Extract IPTC metadata from PNG text chunks

[Copilot]

PngMetadataReader silently ignored IPTC data in PNG files. GIMP, ImageMagick, and Photoshop embed IPTC using a hex-encoded "raw profile" format stored in tEXt, zTXt, or iTXt chunks under the keyword Raw profile type iptc.

Changes

• PngMetadataReader: In handlers for all three text chunk types, detect the Raw profile type iptc keyword and route decoded bytes to IptcReader instead of storing as generic text pairs
• decodeRawProfile(): New private helper that parses the raw profile envelope format:

  \n
  iptc\n
        <length>\n
  <hex data, 72 chars/line>\n
  

  Handles Unix, Windows (\r\n), and legacy Mac (\r) line endings. Returns null on malformed input rather than throwing.

Test data added

Three minimal synthetic PNGs — one per chunk type (tEXt, zTXt, iTXt) — each carrying the same IPTC payload (object name, caption, two keywords), with corresponding assertions against IptcDirectory.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• repository.sonatype.org
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --enable-native-access=ALL-UNNAMED -classpath /usr/share/apache-maven-3.9.14/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/usr/share/apache-maven-3.9.14/bin/m2.conf -Dmaven.home=/usr/share/apache-maven-3.9.14 -Dlibrary.jansi.path=/usr/share/apache-maven-3.9.14/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/metadata-extractor/metadata-extractor org.codehaus.plexus.classworlds.launcher.Launcher test -pl . -Dtest=PngMetadataReaderTest -q (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)