PNGNQ - PNG NEUQUANT
VERSION 0.41

USAGE: 

  pngnq [-vfhV][-s sample factor][-n colours][input files]
  options:
     -v Verbose mode. Prints status messages.
     -f Force ovewriting of files.
     -s Sample factor. The neuquant algorithm samples pixels stepping by this
value.
     -n Number of colours the quantized image is to contain. Range: 2 to 256.
Defaults to 256.
     input files: The png files to be processed. Defaults to standard input if
not specified.

     -V Print version number and library versions.
     -h Print this help.

  Quantizes a 32-bit RGBA PNG image to an 8 bit RGBA palette PNG
  using the neuquant algorithm. The output file name is the input file name
  extended with "-nq8.png"


NOTES:

Pngnq is a tool for quantizing PNG images in RGBA format.
Pngnq is an adaptation by Stuart Coyle of Greg Roelf's pnqquant program
using Anthony Dekker's neuquant algorithm.

Pngnq exists because I needed a lot of png images in RGBA format
to be quantized. After some searching, the only tool I could find
that worked was pngquant. I tried pngquant but found that the median
cut algorithm that it uses, with or without dithering, gave inferior
looking results to the neuquant algorithm. You can see the difference
demonstrated on the neuquant web page:  
http://members.ozemail.com.au/~dekker/NEUQUANT.HTML.

The program was written to fulfill the specific needs of the small
project I was working on, and as such does not have all the
functionality one could want. 

I use Greg Roelf's png reading and writing code unchanged for the most part.
The pngnq source code includes neuquant32, which is an extension of Anthony
Dekker's 
neuquant, to make it handle 4 channels of pixel data.

Specifically the things that it lacks are:

	I want to change the error measure to use CIE u' v' color
	space and see if results are visually better.

	No dithering. 

	Limited image input formats. I am not doing much checking on
	the image pixel depth etc.

	This has not been tested on platforms other than GNU/Linux on x86 and AMD64, 
        BSD on x86 and Mac OSX 10.4 on Intel. 


Copyright (c) Stuart Coyle 2004-2006

See LICENCES for details of copyrights held on this program.


PNGCOMP - PNG COMPARISON
VERSION 0.1

USAGE: 
  pngcomp [-vVh] image1.png image2.png

  options: v - verbose, does nothing as yet.
           V - version, prints version information.
           h - help, prionts this message.

  inputs: image1.png and image2.png are the two images that are to be compared.
          it is required that they be the same size.

  This program give some basic statistics about the difference between two
images.
  It was created as a measure of various color quantization methods.


NOTES:
The stats created by this program are purely based on the Euclidean distance 
in RGBA space between the pixels of the images. Later versions will include 
different measures such as CIE color space measurements and filters for 
perception models.

The error calculation used reflects the percieved quality of images only
roughly. 
To determine what image is better nothing can surpass having a look for
yourself! 

Copyright (c) Stuart Coyle 2004-2006

See LICENCES for details of copyrights held on this program.

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 1067    2439  43.7% -lh5- 8b62 Jun 16 23:24 png_neuquant/LICENSE
[generic]                77009  167120  46.1% -lh5- b753 Jun 20 02:45 png_neuquant/pngcomp
[generic]                80501  175680  45.8% -lh5- 71fa Jun 20 02:45 png_neuquant/pngnq
[generic]                 1683    3457  48.7% -lh5- cb7c Jun 20 03:00 png_neuquant/png_neuquant-mos.readme
[generic]                 1166    2220  52.5% -lh5- 9f75 Jun 17 05:09 png_neuquant/README
[generic]                  596    1060  56.2% -lh5- 3090 Jun 16 23:24 png_neuquant/README.pngcomp
[generic]                  276     545  50.6% -lh5- 9535 Jun 16 23:24 png_neuquant/sources/Makefile
[generic]                 3950   11557  34.2% -lh5- 682c Jun 16 23:25 png_neuquant/sources/neuquant32.c
[generic]                 1446    3285  44.0% -lh5- 44ad Jun 16 23:24 png_neuquant/sources/neuquant32.h
[generic]                 2315    7058  32.8% -lh5- c0a3 Jun 16 23:24 png_neuquant/sources/pngcomp.c
[generic]                 4600   13293  34.6% -lh5- 9840 Jun 16 23:24 png_neuquant/sources/pngnq.c
[generic]                 5177   18454  28.1% -lh5- 8629 Jun 16 23:24 png_neuquant/sources/rwpng.c
[generic]                 1158    3059  37.9% -lh5- b420 Jun 16 23:24 png_neuquant/sources/rwpng.h
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        13 files  180944  409227  44.2%            Jun 20 13:46