Hi Nishtha,
Decomposition of image into LL and HH subbands can be done using the ‘dwt2’ function present in MATLAB. To perform the decomposition you can perform the following steps:
- Load the image.
- Convert the image to grayscale.
- Perform wavelet decomposition.
- Extract the LL and HH sub bands from the decomposition.
Below is a MATLAB example on how to perform a 2D wavelet decomposition using the ‘dwt2’ function.
% load the image and convert it to grayscale
image = imread('cameraman.tif');
grayImage = im2gray(image)
% perform wavelet decomposition using the dwt2 function
[LL1,LH1,HL1,HH1]=dwt2(grayImage,'db1');
[LL2,LH2,HL2,HH2]=dwt2(LL1,'db1');
[LL3,LH3,HL3,HH3]=dwt2(LL2,'db1');
% Display the original image and the subbands
figure;
subplot(1, 3, 1);
imshow(image);
title('Original Image');
subplot(1, 3, 2);
imshow(LL1, []);
title('LL Subband');
subplot(1, 3, 3);
imshow(HH1, []);
title('HH Subband');
The above code gives the following output:
For more information regarding the functions used and some other examples, you can refer to the following resources:
- dwt2: https://www.mathworks.com/help/wavelet/ref/dwt2.html
- LL,LH,HL,HH decomposition: https://www.mathworks.com/matlabcentral/answers/634054-what-are-ll-lh-hl-hh-in-dwt
- MATLAB code for third level DWT: https://www.mathworks.com/matlabcentral/answers/163844-how-to-write-matlab-code-for-third-level-dwt
