The author discusses the minimum required elements of the PNG image format, specifically focusing on the smallest possible PNG file. They point out that the smallest PNG file is 67 bytes and consists of a single black pixel. However, they also mention that there are several other valid 67-byte PNGs that exploit the fact that you can’t have less than one byte of pixel data. The author then delves into the compression step used in PNG files, highlighting the limitations and possibilities of compression algorithms. They explore the possibility of using overlapping backreferences in the compression process and conclude by presenting a 2064-pixel PNG file as an example. Overall, the author provides an interesting and in-depth analysis of PNG compression.
https://belkadan.com/blog/2024/01/The-Biggest-Smallest-PNG/