This post is not likely of interest to regular readers of my blog (“Hi Mom”); I'm putting it here mostly for the search engines.
A Nikon D200 dSLR has two color-space settings: sRGB and Adobe RGB. People often ask which should be selected when shooting in raw mode, with the oft-provided answer that “it doesn't matter” because raw data has its own camera-specific raw-sensor-data color space, and sRGB vs. AdobeRGB comes in to play only when converting the raw sensor data to a different image format (e.g. JPEG).
Indeed, the color-space setting doesn't matter for the main picture, which is what people are generally asking about, so “it doesn't matter” is a good first approximation of the answer.
However, even when shooting raw, there are effects to the resulting NEF file from the on-camera color-space setting, so I thought I'd document them here for completeness:
The MakerNotes:ColorSpace metadata reflects the setting (“sRGB” vs. “Adobe RGB”).
The setting determines the color space for two JPEG images embedded within the NEF. The embedded JPEG images have no metadata of their own, so the only indication of their color space is the NEF's MakerNotes:ColorSpace metadata.
The setting determines the name of the NEF file: with sRGB, it's of the pattern “DSC_0001.NEF”, and with Adobe RGB, it's of the pattern “_DSC0001.NEF” (see D200 manual, English version, page 29).
Perhaps surprisingly, a NEF (at least a D200-produced NEF) contains two embedded JPEG images:
A small (570 × 375) “preview image”
A full-frame (3,872 × 2,592) “JPEG from raw” image, which is identical to the image inside a Large-size Basic-quality JPEG produced with the camera's JPEG Compression set to “Size Priority” (manual page 30).
Together, the two embedded JPGs add about 9-10% to the size of a compressed NEF.
It's interesting to note that if you shoot both raw and JPEG at the same time, you end up with six versions of the same picture, in two files:
- Raw full-frame sensor data in .NEF file
- Small (570 × 375) “preview image” JPEG embedded in the .NEF file
- Full-frame basic-quality size-priority-compression “JPEG from raw” embedded in the .NEF file
- Main JPEG image in the .JPG file whose size depends on the Image Size setting (manual page 32)
- Tiny (120 × 160) JPEG thumbnail embedded in the .JPG file
- Small (570 × 375) “preview image” embedded in the .JPG file
Images 3 and 4 are identical if the camera is set to produce Large Basic-quality size-priority JPEGs. The resulting .JPG file has a lot of metadata that the embedded “JPEG from raw” doesn't have, of course.
If you have Phil Harvey's most excellent ExifTool (now available in a Windows stand-alone executable), you can easily extract these embedded images:
exiftool -b -PreviewImage file.NEF > file-Preview.jpg exiftool -b -JpgFromRaw file.NEF > file-FromRaw.jpg exiftool -b -PreviewImage file.JPG > file-Preview.jpg exiftool -b -ThumbnailImage file.JPG > file-Thumb.jpg
Again, be warned that none of these extracted images have any metadata, including an indication of their color space.