/*         TP 5           */
                            
                            /* PARTIE 1 */ 
                            
                            clf()
                            U=double(imread('/Users/gghis/Desktop/A_aa_MT12_TP_Sci/Images/mandrill.bmp'));
                             scf(1)
                             imshow(mat2gray(U))
                            
                      
                      
                      
                      
                      
                      
                      
                      
                            V=U;
                            W=U;
                            
                            /* Q1  */
                            
                           V(1:50,1:50)=zeros(50,50)
                         
                          
                            clf()
                            scf(2)
                            subplot(2,2,1)
                            imshow(mat2gray(U))
                            subplot(2,2,2)
                            imshow(mat2gray(V))
                             
                               
                            W(1:50,1:50)=ones(50,50)*54.5;
                            scf(3)
                            imshow(mat2gray(W))
                            
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                          
                            /* Partie 2 : Bruiter une image */
                            /* Q 2 */ 
                            /* Q 2.(a)*/
                            
                            
                            function res=bruitgaus(U,sig)
                                Si=size(U)
                                m=Si(1)
                                n=Si(2)
                                res=U +  grand(m, n, "nor", 0, sig); 
                            endfunction
                            
                             sig=100
                            Ub=bruitgaus(U,sig);
                             scf(4)
                             imshow(mat2gray(Ub))
                            
                            /* Q 2.(b)*/
                            function Uimp=bruit_imp(U,p)
                                [N,M]=size(U)
                                 L=rand(N,M)
                                I=rand(N,M);
                                Uimp = 255*L.*(I<p/100)+(I>=p/100).*U;
                            endfunction
                            
                            
                            p=20
                             Uimp=bruit_imp(U,p) ;
                             scf(5)
                              imshow(mat2gray(Uimp))
                             
                             /* Partie 3 : `filtre moyenne et médian" */
                             
                             /* Q 3  */
                             //f=10; 
                             // f=80;
                              f=160; 
                            [N,M]=size(U);
                            Ubig=zeros(N+(2*f),M+(2*f)); 
                            Ubig(f+1:N+f,f+1:M+f)=U;
                             
                              scf(6)
                             imshow(mat2gray(Ubig))
                            
                            
                             /* Q4 */ 
                             
                             /* Q4  (a)  Moyenne des voisins */
                             function res=moyenne(U,f)
                                [N,M]=size(U);
                                Ubig=zeros(N+2*f,M+2*f); 
                                Ubig(f+1:N+f,f+1:M+f)=U;
                                Utemp=zeros(N+2*f,M+2*f);
                                for i=f+1:N+f 
                                    for j=f+1:M+f 
                                       Utemp(i,j)= mean(Ubig(i-f:i+f,j-f:j+f));
                                    end 
                                end
                                res=Utemp(f+1:f+N,f+1:f+M)
                            endfunction
                            
                            
                            //f=10, 30  pas terrible 
                             f=2
                             
                            sig=30
                            Ub=bruitgaus(U,sig);
                            Ub_DeBruit_Moy=moyenne(Ub,f);
                            
                             scf(7)
                             subplot(1,3,1)
                             imshow(mat2gray(U))
                             title('Image originale')
                             subplot(1,3,2)
                             imshow(mat2gray(Ub))
                             title('Image bruitée')
                             subplot(1,3,3)
                             imshow(mat2gray(Ub_DeBruit_Moy))
                             title('Image débruitée')
                            
                            
                             /* Q4  (b)   Mediane des voisins  */
                             
                             
                            function res=mediane(U,f)
                                [N,M]=size(U);
                                Ubig=zeros(N+2*f,M+2*f); 
                                Ubig(f+1:N+f,f+1:M+f)=U;
                                Utemp=zeros(N+2*f,M+2*f);
                                for i=f+1:N+f 
                                    for j=f+1:M+f 
                                       Utemp(i,j)= median(Ubig(i-f:i+f,j-f:j+f));
                                      end 
                                end
                                res=Utemp(f+1:f+N,f+1:f+M);
                            endfunction
                            
                            Uimp=bruit_imp(U,30);
                             Uimp_debruite_median=mediane(U,2);
                             
                             
                               scf(8)
                              subplot(1,3,1)
                              imshow(mat2gray(U))
                              title('Image originale')
                              subplot(1,3,2)
                             imshow(mat2gray(Uimp))
                             title('Image bruitée p')
                             subplot(1,3,3)
                             imshow(mat2gray(Uimp_debruite_median))
                             title('Image débruitée mediane')
                             
                             
                             
                            /* Partie 4 : détecter les contours */
                             
                             
                             /* Q 5  */
                            function res=contour(U,f)
                                 [N,M]=size(U);
                                 Ubig=zeros(N+2*f,M+2*f); 
                                Ubig(f+1:N+f,f+1:M+f)=U;
                                Utemp=zeros(N+2*f,M+2*f);
                                for i=f+1:N+f 
                                    for j=f+1:M+f 
                                       Utemp(i,j)= sqrt((Ubig(i+1,j)-Ubig(i-1,j))^2+(Ubig(i,j+1)-Ubig(i,j-1))^2)/2;
                                      end 
                                end
                                res=Utemp(f+1:f+N,f+1:f+M);
                            endfunction
                            
                            
                             U_cont=contour(U,1);
                             
                            scf()
                             subplot(1,2,1)
                            imshow(mat2gray(U))
                            title('Image originale')
                            subplot(1,2,2)
                            imshow(mat2gray(U_cont))
                            title('Image contour')