Thank you for your reply, I tried using bandpower function but it shooting me following error. Can you please let me know how to reslove it. My sampling is of 0.1 pixels and and range in power spectrum is from [-5 5]. I will appreciate your help.
b = bandpower(nps_measured,5,[-5 5]);
Error using bandpower>psdbandpower (line 127)
The frequency range must be within the range of F for the specified input.