Hi fadmas18,
I understand that you are trying to find the relative error between 2 images using MATLAB’s “norm” function inside your custom-made function “norm_fro”.
When running the provided code, I too faced a similar error. This error occurs because the input images provided, “X” and “Xhat” are 3D arrays (300×300×3 for RGB), while the norm function with the “fro” option expects a 2D matrix. To resolve this, you need to reshape the images into 2D matrices before applying the Frobenius norm.
Kindly refer to the following corrected code:
function f = norm_fro(X, Xhat)
% Reshape 3D image into 2D matrix
X = reshape(X, [], size(X, 3));
Xhat = reshape(Xhat, [], size(Xhat, 3));
% Compute Frobenius norm
f = norm(X - Xhat, 'fro')^2 / norm(X, 'fro')^2;
end
The command “reshape(X, [], size(X, 3))” changes the 300×300×3 image into a 90000×3 matrix, making it compatible with the “norm” function. This method enables the correct computation of the Frobenius norm for the 2D representation. With this adjustment, the "Input must be 2-D" error is fixed, allowing for an accurate calculation of the relative error.
For further reference on the “norm” function in MATLAB, kindly refer to the below documentation:
Cheers & Happy Coding!
