commit : sureshrink init

denoise/denoise.c

@@ -41,6 +41,23 @@ double mad(double *x, int N) {
 	return sigma;
 }
 
+int minindex(double *arr, int N) {
+	double min;
+	int index,i;
+
+	min = DBL_MAX;
+	index = 0;
+	for(i = 0; i < N;++i) {
+		if (arr[i] < min) {
+			min = arr[i];
+			index = i;
+		}
+	}
+
+	return index;
+
+}
+
 void getDWTAppx(wt_object wt, double *appx,int N) {
 	/*
 	Wavelet decomposition is stored as
@@ -89,6 +106,7 @@ void visushrink(double *signal,int N,char *wname,char *method,char *ext,char *th
 	double sigma,td,tmp;
 	wave_object wave;
 	wt_object wt;
+	double *dout;
 
 	wave = wave_init(wname);
 	
@@ -110,11 +128,17 @@ void visushrink(double *signal,int N,char *wname,char *method,char *ext,char *th
 	iter = wt->length[0];
 	dlen = wt->length[J];
 
+	dout = (double*)malloc(sizeof(double) * dlen);
+
 	for (i = 1; i < J; ++i) {
 		iter += wt->length[i];
 	}
 
-	sigma = mad(wt->output+iter,dlen);
+	for(i = 0; i < dlen;++i) {
+		dout[i] = wt->output[iter+i];
+	}
+
+	sigma = mad(dout,dlen);
 	dwt_len = wt->outlength;
 
 	td = sqrt(2.0 * log(dwt_len)) * sigma / 0.6745;
@@ -139,6 +163,107 @@ void visushrink(double *signal,int N,char *wname,char *method,char *ext,char *th
 
 	idwt(wt,denoised);
 
+	free(dout);
+	wave_free(wave);
+	wt_free(wt);
+}
+
+void sureshrink(double *signal,int N,char *wname,char *method,char *ext,char *thresh,double *denoised) {
+	int J, filt_len,i,it,len,dlen,dwt_len,min_index,sgn;
+	double sigma,norm,td,tv,te,ct,thr,temp,x_sum;
+	wave_object wave;
+	wt_object wt;
+	double *dout,*risk;
+
+	wave = wave_init(wname);
+
+	filt_len = wave->filtlength;
+
+	J = (int) (log((double)N / ((double)filt_len - 1.0)) / log(2.0));
+
+	if (J > 50) {
+		J = 50;
+	}
+
+	wt = wt_init(wave,method,N,J);
+	setDWTExtension(wt,ext);
+
+	dwt(wt,signal);
+
+	len = wt->length[0];
+	dlen = wt->length[J];
+
+	dout = (double*)malloc(sizeof(double) * dlen);
+	risk = (double*)malloc(sizeof(double) * dlen);
+
+	for(it = 0; it < J;++it) {
+		dwt_len = wt->length[it+1];
+
+		for(i = 0; i < dlen;++i) {
+			dout[i] = wt->output[len+i];
+		}
+
+		sigma = mad(dout,dwt_len);
+
+		if ( sigma < 0.00000001) {
+			td = 0;
+		} else {
+			tv = sqrt(2.0 * log(dwt_len));
+			norm = 0.0;
+			for(i = 0; i < dwt_len;++i) {
+				norm += (wt->output[len+i] *wt->output[len+i]);
+			}
+			te =(norm - (double) dwt_len)/(double) dwt_len;
+			ct = pow(log((double) dwt_len)/log(2.0),1.5)/sqrt((double) dwt_len);
+
+			if (te < ct) {
+				td = tv;
+			} else {
+				x_sum = 0.0;
+				for(i = 0; i < dwt_len;++i) {
+					dout[i] = (dout[i]*dout[i]);
+					x_sum += dout[i];
+				}
+
+				for(i = 0;i < dwt_len;++i) {
+					risk[i] = ((double)dwt_len + 1 - 2 * ((double)i + 1) +x_sum +
+							dout[i]*((double)dwt_len - 1 -(double) i))/(double)dwt_len;
+				}
+
+				min_index = minindex(risk,dwt_len);
+				thr = sqrt(dout[min_index]);
+
+				td = thr < tv ? thr : tv;
+			}
+		}
+
+		td = td * sigma / 0.6745;
+
+		if(!strcmp(thresh,"hard")) {
+			for(i = 0; i < dwt_len;++i) {
+				if (fabs(wt->output[len+i]) < td) {
+					wt->output[i] = 0;
+				}
+			}
+		} else if(!strcmp(thresh,"soft")) {
+			for(i = 0; i < dwt_len;++i) {
+					if (fabs(wt->output[len + i]) < td) {
+						wt->output[i] = 0;
+					} else {
+						sgn = wt->output[len+i] >= 0 ? 1 : -1;
+						temp = sgn * (fabs(wt->output[len+i]) - td);
+						wt->output[i] = temp;
+					}
+				}
+		}
+
+		len += wt->length[it+1];
+	}
+
+	idwt(wt,denoised);
+
+	free(dout);
+	free(risk);
 	wave_free(wave);
 	wt_free(wt);
 }

denoise/denoise.h

@@ -7,6 +7,7 @@ Copyright (c) 2017, Rafat Hussain
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <float.h>
 #include <math.h>
 #include "../header/wavelib.h"
 
@@ -17,6 +18,8 @@ extern "C" {
 
 void visushrink(double *signal,int N,char *wname,char *method,char *ext,char *thresh,double *denoised);
 
+void sureshrink(double *signal,int N,char *wname,char *method,char *ext,char *thresh,double *denoised);
+
 double mad(double *x, int N);