Dropbox Open Sources New Lossless Middle-Out Image Compression Algorithm (dropbox.com)

Dropbox announced on Thursday that it is releasing its image compression algorithm dubbed Lepton under an Apache open-source license on GitHub. Lepton, the company writes, can both compress and decompress files, and for the latter, it can work while streaming. Lepton offers a 22% savings reductions for existing JPEG images, and preserves the original file bit-for-bit perfectly. It compresses JPEG files at a rate of 5MB/s and decodes them back to the original bit at 15MB/s. The company says it has used Lepton to encode 16 billion images saved to Dropbox, and continues to utilize the technology to recode its older images. You can find more technical details here.

Comments

Re:Regardless of CPU clock speed?

[retchdog]

PR? The code is on github, and imho a very nice accessible explanation of their algorithm is in the linked article. They developed some neat software to save money by essentially modernizing JPEG to compress beyond the 8x8 blocks it was designed to use and, having done that, are now letting other people use it too. What is with your crabby, paranoid attitude? Instead of being an asshole, you could just, you know, build the code yourself and experiment with it, rather than sneering at a gift horse. This is exactly the use case for open source software.

Although I would prefer if they explained the sampling methodology for their images, they do present a few simple scatterplots of (de-)compression performance as a function of original JPEG file size. It's not as in-depth as xiph.org foundation's stuff, but it's a hell of a lot more than a PR piece.