--- a
+++ b/Image Segmentation/region growing/regiongrowing.m
@@ -0,0 +1,90 @@
+function J=regiongrowing(I,x,y,reg_maxdist)
+% This function performs "region growing" in an image from a specified
+% seedpoint (x,y)
+%
+% J = regiongrowing(I,x,y,t) 
+% 
+% I : input image 
+% J : logical output image of region
+% x,y : the position of the seedpoint (if not given uses function getpts)
+% t : maximum intensity distance (defaults to 0.2)
+%
+% The region is iteratively grown by comparing all unallocated neighbouring pixels to the region. 
+% The difference between a pixel's intensity value and the region's mean, 
+% is used as a measure of similarity. The pixel with the smallest difference 
+% measured this way is allocated to the respective region. 
+% This process stops when the intensity difference between region mean and
+% new pixel become larger than a certain treshold (t)
+%
+% Example:
+%
+% I = im2double(imread('medtest.png'));
+% x=198; y=359;
+% J = regiongrowing(I,x,y,0.2); 
+% figure, imshow(I+J);
+%
+% Author: D. Kroon, University of Twente
+
+%Check to see if they provided a max distance away from the mean to stop
+%algorithm
+if(exist('reg_maxdist','var')==0), reg_maxdist=0.2; end
+if(exist('y','var')==0), figure, imshow(I,[]); [y,x]=getpts; y=round(y(1)); x=round(x(1)); end
+
+J = zeros(size(I)); % Output 
+Isizes = size(I); % Dimensions of input image
+
+reg_mean = I(x,y); % The mean of the segmented region
+reg_size = 1; % Number of pixels in region
+
+% Free memory to store neighbours of the (segmented) region
+neg_free = 10000; neg_pos=0;
+neg_list = zeros(neg_free,3); 
+
+pixdist=0; % Distance of the region newest pixel to the region mean
+
+% Neighbor locations (footprint)
+neigb=[-1 0; 1 0; 0 -1;0 1];
+
+% Start region growing until distance between region and posible new pixels become
+% higher than a certain treshold
+while(pixdist<reg_maxdist&&reg_size<numel(I))
+
+    % Add new neighbors pixels
+    for j=1:4,
+        % Calculate the neighbour coordinate
+        xn = x +neigb(j,1); yn = y +neigb(j,2);
+        
+        % Check if neighbour is inside or outside the image
+        ins=(xn>=1)&&(yn>=1)&&(xn<=Isizes(1))&&(yn<=Isizes(2));
+        
+        % Add neighbor if inside and not already part of the segmented area
+        if(ins&&(J(xn,yn)==0)) 
+                neg_pos = neg_pos+1;
+                neg_list(neg_pos,:) = [xn yn I(xn,yn)]; J(xn,yn)=1;
+        end
+    end
+
+    % Add a new block of free memory
+    if(neg_pos+10>neg_free), neg_free=neg_free+10000; neg_list((neg_pos+1):neg_free,:)=0; end
+    
+    % Add pixel with intensity nearest to the mean of the region, to the region
+    dist = abs(neg_list(1:neg_pos,3)-reg_mean);
+    [pixdist, index] = min(dist);
+    J(x,y)=2; reg_size=reg_size+1;
+    
+    % Calculate the new mean of the region
+    reg_mean= (reg_mean*reg_size + neg_list(index,3))/(reg_size+1);
+    
+    % Save the x and y coordinates of the pixel (for the neighbour add proccess)
+    x = neg_list(index,1); y = neg_list(index,2);
+    
+    % Remove the pixel from the neighbour (check) list
+    neg_list(index,:)=neg_list(neg_pos,:); neg_pos=neg_pos-1;
+end
+
+% Return the segmented area as logical matrix
+J=J>1;
+
+
+
+