> It's also worth noting that it is easy to beat the old formats all-round with off-the-shelf parts, both JPEG and PNG can be bested by changing the outer level

> It's also worth noting that it is easy to beat the old formats all-round with off-the-shelf parts, both JPEG and PNG can be bested by changing the outer level of compression for something that was invented after the formats were made. The heart of JPEG is in The DCT and its energy compaction properties. One crazy thing about the DCT is that it doesn't just let you make trade-offs for high/low frequency features. It also lets you make tradeoffs for horizontal and vertical features. If you customize your quantization matrix to your specific application, you can potentially achieve compression ratios far exceeding anything available today - even if you leave in the crusty old RLE+Huffman coding. If you want to get up to your elbows in this sort of thing, there is an entire book on it by Rao & Yip that is about as comprehensive as it gets - https://www.abebooks.com/products/isbn/9780125802031/31198865463 https://www.abebooks.com/products/isbn/9780125802031/3119886...