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Plenty of software that happily opens a Nikon NEF will not touch an .nrw, which is how a folder of Coolpix P7700 or P1000 files ends up stranded. Convertessa decodes them on your Mac and writes ordinary JPGs at the same pixel dimensions, with a quality level you choose for each run. Drop the folder in, get one JPG per NRW, and the raw files stay exactly as they were.
Nikon has two raw formats. NEF is the one everybody knows. NRW arrived with the Coolpix P6000 in 2008 and stayed on the enthusiast compacts — the P7000 through P7800, the Coolpix A, the P950 and P1000. Both are Nikon raw; they are not interchangeable, and software written against NEF regularly refuses an .nrw outright. That refusal is usually what sends someone looking for a converter in the first place.
What happens here is a full decode, not a shortcut. Every NRW carries a camera-rendered JPEG preview inside it, and pulling that out would be quick and lazy. Instead libvips and the raw decoder behind it demosaic the actual sensor mosaic and encode a JPG at the file's real pixel dimensions. The white balance the camera recorded is applied, the orientation flag is honoured, and the result is a neutral rendering.
Neutral is the operative word. These settings sit in the file as tags, and a general-purpose decoder does not act on any of them:
You shot with Monochrome selected, the rear screen showed black and white all day, and the converted files come back in colour. The sensor recorded colour and always did; the monochrome was a rendering instruction meant for the camera's own JPEG. The same mechanism explains noise: a 1/2.3-inch P1000 frame at ISO 800 looks grainier after a neutral decode than the JPEG the camera handed you, because that noise reduction was never part of the raw data. If the camera's rendering is what you actually wanted, shoot RAW+JPEG. Convert the NRW when you want to start from what the sensor saw.
Drag the folder of .nrw files onto the queue. A full card converts in one pass and each file reports as it finishes, so you can see straight away if a frame failed to decode.
Choose JPG, then set the quality for the run. Small-sensor Coolpix files hold less fine detail than a DSLR frame, so 85 to 90 usually looks identical to higher settings at half the size.
Convert a single NRW and open it before committing. If the neutral rendering looks flatter than the camera's own JPEG, that is expected — settle on your quality number, then send the rest through.
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No. Both are Nikon raw, but NRW came out of the Coolpix line and its internals differ enough that plenty of NEF-capable software rejects it. Renaming .nrw to .nef occasionally fools a viewer into opening the file, but it is a coin flip and it fixes nothing downstream — the bytes are unchanged. A real decode is the route that always works.
No. Every NRW contains a camera-rendered preview and extracting it would be fast, but that image is smaller than the full frame and carries the camera's own processing. Convertessa demosaics the sensor mosaic instead and encodes a JPG at the file's real pixel dimensions. That is exactly why the output looks neutral rather than punchy: it is the sensor data, not Nikon's rendering of it.
Because Monochrome was a Picture Control setting, and Picture Control is a tag telling the camera how to render its own JPEG. The raw data underneath is colour and always was. A general-purpose decoder reads the sensor data and ignores the instruction, so you get a colour image. Convert for the pixels, then desaturate in an editor if black and white is the goal.
The Coolpix applies noise reduction while building its own JPEG, and that processing never touches the raw file. A neutral decode of a 1/2.3-inch sensor at ISO 800 will therefore look grainier than the JPEG the camera gave you. Nothing has gone wrong — you are seeing the unfiltered capture. Run it through a denoiser afterwards, or shoot RAW+JPEG so you keep both renderings.
Yes. A run has one target format, not one source format, so a folder of mixed Nikon files all comes out as JPG:
convertessa ./Coolpix/ --to jpg -o ~/Exports --quality 88
The app's queue behaves the same way — drop the folder, choose one target, one pass.
The white balance the camera recorded is applied during the decode and baked into the JPG. After that it stops being a raw parameter — shifting it means editing 8-bit pixels, which is coarser and lossier than re-rendering the raw. If a frame has a white balance you know is wrong, correct it in a raw editor and convert that export instead of fighting the JPG.
For web and messaging, 80 to 85 is usually indistinguishable at screen size and roughly halves the file. If the JPG becomes your working copy, use 92 or higher, because every later save re-encodes it and the damage accumulates. The safest habit is to keep the .nrw and convert again at a different quality when you need one, rather than re-saving a JPG.