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denef - Decode NEF image files
$Id: README,v 1.2 2000/12/10 21:51:00 daniel Exp $
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This is a utility which decodes 'NEF' files - the raw image files from the
Nikon D1 camera, and produces an image which can be processed by standard
image processing tools.

This is a development release and simply represents a stake in the ground
from which further development will continue. Once compiled, usage is very
simple...

	denef	filename.nef

(Where, obviously, filename.nef is replaced by the NEF file you wish to
decode).

There are now a number of options, do 'denef --help' for a list, which allow
you to exchange interpolators, skip a couple of post-processing steps if
necessary, process only a part of the NEF file, change output filenames, etc.

The utility will produce one two files, their default names are:

	nef.ppm		The decoded NEF data
	histo.pgm	A simple histogram showing distribution of
			intensities. (This is now optional, default OFF)

What this utility currently DOES do...

     * Reads NEF file and extracts image data
     * Interpolates NEF data into linear RGB image
     * Color corrects to sRGB (or fairly close to)
	     [Since the R/G/B filters on the D1 aren't 1:1 with
	      any R/G/B I know of - Without color correction images
	      always seem washed out]	   
     * Gamma converts linear data to standard 'camera data' gamma curve
     * Outputs 24 bit PPM image data, with unidirectional floyd-steinberg
       dithering.
     * Allow only a subset of the image to be converted
     * Allow selection of an interpolation algorithm (The code is
       modularized properly, it just doesn't use it)

What this utility currently DOES NOT do (but in most cases will eventually
do).

     * Sharpen the image (So you'll have to do that yourself)
     * Filter the image for 'local anomalies' from the interpolation
       process.. [Interpolation can introduce some artifacts, which 
       in some cases can be filtered]
     * Attempt to adjust the levels of the resulting image based on the
       histogram.
     * Output JPEG/TIFF
     * Transfer the EXIF metadata from the NEF file to the output file
     * Allow multiple color-corrections
     * Allow the luminance data ONLY to be extracted
     * Allow the output of 48 bit (16 bit each of R,G,B) data (pre-gamma)
     * Provide support for batch-converting many files
     * Lots of other things.

My apologies if the code is badly commented or if there are lots of blocks
of code ifdef'ed or commented out since this IS development code and is a
little organic right now.. Please find it useful, but try not to expect any
level of 'support' just yet, it compiles fine on a RedHat 6.2 intel machine,
on other platforms, your mileage may vary.

Daniel Stephens - Dec 10 2000.