Subscript indices must either be real positive integers or logicals?

Why did i get this error?

ref = imread('TID2008\reference_images\I01.BMP');
A = imread('TID2008\distorted_images\I01_01_1.bmp');
peaksnr = psnr(A, ref);

Subscript indices must either be real positive integers or logicals

[KSSV]

What is class of ref and A?

Answer 1

[Jan]

A bold guess: You have redefined one of the used symbols "imread" or "psnr" by an array. Check this:

which imread -all
which psnr -all

If one of does not reply the wanted function on top, use clear to remove the shadowing array and use a different name for it.

Note that it would be useful, if you post a copy of the complete error message. This would narrow down the possible number of problems.