01

Important PNG chunks

IHDR defines dimensions and color type, IDAT stores compressed pixels and IEND closes the stream. Ancillary chunks can add metadata, profiles and animation.

Key points
  • eXIf: EXIF payload
  • tEXt/zTXt/iTXt: textual metadata
  • iCCP/sRGB/gAMA/cHRM: color behavior
  • acTL/fcTL/fdAT: APNG animation
02

Safe processing

Validate chunk sizes and CRCs, never inject text metadata as HTML, and keep animation and color chunks unless the user explicitly requests a different transformation.

What this does not prove

A metadata result describes the fields and structures that the supported parser could read. It does not, by itself, prove authenticity, intent, authorship or the truth of the visible scene.

Sources