Studi Komparatif Teknik Pembesaran Citra: Bicubic dan B-Spline

Antarmuka GUI MATLAB ini dapat dipakai untuk laboratorium sinyal bagi mahasiswa dan untuk menunjang penelitian bagi para peneliti. Anda bisa memesannya pada form pemesanan di bawah ini.

KODE UNTUK SALAH SATU EVENT CALLBACK:

% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

g=getimage(handles.axes1);
citra_semula= getimage(handles.axes6);

% B-Spline I 2x
inputI = g;
[r,c] = size(g);
vert = 2; hor = 2;

rn = floor(hor*r);
cn = floor(vert*c);

im_zoom = zeros(rn,cn);
for i = 1:rn;
    x1 = cast(floor(i/hor),'uint32');
    x2 = cast(ceil(i/hor),'uint32');
    if x1 == 0
        x1 = 1;
    end
    x = rem(i/hor,1);
    for j = 1:cn;
        y1 = cast(floor(j/vert),'uint32');
        y2 = cast(ceil(j/vert),'uint32');
        if y1 == 0
            y1 = 1;
        end
        ctl = inputI(x1,y1);
        cbl = inputI(x2,y1);
        ctr = inputI(x1,y2);
        cbr = inputI(x2,y2);
        y = rem(j/vert,1);
        tr = (ctr*y)+(ctl*(1-y));
        br = (cbr*y)+(cbl*(1-y));
        im_zoom(i,j,:) = (br*x)+(tr*(1-x));
    end
end
image_zoom = cast(im_zoom,'uint8');

error = citra_semula - (image_zoom);
MSE2 = sum(sum(error .* error)) / (r * c);

set(handles.edit5, 'String', num2str(MSE2));


% Pembesaran Bicubic 2x
vert = 2; hor = 2;
inputI = g;
[r c] = size(inputI);
rn = floor(hor*r);
cn = floor(vert*c);
%s = zoom;
im_zoom = cast(zeros(rn,cn),'uint8');
im_pad = zeros(r+4,c+4);
im_pad(2:r+1,2:c+1) = inputI;
im_pad = cast(im_pad,'double');
for m = 1:rn
    x1 = ceil(m/hor); x2 = x1+1; x3 = x2+1;
    p = cast(x1,'uint16');
    if(hor>1)
       m1 = ceil(hor*(x1-1));
       m2 = ceil(hor*(x1));
       m3 = ceil(hor*(x2));
       m4 = ceil(hor*(x3));
    else
       m1 = (hor*(x1-1));
       m2 = (hor*(x1));
       m3 = (hor*(x2));
       m4 = (hor*(x3));
    end
    X = [ (m-m2)*(m-m3)*(m-m4)/((m1-m2)*(m1-m3)*(m1-m4)) ...
          (m-m1)*(m-m3)*(m-m4)/((m2-m1)*(m2-m3)*(m2-m4)) ...
          (m-m1)*(m-m2)*(m-m4)/((m3-m1)*(m3-m2)*(m3-m4)) ...
          (m-m1)*(m-m2)*(m-m3)/((m4-m1)*(m4-m2)*(m4-m3))];
    for n = 1:cn
        y1 = ceil(n/vert); y2 = y1+1; y3 = y2+1;
        if (vert>1)
           n1 = ceil(vert*(y1-1));
           n2 = ceil(vert*(y1));
           n3 = ceil(vert*(y2));
           n4 = ceil(vert*(y3));
        else
           n1 = (vert*(y1-1));
           n2 = (vert*(y1));
           n3 = (vert*(y2));
           n4 = (vert*(y3));
        end
        Y = [ (n-n2)*(n-n3)*(n-n4)/((n1-n2)*(n1-n3)*(n1-n4));...
              (n-n1)*(n-n3)*(n-n4)/((n2-n1)*(n2-n3)*(n2-n4));...
              (n-n1)*(n-n2)*(n-n4)/((n3-n1)*(n3-n2)*(n3-n4));...
              (n-n1)*(n-n2)*(n-n3)/((n4-n1)*(n4-n2)*(n4-n3))];
        q = cast(y1,'uint16');
        sample = im_pad(p:p+3,q:q+3,:);
        im_zoom(m,n,1) = X*sample(:,:,1)*Y;
    end
end
im_zoom = cast(im_zoom,'uint8');

error = citra_semula - (im_zoom);
MSE3 = sum(sum(error .* error)) / (r * c);

set(handles.edit9, 'String', num2str(MSE3));

% Pembesaran B-Spline II 2x

zoom = 2;
inputI = g;

[r c] = size(inputI);
img = cast(inputI,'double');
faktor = 1/zoom;
x = 1:c;
xx = 1:faktor:(c+1-faktor);
for i = 1:r
    cs(i,:) = [spline(x,[0 img(i,:) 0],xx),img(i,end)];
end
y = 1:r;
yy = 1:faktor:(r+1-faktor);
for i = 1:(zoom*c)
    us(:,i) = (spline(y,[0 cs(:,i)' 0],yy))';
end
imZoom = cast(us,'uint8');

error = citra_semula - (imZoom);
MSE4 = sum(sum(error .* error)) / (r * c);

set(handles.edit13, 'String', num2str(MSE4));

figure, 
h1=subplot(2,3,1), imshow(citra_semula); title('Citra 512 x 512');
h2=subplot(2,3,2), imshow(g); title('Citra Uji 256 x 256');
h3=subplot(2,3,3), imshow(image_zoom); title('Pembesaran B-Spline I 2x');
h4=subplot(2,3,4), imshow(im_zoom); title('Pembesaran Bicubic 2x');
h5=subplot(2,3,5), imshow(imZoom); title('Pembesaran B-Spline II 2x');

linkaxes([h1,h2,h3,h4,h5])