/* * Otsu Thresholding algorithm * * Copyright (c) 2003 by Christopher Mei (christopher.mei@sophia.inria.fr) * * This plugin is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2  * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this plugin; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */import java.util.*;import ij.*;import ij.process.*;/**  *  This class implements a class of pixels with basic statistical functions. **/public class GrayLevelClass {    private static float[] probabilityHistogram;    public static boolean probabilityHistogramDone;    public static int N;    private int index;    private float omega;    private float mu;    public GrayLevelClass(ByteProcessor img, boolean first) {	if(!probabilityHistogramDone) {	    int[] histogram = img.getHistogram();	    probabilityHistogram = new float[256];	    	    for(int i=0; i<256 ; i++) {		probabilityHistogram[i] = ((float) histogram[i])/((float) N);		//IJ.write(" "+probabilityHistogram[i]);	    }	    probabilityHistogramDone = true;	}	if(first) {	    index = 1;	    omega = probabilityHistogram[index-1];	    if(omega == 0)		mu = 0;	    else		mu =  1*probabilityHistogram[index-1]/omega;	}	else {	    index = 2;	    omega = 0;	    mu = 0;	    for(int i=index; i<256 ; i++) {		omega +=  probabilityHistogram[i-1];		mu +=  probabilityHistogram[i-1]*i;	    }	    if(omega == 0)		mu = 0;	    else		mu /= omega;	}    }    public void removeFromBeginning() {	index++;	mu = 0;	omega = 0;	for(int i=index; i<256 ; i++) {	    omega +=  probabilityHistogram[i-1];	    mu +=  i*probabilityHistogram[i-1];//i*	}	if(omega == 0)	    mu = 0;	else	    mu /= omega;	/*mu *= omega;	  mu -= probabilityHistogram[index-2];//(index-1)*	  omega -= probabilityHistogram[index-2];	  if(omega == 0)	  mu = 0;	  else	  mu /= omega;*/    }    public void addToEnd() {	index++;	mu = 0;	omega = 0;	for(int i=1; i<index ; i++) {	    omega +=  probabilityHistogram[i-1];	    mu +=  i*probabilityHistogram[i-1];	}	if(omega == 0)	    mu = 0;	else	    mu /= omega;	/*mu *= omega;	  omega += probabilityHistogram[index-1];	  mu += probabilityHistogram[index-1];//index*	  if(omega == 0)	  mu = 0;	  else	  mu /=omega;	*/    }    public String toString() {	StringBuffer ret = new StringBuffer();		ret.append("Index : "+index+"\n");	ret.append("Mu : "+mu+"\n");	ret.append("Omega : "+omega+"\n");	/*for(int i=0; i<10; i++) {	    ret.append( "\n" );	    }*/		return ret.toString();    }    public float getMu() {	return mu;    }    public float getOmega() {	return omega;    }    public int getThreshold() {	return index;    }}