JXL to NEF Converter

Encoding: the JXL uses lossy VarDCT or lossless modular coding; existing JPEGs can be repacked without loss; NEF uses uncompressed, lossless compressed, lossy compressed, or High Efficiency on recent Z bodies, and the download is a Linear DNG: demosaiced 8-bit RGB with the colour matrices raw editors need.

Bit depth: 8 to 16 bits per channel, or floating point in the JXL; NEF allows 12 or 14 bits per channel, and the DNG written here has 8 bits per channel, linearised. High-bit-depth JPEG XL files are reduced to 8 bits per channel.

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

Transparency: the JXL stores it as an extra channel in the codestream; the DNG has none, so transparent areas are filled with the colour you choose.

Animation: frames inside a single codestream; the DNG holds one image, so only the first frame is converted.

Metadata: the JXL can carry EXIF and XMP boxes in the container form, often stripped by encoders; NEF can carry EXIF and Nikon maker notes, partly encrypted, plus a thumbnail and a larger preview, but nothing is copied across.

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 files usually come from image editors, archival pipelines and lossless JPEG recompression.

NEF is the raw format of Nikon cameras, from the D1 to the current Z series. It stores 12 or 14-bit sensor data, uncompressed or compressed, with a JPEG preview the camera renders using its Picture Control.

NEF is TIFF-based: the first directory usually holds a small thumbnail, and sub-directories hold the sensor data and, on current bodies, a full-size JPEG preview. Nikon's maker notes are a TIFF structure of their own, and since the D2X their white-balance block is encrypted with a key derived from the camera's serial number and shutter count.

NEF files come from Nikon DSLRs (D-series) and Z-series mirrorless cameras.

Forms and workflows that ask for NEF usually feed a raw editor, and each of those opens DNG as well, so the DNG can take the NEF's place. Keep the JXL if you only need to view or share the picture.

What NEF offers when it comes straight from the camera: Lossless compressed mode with no data loss; Picture Control recorded so Nikon NX Studio can reapply it; 12 or 14-bit sensor data. Its drawbacks: Partly encrypted maker notes; The lossy compressed mode discards some sensor data; Large files on high-resolution Z bodies.