Calculating the distance between two matrices Matlab

I want to calculate the distance between two different DFT results after i performed this code:

I1 = imread('sample1');%read the images
I2 = imread('sample2');

GI1 = rgb2gray(I1) %change it to grayscale
GI2 = rgb2gray(I2)

DftR1 = DFT(GI1) %perform the 2-dimensional DFT(a function that i built it myself)
DftR2 = DFT(GI2)

so far it all worked; however when i want to compare the results of the DFT using this code:

Distance = pdist2(DftR1, DftR2)

I get this particular error: Error using pdist2 (line 224) PDIST2 does not accept complex data for built-in distances.

Answer 1

[Star Strider]

The DFT that the code you posted previously returns will be complex.

If pdist2 wants only real values,

Distance = pdist2(abs(DftR1), abs(DftR2));

will likely work.

[alladin]

Thank you, it worked, but the issue that the result was a matrix, i thought by calculating the distance i will get only one value so that i can tell whether the results match or not.

If you have an idea on how to do it please let me know. I appreciate your help

[Star Strider]

My pleasure.

The pdist2 function returns a matrix by definition. You can force the matrix to become only value by creating a vector out of it and then performing the operation you believe best suits your application. The mean or standard deviation might be most appropriate:

Dmean = mean(Distance(:));
Dstdv = std(Distance(:));

[alladin]

I appreciate your help thank you

Answer 2

[Deepesh B]

Hi U have to use

abs

before applying

pdist2

because after fft it will have complex numbers