Extract Skin pixels in face using scale space filtering method <p>I'm trying to implement color constancy method in this paper.'<a href="http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&amp;arnumber=6701394" rel="nofollow">http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&amp;arnumber=6701394</a>'. In this paper , the skin pixels are detected using scale space filtering method. I'm unable to go forward after forming a scale space image for the histogram of skin pixels extracted from face regions. please help me out. thanks in advance.</p> <pre><code>close all; clear all; clc; a = imread('Input.jpg'); %subplot(2,2,1); imshow(a); [row col dim] = size(a); hsv = rgb2hsv(a); % convert rgb to hsv h = hsv(:,:,1); h=h(:); s = hsv(:,:,2); v = hsv(:,:,3); [Hi,x]=hist(h,200); % forming an histogram with 200 bins plot(x,Hi); N=sum(Hi); Hist=Hi./N; % Normalize the histogram P=[]; figure;plot(Hist); sigma=2:2:50; % range of sigma values taken for forming scale space count=length(sigma); for i=1:count f1 = normpdf(-20:20,0,sigma(i)); % &lt;== f(x) gaussian distribution p1 = conv(Hist,f1,'same'); P=[P; p1]; subplot(count,1,i); plot(p1);%title('smoothed signal with sigma='num2str(sigma)); end % Here P is tha scale space image mask=[1 -2 1]; for j=1:count P_derv(j,:)=conv(P(j,:),mask,'same'); %figure; subplot(count,1,j); end %P_derv is the 2nd derivative of the scale space image. </code></pre> <p>Now , I have to found the zero contour and interval tree to identify the peak in histogram. The scale space filtering method is found in this paper. <a href="http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&amp;arnumber=1172729" rel="nofollow">http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&amp;arnumber=1172729</a></p>