--- a
+++ b/Thoracic Organs Segmentation code/Histogr.m
@@ -0,0 +1,19 @@
+function [Thres] = Histogr(Img);
+
+Totalnum = size(Img,1)*size(Img,2)*size(Img,3);
+Img=reshape(Img, [Totalnum,1]);
+[Num,binsValue]=hist(double(Img),100);
+
+DesireNum = round(0.9*Totalnum);
+
+Cum=zeros(length(Num),1);
+Cum(1)=Num(1);
+
+for i=2:length(Num)
+    Cum(i)=Cum(i-1)+Num(i);
+end
+
+i=find(Cum>=0.955*max(Cum));
+plot(binsValue,Cum)
+Thres=binsValue(i(1));
+