bi_linear.m

[matlab] DIP nearest neighbor interpolation and bilinear interploation

function bi_linear(img,a)
A=double(img);
[ar_size,ac_size]=size(A);
B=zeros(a.*size(A));
[br_size,bc_size]=size(B);

for i=1:br_size
    for j=1:bc_size
        x0=i/a;
        y0=j/a;
        x=fix(i/a);
        y=fix(j/a);
        x1=x+1;
        y1=y+1;
        if x==0
            x=1;
        end
        if y==0
            y=1;
        end
    if a>1
        if x >= ar_size
            x1=ar_size;
        end 
        if y >= ac_size
            y1=ac_size;
        end
    end
    if a<1
        if x >= br_size
            x1=br_size;
        end 
        if y >= bc_size
            y1=bc_size;
        end
    end
        f1=A(x,y)+(x0-x).*[A(x1,y)-A(x,y)];
        f2=A(x,y1)+(x0-x).*[A(x1,y1)-A(x,y1)];
        B(i,j)=f1+(y0-y).*(f2-f1);
    end 
end
imshow(uint8(B));
size(A)
size(B)
imwrite(uint8(B),'d:\pic\result.jpg','jpg');