i am getting a straight black line when i want to see the LL subband of the image. what to do to see the LL subband image after DWT

code i am executing is\close all; clear all; imData=imread('lena256.bmp'); imshow(imData); title('Original image'); pause(2); map=gray(256);

n=1:256; x=sin((pi/64)*n)+0.01*(n-100);

[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('bior5.5'); [N, M]=size(imData); % dwt in row dwt_row_image=zeros(N, M); tmpData=zeros(1, M); for i=1:N tmpData(1, 1:M)=imData(i, 1:M); tmpData(1, 1:M)=dwt(tmpData, Lo_R); dwt_row_image(i, 1:M)=tmpData(1, 1:M); end tmpData=zeros(1, N); dwt1_imData=zeros(N, M); for i=1:M tmpData(1, 1:N)=dwt_row_image(1:N, i)'; tmpData(1, 1:N)=dwt(tmpData, Lo_R); dwt1_imData(1:N, i)=tmpData(1, 1:N)'; end

figure(2); imshow(dwt1_imData, map); title(' After DWT');

imshow(Lo_D);

[Image Analyst]

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