The "Art" of NEF Conversion

by Uwe Steinmueller (last updated 10/06/2000)

NEF Conversion Forum

NEF Test File

If you click on the photo you can download this photo in NEF format. I (Uwe Steinmueller) keep all copyright on this picture but also grant to everyone to play with it and get used to NEF conversion processI think the photo is technically quite ok to get you a fist NEF experience.

Why NEF files?

With the popular professional SLR "Nikon D1" Nikon introduced a proprietary RAW file format NEF (Nikon Electronic Image Format) with about 4MB filesize.

Why did Nikon not stick to standards like JPG or TIF?

• JPG is a lossy format with the only purpose to save space while to lose as little as possible image quality relative to the compression ratio. If space and speed would not be in issue JPGs would not exist. But space and speed are very important factors in real life computing (the D1 is quite a powerful computer) and that is why JPG are so important.

• TIF produce large files. The D1 creates images with 2000x1312 pixels and has a potential color depth of 12bit. As TIF only supports 8 or 16 bit this would get one 16 bit TIF file to 15MB of file size. Here the write speed of D1/CF cards and the capacity of todays CF cards or even Microdrives set the limit

That is why Nikon decided to have either JPGs (FINE mode needs about 1.1 MB of size) or RAW files which are just a "dump" of the CCD content. The concept of RAW files is not new for digital cameras (used by the Kodak professional line) and is also used by scanning software like Silverfast (you capture a raw scan and the software decodes and interpretes it later). The NEF files should contain all image content captured by the CCD and thus get you theortically to the optimal possible results for the D1.

Here is a description of NEFs and TIFs for the D1 by Richard Parkinson

"..., the TIFF is bigger so it has more information, right? No! The NEF format is propriatory and is, in effect, a raw dump of the CDD information, it has 12 bits of data per pixel. So (12 * 2008 * 1320)/8 = 3,975,840 bytes of data in the image. Now a NEF also has a crude thumbnail and some extra info, so the file size is actually 4,063,232 bytes. The TIFF format stores the data in a different way, the one that comes from the D1 is an 8 bit TIFF, that means that each pixel contains 8 bits (1 byte) for each color (Red, Green and Blue), this gives 3 * 2000 * 1320 = 7,920,000 bytes for the image. Again some extra info is stored with the TIFF so they end up at 7,938,048 bytes. Now comes the complex part, the 12 bits used in the NEF is actually more information than the 24 bits stored in the TIFF because of the way the CCD works, basically each pixel in the D1 only gives 1 color, the others are interpreted from the pixels of those colors nearby.

So the NEF which is smaller contains more information, but in addition to that it has had less processing, so it gives you more scope for improvement later to correct any problems of color balance, exposure etc. Think of it this way, if you want the maximum detail do you keep the original or a copy? Obviously the down side of the NEF is that you need a program to read it, fortunatally for us users the likes of Mike (QImage) and Eric (Bibble) have alowed us to use this format without the need for the expensive and clumsy Nikon Capture.

At the end of the day you have to decide:
TIFF = big, good qualility, standard format JPEG = Small, lossy compression, standard format NEF = Medium Size, best quality potential, propriatory format

You pays your money and takes your choice, but in my book the NEF wins hands down! Only use JPEG if you are short on storage or you need the speed of storage for rapid shots, I never use TIFF."

Here is Daniel Stephens "Decoding NEF" article.

The buyers of the D1 (myself included) were not too happy that when they buy the D1 they can capture NEF files but NIKON only provides the software to decode for additional $500. Most people see this as a hidden price tag (Kodak includes the software with the camera to decode its RAW files).

Because of this price tag for the software some shareware authors managed to write software which can decode these NEF files. That is why D1 users have the choice among three different software packages.

I believe one needs all three programs (on the Mac only NC and MacBibble) as there is not one best solution. On the downside I find more and more that the optimal solution is somewhere in the middle (nowhere) of all these programs. Here is a feature list of the available programs (I use all three and all findings are bases on my own experience)

NEF Converter Feature Chart

Uwe's Nikon Capture Defect List

Glossery