--- a
+++ b/util/im2col_mean_removal.m
@@ -0,0 +1,27 @@
+function im = im2col_mean_removal(varargin)
+% 
+
+NumInput = length(varargin);
+InImg = varargin{1};
+patchsize12 = varargin{2}; 
+
+z = size(InImg,3);
+im = cell(z,1);
+if NumInput == 2
+    for i = 1:z
+        iim = im2colstep(InImg(:,:,i),patchsize12);
+        im{i} = bsxfun(@minus, iim, mean(iim))'; 
+%         iim = bsxfun(@minus, iim, mean(iim)); 
+%         im{i} = bsxfun(@minus, iim, mean(iim,2))';
+    end
+else
+    for i = 1:z
+        iim = im2colstep(InImg(:,:,i),patchsize12,varargin{3});
+        im{i} = bsxfun(@minus, iim, mean(iim))'; 
+%         iim = bsxfun(@minus, iim, mean(iim)); 
+%         im{i} = bsxfun(@minus, iim, mean(iim,2))';
+    end 
+end
+im = [im{:}]';
+    
+    
\ No newline at end of file