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src/Source/FreeImage/NNQuantizer.cpp  view on Meta::CPAN

// in "Network: Computation in Neural Systems" Vol. 5 (1994) pp 351-367.
// for a discussion of the algorithm.
//
// Any party obtaining a copy of these files from the author, directly or
// indirectly, is granted, free of charge, a full and unrestricted irrevocable,
// world-wide, paid up, royalty-free, nonexclusive right and license to deal
// in this software and documentation files (the "Software"), including without
// limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons who receive
// copies from any such party to do so, with the only requirement being
// that this copyright notice remain intact.

///////////////////////////////////////////////////////////////////////
// History
// -------
// January 2001: Adaptation of the Neural-Net Quantization Algorithm
//               for the FreeImage 2 library
//               Author: Hervé Drolon (drolon@infonie.fr)
// March 2004:   Adaptation for the FreeImage 3 library (port to big endian processors)
//               Author: Hervé Drolon (drolon@infonie.fr)
// April 2004:   Algorithm rewritten as a C++ class. 
//               Fixed a bug in the algorithm with handling of 4-byte boundary alignment.
//               Author: Hervé Drolon (drolon@infonie.fr)
///////////////////////////////////////////////////////////////////////

#include "Quantizers.h"
#include "FreeImage.h"
#include "Utilities.h"


// Four primes near 500 - assume no image has a length so large
// that it is divisible by all four primes
// ==========================================================

#define prime1		499
#define prime2		491
#define prime3		487
#define prime4		503

// ----------------------------------------------------------------

NNQuantizer::NNQuantizer(int PaletteSize)
{
	netsize = PaletteSize;
	maxnetpos = netsize - 1;
	initrad = netsize < 8 ? 1 : (netsize >> 3);
	initradius = (initrad * radiusbias);

	network = NULL;

	network = (pixel *)malloc(netsize * sizeof(pixel));
	bias = (int *)malloc(netsize * sizeof(int));
	freq = (int *)malloc(netsize * sizeof(int));
	radpower = (int *)malloc(initrad * sizeof(int));

	if( !network || !bias || !freq || !radpower ) {
		if(network) free(network);
		if(bias) free(bias);
		if(freq) free(freq);
		if(radpower) free(radpower);
		throw FI_MSG_ERROR_MEMORY;
	}
}

NNQuantizer::~NNQuantizer()
{
	if(network) free(network);
	if(bias) free(bias);
	if(freq) free(freq);
	if(radpower) free(radpower);
}

///////////////////////////////////////////////////////////////////////////
// Initialise network in range (0,0,0) to (255,255,255) and set parameters
// -----------------------------------------------------------------------

void NNQuantizer::initnet() {
	int i, *p;

	for (i = 0; i < netsize; i++) {
		p = network[i];
		p[FI_RGBA_BLUE] = p[FI_RGBA_GREEN] = p[FI_RGBA_RED] = (i << (netbiasshift+8))/netsize;
		freq[i] = intbias/netsize;	/* 1/netsize */
		bias[i] = 0;
	}
}

///////////////////////////////////////////////////////////////////////////////////////	
// Unbias network to give byte values 0..255 and record position i to prepare for sort
// ------------------------------------------------------------------------------------

void NNQuantizer::unbiasnet() {
	int i, j, temp;

	for (i = 0; i < netsize; i++) {
		for (j = 0; j < 3; j++) {
			// OLD CODE: network[i][j] >>= netbiasshift; 
			// Fix based on bug report by Juergen Weigert jw@suse.de
			temp = (network[i][j] + (1 << (netbiasshift - 1))) >> netbiasshift;
			if (temp > 255) temp = 255;
			network[i][j] = temp;
		}
		network[i][3] = i;			// record colour no 
	}
}

//////////////////////////////////////////////////////////////////////////////////
// Insertion sort of network and building of netindex[0..255] (to do after unbias)
// -------------------------------------------------------------------------------

void NNQuantizer::inxbuild() {
	int i,j,smallpos,smallval;
	int *p,*q;
	int previouscol,startpos;

	previouscol = 0;
	startpos = 0;
	for (i = 0; i < netsize; i++) {
		p = network[i];
		smallpos = i;
		smallval = p[FI_RGBA_GREEN];			// index on g