Raw image format (Panasonic)

RW2 is the raw photo format of Panasonic Lumix cameras. Micro Four Thirds bodies such as the G and GH series, the full-frame S series and raw-capable compacts like the LX100 or the TZ/ZS travel zooms all save it. Leica models built by Panasonic, such as the D-Lux and V-Lux, write the same data with the extension RWL. If someone sent you an RW2, it came straight from a Lumix memory card.

History

The first Lumix cameras with raw support saved files with the plain extension .RAW. Around 2008, with models such as the FZ28, LX3 and G1, the first Micro Four Thirds camera ever, Panasonic switched to RW2. The format has stayed in use since, through the GH video cameras and the full-frame S1 and S5 lines launched from 2019. Panasonic does not publish a specification, so third-party support is based on reverse engineering. For Windows 7 Panasonic once offered its own LUMIX RAW Codec. On current Windows this role is taken by Microsoft's Raw Image Extension.

What is special about RW2

• Almost TIFF. The structure is TIFF, but the header reads IIU instead of the standard TIFF marker. Ordinary TIFF readers therefore refuse the file, even though tools such as ExifTool read it without trouble.
• Proprietary compression of the sensor data, 12 bits per pixel on most Micro Four Thirds bodies, 14 bits on the S series and some newer models.
• Full-size JPEG inside. Every RW2 carries a complete JPEG with its own EXIF, which is what thumbnails and quick viewers show.
• Lens corrections as instructions. Micro Four Thirds lenses, and the zoom lenses of Lumix compacts, are designed on the assumption that software straightens their distortion. The RW2 does not contain a corrected image. It contains the parameters for the correction. Lightroom and SILKYPIX apply them automatically, tools that ignore them show the raw geometry: barrel distortion and dark corners at the wide end, sometimes a slightly wider view than the camera JPEG.
• High Resolution mode (G9, S1R, S5 II and others): the camera combines several shifted exposures into one large RW2. The file can be several times the normal size.

How to open RW2 files

• SILKYPIX Developer Studio SE (Windows, macOS) is free for Lumix owners from Panasonic's support site and reproduces the camera's Photo Styles.
• Windows 10 and 11: install the Raw Image Extension from the Microsoft Store. The Photos app and File Explorer then handle RW2.
• macOS and iOS: Preview and Photos read RW2 from supported models.
• Linux: darktable, RawTherapee, and for quick browsing any viewer that shows the embedded JPEG.
• Lightroom and Photoshop via Camera Raw.

Common RW2 problems

RW2 won't open on Windows

Without an extension, Windows has no decoder for RW2. Install the Raw Image Extension. If a brand-new camera is still not recognised, the extension has not caught up yet. SILKYPIX or an up-to-date Lightroom will help in the meantime.

RW2 not supported in Photoshop

Camera Raw is older than the camera. Update it, or convert the files to DNG with the free Adobe DNG Converter.

Photo looks distorted or has dark corners

The program has not applied the embedded lens corrections. Turn on lens correction for your lens profile, or use software that reads the correction data from the file.

Converting RW2

RW2 is usually converted to JPG for sharing and printing and to TIFF for further editing. Our converter decodes RW2 with camera white balance, standard demosaicing, sRGB, 8 bits per channel, full sensor area. The embedded lens corrections are not applied, so wide-angle shots may show distortion and vignetting that the camera JPEG did not have. Photo Styles and noise reduction are not applied, and full EXIF is not copied. High Resolution files can exceed our 100 MB upload limit. The general behaviour of raw conversion is described on CR2 to JPG. Related: older Lumix RAW files, ORF from Olympus/OM System, the other big Micro Four Thirds brand.

Quick facts

Further reading: Camera raw formats at the Library of Congress, RW2 structure documented by libopenraw.