carries a strong clause: "USING THIS SDK TO CONNECT TO, OR CONTROL, ANY COMPATIBLE FUJIFILM CAMERA, WILL VOID THE CAMERA'S LIMITED PRODUCT WARRANTY." That is a consequential line to overlook during evaluation.

Panasonic's LUMIX Remote Control Library covers settings, shooting operations, and acquisition of live view or still and video copies. Using it requires accepting a software license agreement and entering the 11-digit code printed inside the camera's battery holder. The terms also note that operation and support are not guaranteed because it is a beta version.

Sources: FUJIFILM Camera Control SDK / LUMIX SDK (checked 2026-07-20)

5. Where reverse engineering stands

Since there are no published specifications, open source RAW decoders exist because someone analyzed the formats. That raises the question of interoperability exceptions.

5-1. The 2005 NEF encryption controversy

This became a real dispute in 2005, when Nikon encrypted the white balance data in the D2X and D2Hs, leaving third-party converters unable to handle it correctly. Nikon defended the move, saying that "Nikon's preservation of its unique technology in the NEF file is employed as an action that protects the uniqueness of the file," and pointed developers to its official SDK.

At the time, Adobe's Thomas Knoll warned that reverse engineering could mean legal trouble with Nikon through the license agreement or the Digital Millennium Copyright Act of 1998.

Source: Nikon Defends Encrypted NEF Format (checked 2026-07-20)

5-2. Interoperability exceptions

EU: Software Directive 2009/24/EC, Article 6 (Decompilation). Authorization is not required where reproduction or translation of the code is indispensable to obtain the information necessary to achieve interoperability of an independently created program. Three conditions apply: the act must be performed by a licensee or an authorized person; the information must not have been previously readily available; and it must be confined to the parts necessary. Article 6(2) further bars using the information obtained for other goals, giving it to others except as needed for interoperability, or using it to develop a substantially similar program.

Source: Directive 2009/24/EC Article 6 (checked 2026-07-20)

US: DMCA, 17 U.S.C. §1201(f). A person who has lawfully obtained the right to use a copy of a computer program may circumvent an access control measure "for the sole purpose of identifying and analyzing those elements necessary to achieve interoperability of an independently created computer program," limited to elements not previously readily available (§1201(f)(1)). §1201(f)(2) permits developing and using the technological means to do so, and §1201(f)(3) permits sharing the resulting information or means with others solely for the purpose of enabling interoperability. That last provision is the one that matters for shipping an open source RAW decoder.

Source: 17 U.S. Code §1201 (checked 2026-07-20)

6. A practical checklist

When you design a product or service that handles RAW, check at least the following.

1. Ask whether you need RAW decoding at all. If the goal is display or culling, extracting the embedded JPEG may be enough (see below).
2. If you use LibRaw, document which of LGPL 2.1 and CDDL 1.0 you chose, and design for the obligations of that choice: attribution, publishing changes, and the linking model.
3. Check your build configuration for demosaic packs. They bring GPL conditions with them.
4. For WASM packages, do not take the declared license at face value; audit what is actually bundled.
5. If you handle DNG, put the attribution notice in your product's source and documentation. Logo use needs a separate agreement with Adobe.
6. For vendor SDKs, the agreement presented at download is the real document. Have legal review the redistribution, commercial use, and confidentiality clauses before you apply.
7. Some terms, as with Fujifilm, affect the product warranty. Do not skim the notices on the SDK page.

7. What we could not verify

8. The choice we made on this site

Given all of the above, this site does not decode RAW in the browser. Instead, we publish a tool that extracts the JPEG preview embedded in the RAW file. Most cameras generate a JPEG at capture time and store it inside the RAW file, and pulling it out only requires reading JPEG marker structure, with no RAW decoder involved.

What it can do is limited. This is not RAW conversion, so you do not get the real benefit of RAW, such as recovering exposure or white balance after the fact. In exchange, none of the licensing relationships discussed in this article are pulled into our site. We offer it as one worked example of deciding what you actually need and then choosing a design with no dependency.