readIptc

(no submodules)

Purpose

Parses IPTC IIM (Information Interchange Model) metadata from a Photoshop 3.0 APP13 JPEG segment payload. IPTC is the editorial metadata standard used by news agencies and photo distributors for fields such as headline, caption, copyright, keywords, and geographic information. The parser traverses the Photoshop 8BIM resource block structure to locate the IPTC-NAA data block (resource ID 0x0404) and then iterates its Record 2 datasets.

Features

Parses the Photoshop 3.0 + 8BIM wrapper before accessing IPTC data
Extracts all standard Record 2 editorial fields: headline, caption, copyright, creator, keywords, city, country code, country name, source
Handles repeatable fields (keywords) correctly as arrays
Returns an empty object gracefully if no IPTC data is present
Zero external dependencies — pure TypeScript byte-level parsing

Usage: Basic Example

import { readIptc } from "@suaveplan/exif/iptc";

const iptc = readIptc(app13SegmentData);
console.log(iptc.headline);
console.log(iptc.keywords); // string[]

Usage: Advanced Example

import { parseJpegSegments, isIptcSegment } from "@suaveplan/exif";
import { readIptc } from "@suaveplan/exif/iptc";

const segments = parseJpegSegments(jpegBuffer);
const iptcSeg = segments.find(isIptcSegment);

if (iptcSeg) {
  const iptc = readIptc(iptcSeg.data);
  console.log("Headline:", iptc.headline);
  console.log("Copyright:", iptc.copyright);
  console.log("Creator:", iptc.creator);
  console.log("Keywords:", iptc.keywords?.join(", "));
  console.log("Location:", [iptc.city, iptc.country].filter(Boolean).join(", "));
}

API Reference

`readIptc(data: Uint8Array): IptcData`

Parses IPTC data from a raw APP13 segment payload (the full data field of a JpegSegment with marker 0xFFED).

Returns: IptcData object with all recognisable fields populated, or an empty {} if the data does not match the Photoshop 3.0 + 8BIM + IPTC structure.

Does not throw. Malformed or truncated data results in partial or empty output.

Dataset mapping

Dataset code	IptcData field
Record 2, DS 5 (0x05)	`headline`
Record 2, DS 80 (0x50)	`creator`
Record 2, DS 120 (0x78)	`caption`
Record 2, DS 25 (0x19)	`keywords[]`
Record 2, DS 90 (0x5A)	`city`
Record 2, DS 100 (0x64)	`countryCode`
Record 2, DS 101 (0x65)	`country`
Record 2, DS 116 (0x74)	`copyright`
Record 2, DS 115 (0x73)	`source`

Implementation Notes

The Photoshop 3.0 wrapper uses Pascal strings for resource names (1-byte length followed by the name, padded to an even byte boundary). The 8BIM block iteration stops on the first non-8BIM signature to avoid reading into compressed image data. IPTC record markers are 0x1C followed by record number and dataset number. Only Record 2 (Application Record) datasets are extracted; Record 1 (Envelope Record) envelope fields are skipped. The string decoder uses Latin-1 (one byte per character); IPTC IIM data is specified as 7-bit ASCII.

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