The Metadata in PNG files¶

1. PNG File Structure.¶

The Portable Network Graphics (PNG) is a raster graphics file format that supports a portable, legally unencumbered, well-compressed, well-specified standard for lossless bitmapped image files.

A PNG always starts with an 8-byte signature: 137 80 78 71 13 10 26 10 (decimal values).
The remainder of the file consists a series of chunks beginning with an IHDR chunk and ending with an IEND chunk.