Error Bounds for HDR Image Coding with JPEG XT
ISO recently published a new image compression standard, JPEG XT, which extends the popular JPEG standard towards higher dynamic range, compression of alpha channels and lossless coding. In part 7 ofJPEG XT, a two-layer lossy image compression for HDR images isintroduced that reconstructs HDR signals by the combination of a baselayer following the legacy JPEG standard, and an extension layer thatenlarges the dynamic range to that of the original image. While bothbase and extension layer are entropy coded by the mechanisms specifiedin the legacy JPEG standard, only the base layer is visible to legacyJPEG decoders. The original JPEG standard now enforces in its part 2error bounds conforming implementations shall satisfy. The questionanswered in this article is in how far these error bounds carry overto error bounds of JPEG~XT for coding of HDR image signals.