Create ex1.m

ex1.m

@@ -0,0 +1,113 @@
+close all;
+
+
+filename = 'titan';
+img = imread(strcat(filename,'.jpg'));
+[sx,sy,ch] = size(img);
+fac = 2;
+
+nn_img = resize_nn(sx,sy,fac,img);
+bilinear_img = resize_bilinear(sx,sy,fac,img);
+cubic_img  = resize_bicubic(sx,sy,fac,img);
+
+imwrite(nn_img, strcat(filename,'_nn.jpg'));
+imwrite(bilinear_img,strcat(filename,'_bilinear.jpg'));
+imwrite(cubic_img,strcat(filename,'_cubic.jpg'));
+
+function nn_img = resize_nn(sx,sy,fac,img)
+nn_img = uint8(zeros(size(img).* [fac,fac,1]));
+    for x = 1:sx
+        for y = 1:sy
+
+            nn_img(fac*x,fac*y-1,:) = img(x,y,:);
+
+            nn_img(fac*x-1,fac*y,:) = img(x,y,:);
+
+            nn_img(fac*x,fac*y,:) = img(x,y,:);
+
+            nn_img(fac*x-1,fac*y-1,:) = img(x,y,:);
+
+        end
+    end
+end
+
+
+function bilinear_img = resize_bilinear(sx,sy,fac,img)
+
+bilinear_img = uint8(zeros(size(img).* [fac,fac,1]));
+
+for i=1:sx
+    for j=1:sy
+      bilinear_img(1+(i-1)*fac,1+(j-1)*fac,:)=img(i,j,:); 
+    end
+end
+
+    for i=1:1+(sx-2)*fac     
+        for j=1:1+(sy-2)*fac 
+
+           if not(((rem(i-1,fac)==0) && (rem(j-1,fac)==0)) )
+               %calcula os 4 pixeis mais próximos para interpolação
+               inx = ceil(i/fac);
+               iny = ceil(j/fac);
+
+               interp00=double(bilinear_img( inx*fac-1,iny*fac-1,:)); 
+               interp10=double(bilinear_img( inx*fac+1,iny*fac-1,:));
+               interp01=double(bilinear_img( inx*fac-1,iny*fac+1,:));
+               interp11=double(bilinear_img( inx*fac+1,iny*fac+1,:));
+
+               x=rem(i-1,fac); %coordenadas do pixel interpolado
+               y=rem(j-1,fac);  
+
+               dx=x/fac; %
+               dy=y/fac;
+
+               c1=interp00;    %constantes da interpolação
+               c2=interp10-interp00;
+               c3=interp01-interp00;
+               c4=interp00-interp10-interp01+interp11;           
+               bilinear_img(i,j,:)=c1+c2*dx+c3*dy+c4*dx*dy; %pixel resultante
+            end
+        end
+    end
+end
+function cubic_img = resize_bicubic(sx,sy,fac,img)
+    cubic_img = uint8(zeros(size(img).* [fac,fac,1]));
+    for i=1:(sx*fac)-6    
+        for j=1:(sy*fac)-6
+           inx = ceil(i/fac);
+           iny = ceil(j/fac);
+           interp = double(zeros(4,4,3)); 
+           for polx = -1:2
+               for poly = -1:2
+                   interp(polx+2,poly+2,:) = double(img((inx+polx)+1,(iny+poly)+1,:));
+               end
+           end
+
+           for channel = 1:3
+               cubic_img(i,j,channel) = BicubicInterpolate(interp(:,:,channel),1,1);
+           end
+
+
+
+        end
+    end
+end
+
+function [output] = BicubicInterpolate(points, coefx, coefy)
+    x1 = CubicInterpolate( points(1,1), points(2,1), points(3,1), points(4,1), coefx );
+    x2 = CubicInterpolate( points(1,2), points(2,2), points(3,2), points(4,2), coefx );
+    x3 = CubicInterpolate( points(1,3), points(2,3), points(3,3), points(4,3), coefx );
+    x4 = CubicInterpolate( points(1,4), points(2,4), points(3,4), points(4,4), coefx );
+
+    output = CubicInterpolate( x1, x2, x3, x4, coefy );
+end
+
+
+function [output] = CubicInterpolate(v0, v1, v2, v3, coef )
+    A = (v3-v2)-(v0-v1);
+    B = (v0-v1)-A;
+    C = v2-v0;
+    D = v1;
+    output =  D + coef * (C + coef * (B + coef * A));
+end
+