ARW to JXL Converter

Encoding: the ARW uses Sony's lossy compressed raw, uncompressed (since the A7R II) or lossless compressed (since the A1); JXL uses lossy VarDCT or lossless modular coding; existing JPEGs can be repacked without loss, and the download is a JPEG XL encoded with libjxl compiled to WebAssembly, lossy at the quality you choose or lossless.

Bit depth: 12 or 14 bits per channel in the ARW; JXL allows 8 to 16 bits per channel, or floating point, and the JXL written here has 8 bits per channel. The sensor's 12 or 14 bits are not used: the 8-bit camera preview is converted.

Colour: camera RGB from a Bayer mosaic in the ARW; JXL supports sRGB, Display P3, linear and other spaces described in the codestream, written here as 8-bit sRGB.

Metadata: the ARW can carry EXIF, Sony maker notes, a thumbnail and a full-size JPEG; JXL can carry EXIF and XMP boxes in the container form, often stripped by encoders, but nothing is copied across.

ARW is the raw format of Sony Alpha, RX and Cyber-shot cameras. It stores the sensor data (compressed, uncompressed or lossless compressed, depending on the model) with a full-size JPEG preview.

ARW is TIFF-based: the first directory carries EXIF and Sony's JPEG preview and the sensor data sits in a sub-directory. In Sony's classic compressed raw each block of 16 same-colour pixels keeps an 11-bit maximum and minimum plus 7-bit steps for the rest, which can leave artefacts beside high-contrast edges.

ARW files usually come from Sony Alpha mirrorless and SLT cameras, RX compacts and some Cyber-shot models.

JPEG XL is a next-generation format designed to replace JPEG. It compresses better than JPEG and WebP, supports lossless, HDR and progressive decoding, and can losslessly repack existing JPEGs.

A JPEG XL file is either a bare codestream starting with FF 0A or an ISO base media container whose 'jxlc' box holds the codestream. A recompressed JPEG keeps a 'jbrd' box that lets the original JPEG bytes be rebuilt exactly.

JXL is the better choice for archiving and future-proof high quality storage, while ARW suits editing Sony photos in a raw developer.

JXL strengths: Excellent lossy and lossless compression; Progressive decoding and HDR; Huge image sizes. Drawbacks to weigh: Browser support is limited (Safari only by default); Few apps can open it yet.