Gianni Rosato's Case Against JPEG XL: Roughly 10x Slower Decode Than WebP and a 17-Second Crafted-Image DoS

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Rosato's September 13 post argues JPEG XL should not ship in browsers, citing CVVDP, MS-SSIM and SSIMULACRA2 results where other encoders win on both speed and fidelity, plus missing directional prediction modes, no deblocking loop filter leaving persistent mosquito noise, and an XYB colorspace that does not deliver its advertised gains. The concrete numbers: decode takes roughly 10x longer than WebP at comparable file size, and the format's expressivity permits crafted images that consume 17+ seconds to decode on modern hardware, a denial-of-service surface for any site accepting user uploads. It reached 201 points and 271 comments in 12 hours.