dwt2 function for image compression

Hello, I'm supposed to use the following code for a project to transform the image "WeeksHallSmall.jpg", but I am so confused as to what I am supposed to input for X. I don't know if I need both imread and load as well. I am confused on where I need to add additional inputs, rather than what the MATLAB documentation supplied.

imread("WeeksHallSmall.jpg");

load 'WeeksHallSmall.jpg'

imagesc(X)

colormap gray

[LoD,HiD] = wfilters('haar','d');

[cA,cH,cV,cD] = dwt2(X,LoD,HiD,'mode','symh');

subplot(2,2,1)

imagesc(cA)

colormap gray

title('Approximation')

subplot(2,2,2)

imagesc(cH)

colormap gray

title('Horizontal')

subplot(2,2,3)

imagesc(cV)

colormap gray

title('Vertical')

subplot(2,2,4)

imagesc(cD)

colormap gray

title('Diagonal')

Answer 1

[Harsh Sanghai]

Hello Izabela,

For reading and displaying your own custom image "WeeksHallSmall.jpg" you can use the below code:

z = imread("WeeksHallSmall.jpg");
imagesc(z);

Note: imagesc(X) displays the data in array X as an image that uses the full range of colors in the colormap.

For understanding the "load" command use the below documentation as it is used to load ".mat" files:

Load variables from file into workspace - MATLAB load (mathworks.com)

For more information on dwt2 refer the documentation below:

dwt2 - Search - Help Center - MATLAB & Simulink (mathworks.com)