error in executing loop

    I have a code for compression below,but my image is not compressed instead the size is more than the original folder

    pathname ='F:\mri\' 
     dirlist = dir( [pathname '*.jpg'] );
     pickind='jpg';

    for m = 1:length(dirlist)
      map = pink(90);

        I = imread([pathname, dirlist(m).name]);

    [R1 C1]=size(I)

    x=size(I)    

     for i=2:2:x(1)
       for j=3:2:x(2)

             H1(i,j)=I(i,j);

       end
    end
    H1;

    for i=2:2:x(1)

        for j=2:2:x(2)

            H2(i,j)=I(i,j);

        end
    end
    H2;
    size(H1)
    size(H2)
    [R12 C12]=size(H1);
    [R13 C13]=size(H2);
    R12
    C12
    R13
    C13
    Z1=C1-C12
    if R1-R12~=0

        a=zeros((R1-R12),C1)
        H1=[H1;a];

    else if Z1>0

            b=zeros(R1,Z1)
           L= size(b)
            H17=[H1 b];

        end
    end
    size(H17)

    if R1-R13~=0

        a=zeros((R1-R13),C1)
        H2=[H2;a];

    else if C1-C13~=0

            b=zeros(R1,(C1-C13))
            H2=[H2 b];

        end
    end
    size(H2)
    H=H17-H2;

    pickind='jpg'

    singvals=20 ;

        a=H;
        dvalue=double(a);

         [u,s,v] = svds(dvalue, singvals);
        if isa(a,'uint8')
            im = uint8(u * s * transpose(v));

        elseif isa(a,'uint16')
            im = uint16(u * s * transpose(v));
        %end

        elseif isa(a,'double')
        im = (u * s * transpose(v));
        else  im = (u * s * transpose(v));
        end
        strtemp=strcat('F:\ehs\',int2str(m),'.',pickind);  
    imwrite(im,strtemp);%title('ebcot low pass frames ');
    end

The size of mri folder is 170kb(15 images)

but in folder ehs the size is 193kb,(15 images),please tell ehy my image is not compressed