PhotoView

The standards behind your photo’s metadata

Updated on October 30, 2026

Every photo carries a small diary. It notes when it was taken, with which camera, at which settings, and often where. Add a caption, a few keywords, a star rating or a copyright notice, and the diary grows. None of that would survive the trip from camera to phone to computer if every device and every app wrote it in its own way. A handful of standards, some of them older than most digital cameras, keep those details readable wherever a photo goes.

This page walks through the standards behind the fields PhotoView shows, in the order they appeared. The first part is the short version, in case you just want an impression of the standards behind photo metadata or a grip on terms used in PhotoView such as EXIF, IPTC and XMP. The second part goes into more detail and provides links to the standards themselves and to further information, for everyone who wants to dig deeper.

One thing up front: PhotoView does not take photo files apart itself. It reads their metadata through Apple’s own frameworks: ImageIO, the part of iOS, iPadOS and macOS that reads image files, along with PhotoKit for the photo library and AVFoundation for videos. PhotoView shows what these frameworks read, so a new version of a standard reaches PhotoView only once Apple’s frameworks support it. The current versions named below are the newest editions of the standards, not necessarily the ones PhotoView can show. Each section says where PhotoView stands.

Metadata standards: the short version

What will probably be of interest to you if you are:

In detail

Each section answers the same questions: who wrote the standard and why, what is in it, what it means for you, what PhotoView shows of it, and where to find the standard itself.

TIFF (1986)

Who and when. TIFF, the Tagged Image File Format, was created at Aldus Corporation, the company behind the desktop publishing program PageMaker, together with Microsoft. The first specification appeared in autumn 1986. Aldus was a software company, not a standards body, and its motive was a practical one: in the mid-1980s every desktop scanner wrote its own format, and TIFF was meant to replace them with one. Adobe acquired Aldus in 1994 and has looked after TIFF ever since.

What’s inside. A TIFF file is a list of numbered tags, each holding one piece of information: width, height, compression and color, plus descriptive tags such as the camera make and model, the software, the date, the artist and a copyright notice. New tags can be added without breaking older readers. That idea turned out to be TIFF’s lasting gift. EXIF stores its data in the same tag structure (the EXIF block in a JPEG is essentially a small TIFF file inside the JPEG), and DNG is an extension of TIFF. The last revision, TIFF 6.0 from June 3, 1992, is still the current one.

What it means for you.

In PhotoView. ImageIO reads the TIFF tags, and PhotoView shows them as Make, Model, Software, Artist, Host computer, Orientation and DPI. Copyright and Description in the Description group can come from TIFF tags as well.

Links.

IPTC (1991)

Who and when. The International Press Telecommunications Council was founded in London in 1965. Its more than 60 members are news agencies, publishers and the companies that build their software, and its mission is to simplify the distribution of information. Its standards describe how news stories, photos and their descriptions move between agencies and newsrooms.

In 1990, IPTC and the Newspaper Association of America started work on the Information Interchange Model (IIM). Version 1 was approved in 1991: a way to wrap any news item, text, photo or graphic, in an envelope with its caption, category, dateline and credits. Adobe took a subset of these fields and stored them in Photoshop, JPEG and TIFF files. Other software followed, and millions of photos were captioned this way. That is why the caption, keywords and copyright notice in a photo file are still called “IPTC” today. IIM itself has been frozen since 1997.

Two steps brought it into the present. In 2004, IPTC and Adobe re-expressed the IIM fields in XMP as IPTC Core, fully backwards-compatible. In 2008, the IPTC Extension added much more detail. Since then both are published together as the IPTC Photo Metadata Standard, updated almost every year.

What it is for. EXIF records how a photo was taken. IPTC records what it shows, who made it and how it may be used. It was written for news and stock photography, which is why it cares so much about credit and rights.

What’s inside.

Recent versions follow current questions. Alt text and an extended description for accessibility arrived in 2021. A data-mining field from 2023 states whether a photo may be used for AI training. The digital source type, around since 2009, tells a camera capture from a composite or an AI-generated picture. And since November 2025 (version 2025.1), four more fields record which AI system made a picture, its version, the prompt and who wrote it.

What it means for you.

In PhotoView. ImageIO reads the IIM block and the XMP that carries IPTC Core and Extension, and PhotoView shows the fields it knows from them. The IPTC group holds the IIM and IPTC Core fields, the IPTC Extension group the newer fields, including licensing and the AI details of version 2025.1. Headline, caption, keywords, creator and copyright also appear under Description. All of them are part of PhotoView Pro.

Links.

ICC profiles (1994)

Who and when. The International Color Consortium was formed in 1993 by eight companies: Adobe, Agfa, Apple, Kodak, Microsoft, Silicon Graphics, Sun Microsystems and Taligent. Its purpose is to promote open, vendor-neutral color management that works across platforms. The first profile specification followed in June 1994.

What it is for. The numbers in a photo file only describe colors once you know which “dialect” they are written in. An ICC profile is that key: it describes a color space or a device (a camera, a screen, a printer) in relation to a common, device-independent reference. With the profile embedded, an app can translate the colors so a photo looks the same on any calibrated screen and in print.

What’s inside. A header and a set of tags: the reference the profile is built on, plus the primary colors, white point and tone curves of a color space, or look-up tables for more complex devices. The current specification, ICC.1:2022 (profile version 4.4), was amended in April 2025. For special needs such as spectral data there is a second, more flexible architecture called iccMAX.

What it means for you.

In PhotoView. Color profile shows the name of the embedded profile as ImageIO reports it, next to Color space and Color model in the Image group.

Links.

