Not just that, but the Exif orientation can be used to do the lossless rotation nowadays. (It's really the postprocessing step, but that step is now widely impl

Not just that, but the Exif orientation can be used to do the lossless rotation nowadays. (It's really the postprocessing step, but that step is now widely implemented.) This approach has no MCU limitation and even is honored by JPEG XL. > Best guess at what the author saw, the original files were likely originally compressed with an encoder that did not optimize the huffman table, and his newer tools likely do compute an optimal huffman table for compressing the DCT coefficients, that and the fact that the author was doing a lossy recompression would often result in file size reductions. `jpegtran -optimize` or any other optimizer (I tried ECT in particular) didn't work much for this particular image, so the Huffman table should have been almost optimal. Probably it has very low quantization factors instead.