Metadata Model

exiftool-ts normalizes tags across all formats into one flat record of TagValues, matching ExifTool's tag names and printed representations.

Tag Record

read() returns a FileInfo:

interface FileInfo {
  path: string;                     // Source path
  format: string;                   // Detected format ("JPEG", "DNG", …)
  tags: Record<string, TagValue>;   // Flat tag map, ExifTool naming
  errors?: string[];
  warnings?: string[];
}

type TagValue = string | number | boolean | Uint8Array | null | TagValue[];

There is no nested tag object and no raw/groups fields — one key per tag, ExifTool's name (e.g. ExposureTime, GPSLatitude, ImageSize).

Tag Groups

Groups exist for output formatting (CLI -G[NUM], -g[NUM]) and are resolved from the tag database's group families:

Group	Standards	Description
EXIF (IFD0, ExifIFD)	Exif 2.3+, TIFF/EP	Camera settings, image properties
GPS	GPS IFD	Geolocation data
XMP	XMP Core, IPTC Core, Dublin Core	Extensible metadata
IPTC	IIM, IPTC Core	News/photo agency metadata
ICC	ICC Profile	Color management
JFIF	JPEG File Interchange Format	JPEG stream header
Composite	Computed	Derived tags
File	File system	File properties
MakerNotes	Vendor-specific	Core 6 vendors decoded (Canon, Nikon, Sony, Olympus, Panasonic, Pentax); others keep markers

With -G1 the CLI prefixes tags (EXIF:ExposureTime, Composite:Aperture). The library API returns unprefixed names.

Value Representations

Values mirror what ExifTool prints — exiftool is the ground truth:

Kind	Representation	Example
Strings	plain string	Make: "Canon"
Numbers	number where ExifTool prints one	FNumber: 2.8
PrintConv'd enums	string	Orientation: "Horizontal (normal)"
Rationals/fractions	string	ExposureTime: "1/125"
Dates	ExifTool date string (YYYY:MM:DD HH:MM:SS±HH:MM)	ModifyDate: "2024:09:17 21:46:07+02:00"
GPS coordinates	DMS string, or decimal with -c %.6f	45 deg 11' 15.24" N
Arrays	TagValue[]	Keywords: ["nature", "landscape"]
Binary	Uint8Array (placeholder string in JSON unless -b)	ThumbnailImage

Composite Tags

Computed from multiple source tags (computeCompositeTags), same names and values as ExifTool:

Composite Tag	Sources
Aperture	FNumber
ShutterSpeed	ExposureTime
ImageSize	ImageWidth, ImageLength/Height
Megapixels	ImageWidth, ImageHeight
GPSPosition	GPSLatitude, GPSLongitude
LensID / Lens	LensModel / makernote lookups (partial vendor coverage)
SubSecCreateDate	ModifyDate/OffsetTime/SubSecTime
LightValue, DOF, HyperfocalDistance, FocalLength35efl	exposure + focal geometry

Accessing Tags

const result = await exiftool.read('photo.jpg');

result.format;                    // "JPEG"
result.tags['Make'];              // "Canon"
result.tags['ExposureTime'];      // "1/125"
result.tags['ImageSize'];         // "8256x5504"
Object.keys(result.tags);         // every tag name

Group-prefixed views are a CLI/output concern (-G1 -j), not part of FileInfo.