The MRW file (.mrw)

MRW is the raw image format of Minolta's digital cameras, and later of Konica Minolta's, after the two companies merged in 2003. When a camera was set to RAW, it saved an MRW file: the values read from the sensor, plus the settings and metadata needed to turn them into a picture later on a computer.

Three groups of cameras wrote it: the DiMAGE 5 and DiMAGE 7 series of bridge cameras, the DiMAGE A1, A2 and A200, and the two digital SLRs, the 7D and 5D. The SLRs were sold under three names depending on the region: Dynax in Europe, Maxxum in the United States and Alpha in Japan, so a Dynax 5D, a Maxxum 5D and an Alpha Sweet Digital are the same camera and write the same files.

No camera has written MRW since 2006 (see below), so the format is frozen. That makes it one of the better-supported old raw formats: every major raw converter learned it years ago, and there are no new variants to catch up with.

A camera sensor doesn't see colour. Each photosite sits under a red, green or blue filter, arranged in a Bayer pattern, and records one brightness value. Making a normal picture from that takes several steps, and a JPEG camera does them all before saving:

1. 1Demosaicing: estimating the two missing colours at every pixel from its neighbours.
2. 2White balance: scaling the channels so that grey looks grey under that light. The MRW stores the camera's chosen multipliers in its WBG block.
3. 3Colour conversion: from the sensor's own colour response to a standard space such as sRGB.
4. 4Tone curve, contrast and sharpening: the camera's picture style, recorded in the RIF block.
5. 5Compression to 8-bit JPEG, which throws away detail you can't recover.

An MRW stops before all of that. The values are linear and keep the full bit depth of the sensor, so you can change white balance and exposure afterwards without the banding or clipping you'd get editing a JPEG. Opened without processing, though, the data looks dark, flat and green-tinted, because there are twice as many green photosites and nothing has applied a curve yet. Raw converters apply defaults when they open the file, which is why the first view can differ from the JPEG the camera showed.

On 19 January 2006 Konica Minolta announced that it would leave the camera and photo business entirely, film included. Its camera business ended on 31 March 2006, apart from digital SLRs and lenses it was making for Sony. On the same date Sony received the assets needed to develop and build digital SLRs for the Minolta lens mount, and from 1 April 2006 Sony took over customer service for Konica Minolta cameras.

Sony's SLRs that followed kept the lens mount but not the file format: Sony cameras save raw photos as ARW. ExifTool's documentation notes that some ARW files carry a little-endian copy of the MRW blocks inside, a visible trace of the shared history.

• Adobe Camera Raw, Lightroom and Lightroom Classic: read MRW directly. Adobe has supported the format for a long time: Camera Raw 3.2, in 2005, added the Dynax/Maxxum 5D.
• macOS and iOS: Apple's current list of supported raw cameras still includes the DiMAGE A1, A2 and A200 and the 5D and 7D under all their names (but not the older DiMAGE 5 and 7), so Photos and Preview open their files.
• Windows: the Photos app shows MRW files once Microsoft's free Raw Image Extension is installed. It's built on LibRaw, whose camera list includes every MRW model.
• Free converters: darktable and RawTherapee open MRW files on Windows, macOS and Linux, with full control over white balance and exposure.
• The original software: the programs Konica Minolta shipped with the cameras haven't been updated since 2006 and may not run on current systems. You don't need them.

# show the camera, settings and date
exiftool photo.mrw

# pull out the embedded preview JPEG, if there is one
exiftool -b -PreviewImage photo.mrw > preview.jpg

# full conversion with darktable's command-line tool
darktable-cli photo.mrw photo.jpg

For an archive, Adobe's free DNG Converter turns MRW files into DNG, an openly documented raw format that keeps the sensor data. Many photographers keep both the MRW originals and the DNG copies.

• Double-clicking does nothing useful. On Windows, install the Raw Image Extension, or open the file from inside a raw converter. Browsers and most image viewers don't decode raw files.
• It shows a small, blurry picture. The viewer found the embedded preview and showed that instead of decoding the raw data. Open it in a raw converter for the full resolution.
• Colours or contrast differ from the camera's JPEG. The RIF block holds the camera's picture style, and third-party converters apply their own defaults instead. Adjust white balance and the tone curve, or start from a camera profile if your converter has one.
• Wrong or swapped colours from one camera only. Software that assumes every MRW has the same Bayer order gets the DiMAGE A200 wrong. Use a current version of your converter.
• Files recovered from an old memory card don't open. Recovery tools find MRW files by their \0MRM signature, but a file cut short loses the end of the image data. Check the size against other files from the same camera: MRW files from one model are all about the same size, because the data isn't compressed.

MRW files can't run code, but their TTW block carries the same Exif data as a JPEG: camera model, firmware, date and time, exposure settings, and maker notes with further camera details. These cameras had no built-in GPS, so location is normally absent unless software added it later. To see everything, run exiftool -a -G1 photo.mrw. If you share a picture publicly, export a JPEG from it and check that file's metadata, rather than sharing the raw file.

Raw decoders are complex code that reads untrusted offsets and lengths, and they get security fixes like any other parser. Keep raw software up to date, especially on servers that process uploaded files.