EXIF (1995)

Who and when. EXIF, the Exchangeable Image File Format (the standard itself writes it “Exif”), was first defined in October 1995 by JEIDA, the Japan Electronic Industry Development Association, just as digital cameras reached consumers. Later versions came from JEITA, the Japan Electronics and Information Technology Industries Association, and since version 2.3 in 2010, JEITA and CIPA maintain it together.

CIPA, the Camera & Imaging Products Association, was set up in July 2002 as the successor of the Japan Camera Industry Association. Its regular members are the camera makers, Canon, Nikon, Sony, Fujifilm, Panasonic and others, with companies such as Adobe, Apple and Microsoft as supporting members. It deals with what cameras and related products need in order to work together, and it publishes the standards and guidelines behind that.

What it is for. One shared way for a camera to write down how a photo was made, inside the photo file, so any computer, phone or app can read it.

What’s inside.

EXIF uses TIFF’s tag structure and travels as an embedded block in JPEG and HEIC files. Version 3.0 (May 2023) allowed UTF-8 text, so names and descriptions can use any script. Version 3.1 followed on January 30, 2026 with seven new tags. A companion standard, CIPA DC-010, defines how EXIF fields are written in XMP.

A neighbor from the same family: DCF, the Design rule for Camera File system, is the reason cameras store photos in a folder called DCIM, with names like IMG_0001.JPG.

What it means for you.

In PhotoView. The Date & time, Camera, Lens, Exposure and Image groups are mostly EXIF, and they are free, as are the Apple maker notes. The Location group with the map link shows the GPS data, and like the Canon and Nikon maker notes it is part of PhotoView Pro. PhotoView reads all of this through Apple’s ImageIO, which today covers EXIF up to version 2.32. What versions 3.0 and 3.1 added, such as the photographer, the image title or the AI opt-out, does not show up in PhotoView, and neither does text stored in the UTF-8 format that 3.0 introduced.

Links.

XMP (2001)

Who and when. Adobe introduced the Extensible Metadata Platform in April 2001 with Acrobat 5.0. Again a software company and not a standards body, but Adobe opened XMP up: in 2012 its core became an international standard, ISO 16684-1, revised in 2019. ISO, the International Organization for Standardization, has brought experts together since 1946 to agree on common ways of doing things. Its 177 members are national standards bodies, one per country. Selling its standards pays for that work, which is why ISO documents are not available for free.

What it is for. EXIF and IIM have fixed lists of fields. XMP is a container for any metadata: anyone can define a vocabulary (a “namespace”) and store it next to the others, in a form every XMP reader can parse. It can be embedded in JPEG, TIFF, PNG, PDF, DNG, MP4, MOV and many other file formats. For files that should never change, like most RAW files, the same data goes into a sidecar: a small .xmp file with the same name, right next to the photo.

What’s inside. The ISO part defines the data model, how it is written as XML, and a set of core properties: title, description, creator, rights, rating, the application that wrote the file, dates and an edit history. How XMP is embedded in each file format, and how sidecars work, is described in Adobe’s own specification (part 3). On top of that sit the vocabularies others have defined: IPTC Core and Extension, EXIF in XMP, and those of the editors themselves, such as Lightroom’s hierarchical keywords and Camera Raw’s develop settings, DJI’s drone data or Google’s panorama fields.

Because the same detail can live in EXIF, in IIM and in XMP, the copies can disagree. Adobe, Apple, Canon, Microsoft and Nokia formed the Metadata Working Group in 2006, Sony joined later, to write down how apps should keep them in sync. Its guidelines, version 2.0 from 2010, are still the reference. How PhotoView decides between the sources is described in Sidecars and RAW: the .xmp next to your file.

What it means for you.

In PhotoView. ImageIO reads the XMP embedded in a photo on iPhone, iPad and Mac, and on a Mac also the .xmp sidecar PhotoView finds next to a file opened from disk. The XMP and IPTC Extension groups (PhotoView Pro) show the properties PhotoView knows from the vocabularies named above.

Links.

DNG (2004)

Who and when. Adobe published the Digital Negative on September 27, 2004. It builds on TIFF/EP, an ISO format for camera images from 2001 (ISO 12234-2), which in turn extends TIFF 6.0. In March 2026 DNG became an ISO standard of its own: ISO 12234-4, from ISO’s committee for photography.

What it is for. Camera makers each have their own raw formats, often several, and their specifications are not public. That makes raw files hard to move between apps and risky as an archive. DNG is a publicly documented raw format that anyone may read and write, under a royalty-free license from Adobe.

What’s inside. The raw sensor data, plus what a raw converter needs to turn it into a photo: color calibration for two light sources, black and white levels, baseline exposure, noise and sharpness, lens corrections, an embedded preview and, if wanted, the original raw file. EXIF and XMP metadata sit in the same file, so a rating or keyword can be written straight into a DNG, without a sidecar. Version 1.7 (June 2023) added JPEG XL compression, and 1.7.1.0 from September 2023 is the current Adobe specification.

Who writes it. Leica, Pentax and Hasselblad cameras, many DJI drones, high-end Samsung phones since the Galaxy S6, and Apple ProRAW on the iPhone 12 Pro and later Pro models. Adobe’s free DNG Converter turns other raw files into DNG.

What it means for you.

In PhotoView. The DNG group (PhotoView Pro) shows the DNG tags ImageIO reads: the DNG version, the camera model and profile, black and white levels, the baseline values, the name of the original raw file and more. Calibration tables and color matrices are left out on purpose: they are meant for raw converters, not for human readers.

Links.

Not on this list

JPEG, HEIF (the HEIC files from an iPhone) and QuickTime (MOV) are file formats: they carry the metadata described here rather than define it. Video files have their own metadata, which PhotoView reads through Apple’s AVFoundation and shows in its Video group. Both would be a story of their own.

Sources

General

TIFF

IPTC

ICC

EXIF

XMP

DNG