png.h File Reference

Portable Network Graphics codec. More...

#include "tinyimg/codec/codec.h"

Go to the source code of this file.

Variables
const TinyCodec	tiny_codec_png
	The PNG codec.

Detailed Description

Portable Network Graphics codec.

Author

Gregory Mitchell (me@gm.nosp@m.itch.nosp@m.215.x.nosp@m.yz)

Version

1.0.0

Date

2026-09-02

Copyright

Copyright (c) 2026

Variable Documentation

tiny_codec_png

const TinyCodec tiny_codec_png

extern

The PNG codec.

Decodes every color type at every bit depth the format defines: grayscale and palette at 1, 2, 4 and 8 bits, truecolor at 8 and 16, either of the latter with an alpha channel, and palette or grayscale transparency through tRNS. Sixteen bit samples are reduced to eight by taking the high byte, which is what every viewer does. Encodes 8 bit grayscale, grayscale with alpha, truecolor and truecolor with alpha, choosing a row filter per row by the minimum sum of absolute differences and compressing with the shared DEFLATE unit.

A non-interlaced image is unfiltered one row at a time, so a region decode holds the region plus two scanlines rather than the whole image, and stops reading once it is past the region's last row. An Adam7 image cannot work that way: its rows arrive spread across seven passes, so the whole plane is assembled first and the region taken afterwards.

Every chunk's CRC-32 is checked. A stream whose compressed data is split across many IDAT chunks is joined before inflating, which a decoder that inflated each chunk on its own would read as corrupt.