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I have a recently superseded Nikon D70 on order and have begun thinking about a workflow for handling raw images on the Mac. Another useful feature of Tiger (I've not seen it documented, or noticed it in Panther) is support for NEF right in the Finder itself. Furthermore, Preview can open and display the full-sized image.

What is raw?

I've read that raw can be thought of as a kind of "digital negative". According to Wikipedia:

A camera raw image file contains the unprocessed data from the image sensor of a digital camera. Also called raw (although it is not an acronym) or CCD-raw (even for CMOS sensors), its format is proprietary and differs from one manufacturer to another, and sometimes between cameras made by one manufacturer. The image must be processed and converted to an RGB format such as TIFF or JPEG before it can be manipulated by a bitmap graphics editor, printed, or displayed by a typical web browser.

Adobe is promoting the Digital Negative (.dng) as a universal archival format for raw images.

What is NEF?

NEF is an acronym for Nikon Electronic Format, Nikon's own version of raw with 12-bit lossless (see below) compression. As Nikon explain in a Nikon Capture-focussed press release:

A NEF file from a Nikon digital SLR camera consists of three key components that include raw image data captured by the imaging sensor, thumbnail images of the raw data, and a unique instruction set that retains camera settings from the moment a picture was taken.

During postproduction in Capture 4.0 software, these original camera settings can be tweaked, edited and saved as a variation of the instruction set, thereby leaving the original raw data unaffected, yet achieving the effects of the editing on the final image. Only Nikon's Capture software completely integrates all of the information saved within the instruction set of a NEF file, thus avoiding loss of valuable camera-settings instructions and overall control of the image.

When shooting in NEF mode, all Nikon digital SLR models... capture 12-bit images, instead of 8-bit in JPEG and TIFF modes. In Capture 4.0 software, these 12-bit images are processed into full 16-bit images using advanced algorithms, offering tone and color enhancements with the smoothest gradation and fidelity. Using Capture 4.0, a 16-bit NEF image can be easily transformed into a JPEG or TIFF.

Is NEF really lossless?

Nikon say so, but this article may convince you otherwise. Does it matter? Probably not as there's only so much that the human eye can distinguish, as per Galbraith's assertion that NEF is "visually lossless but numerically lossy". This makes the discussion somewhat academic—or ethical if you want to argue the toss over Nikon's not entirely accurate claim...

Do I need to buy extra software?

I download a sample NEF-format image (from a D70) here and was very surprised to see it preview in the Mac OS X 10.4 Finder:

The Preview application was able to open the full-sized 5MB raw image and display EXIF metadata. Interestingly, the Finder and Preview are both .dng-aware too.

iPhoto 5.0.2 (not included with Tiger; part of the iLife suite) is able to import and display NEF images (but .dng causes it to stop responding); you can also set up a Smart Album to automatically find such images:

Viewing NEF images is one thing; manipulating them is another. You do need a raw converter but not necessarily Nikon Capture; there are several to choose from. If you have Adobe Photoshop Elements 3.0 (or Photoshop CS2) you can download a Camera raw plug-in (ACR) with up-to-date support for current cameras. You can also download the open-source dcraw for Mac OS X here; it's code is apparently used by Adobe, and was recently updated to crack Nikon's encrypted (why?) white balance data.

Help for Photoshop Elements 3.0 offers a useful rundown of the options on import: search for "camera raw image options". There's also a brief video introduction here.

BTW, PhotoToolCM, a great contextual menu for viewing and copying EXIF data, is compatible with Mac OS X 10.4 but not with NEF images (as of v2).

Update 01.06.05: Microsoft have announced that it plans to support raw in Windows XP and its replacement, Longhorn. The announcement does not correspond to the availability of any actual products.

Update 11.07.05: Erland Flaten wrote (see comment) saying that the Finder and Preview seem to be unaware of NEF images from the D50. He e-mailed me one and sure enough, neither the Finder, Preview, or iPhoto 05 can display NEF files from the D50. As D50 originated NEFs open fine with ACR 3.4 in Photoshop CS2 we can assume Apple's software is lacking the ability to acknowledge the D50.

Update 02.11.05: Mac OS X 10.4.3 updates raw file support.

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