🍈 Zettelkasten

Portable Network Graphics

1 min read

A Structured Object File Format for images.

File Format

CRLF Signatures

8-byte signature: 89504e470d0a1a0a

  • 89: Detect transmission system that do not support 8-bit data
  • 50 4e 47 : PNG magic number
  • 0D 0A : DOS-style CRLF
  • 1A : byte that stops display of file when DOS command DOS type is used
  • 0A : Unix style LF to detect unix-DOS line end conversion
Extra
  • Header Length (4-bytes) (often 13)
  • IHDR (4-bytes)
  • Width (4-bytes)
  • Height (4-bytes)
  • Bit-depth flag (1-byte)
  • Color-type flag (1-byte)
  • Compression flag (1-byte)
  • Filter flag (1-byte)
  • Interlacing flag (1-byte)
  • CRC (4-byte)

Chunks

  • Chunk length (4-bytes)
  • Chunk Type (4-bytes)
    • IDAT (data)
    • IEND (final chunk)
  • Chunk data
  • CRC (4-byte)

Graph View

Backlinks