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00:00 Intro
03:45 Parse PNG structure
22:18 Parse the header
27:00 Find the data
47:00 Visualize data
56:00 Apply PNG filters
01:18:33 New color type, new problem
01:33:50 Glance at color profiles

sphaerophoria

A live coding session implementing a PNG decoder from scratch in Zig. The developer parses PNG file structure (chunks, headers), implements decompression using zlib, handles filter algorithms (none, sub, up, paeth), and works through color type support (RGB, RGBA). The motivation is extracting embedded color profiles for a custom image viewer used to adjust game brightness. The implementation handles chunk parsing, data decompression, scan line filtering, and validates output by writing to PPM format.

Speed running writing a PNG reader