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Image Codecs
JPEG, PNG, WebP, AVIF — the DCT, quantization, and lossless pipelines
01
·Image Codecs·★ MEMBER·9 min read
Why JPEG Degrades — The DCT and Quantization from Scratch
When a photo shrinks to a tenth of its size, what exactly was thrown away? Colour conversion, 8×8 blocks, the DCT, the quantization table and the zigzag scan — followed by what the number in "quality 90" really is, and where blocking and mosquito noise are born. Ending with the decisions people who ship images actually make.
02
·Image Codecs·FREE·8 min read
Why PNG Does Not Degrade — Prediction Filters and Deflate
What it means to shrink a file without changing a single bit. Starting from why no compressor can shrink everything, then PNG's five row filters as prediction-and-residual, Deflate (LZ77 plus Huffman), and why photographs resist it while screenshots collapse. Ending with a decision procedure for choosing between PNG and JPEG.
03
·Image Codecs·★ MEMBER·10 min read
WebP, AVIF, JPEG XL — The Image Codec Changing of the Guard
Three successors clearly beat JPEG on efficiency, and the web is still full of JPEGs. This piece traces where each newcomer came from, why still-image codecs keep getting born out of video codecs, and the structural reason a lingua franca doesn't die just because something faster shows up — down to how you actually compare codecs and ship the files.