Create an error function

Hi,

I have 2 matrices of images, with all values 0 and 1. I would like to compare the two, where i would like to get the number of true positives (where both pixels -at the same postion- are equal to 1), true negatives (both pixels equal to 0), false positives ( where image A is equal to 1 but image B is equl to 0) and false negatives (where image A is equal to 0 but image B is equal to 1).

If I try to extract where A==1 and B==1 etc. and compare it, I get an error because the matrices dont agree.

If I just compare A to B I only get where the match/not match but it doesnt tell me if its a true positive etc.

thank you

[KSSV]

YOu can use :

idx = A == B ; 

Apply your formula on matrix idx.

[udi ibgui]

What do you mean by apply formula?

The above code shows 1 whenever they match and 0 whenever they dont. It doesnt tell me if the match was becasue they were both 1 or both 0

Answer 1

[munue]

You can try the following:

A=[1 0; 0 1]

B=[1 0 ; 1 0]

TruePositive_idx = find (A==B & A==1)

TrueNegative_idx = find (A==B & A==0)

FalseNegative_idx = find (A~=B & A==1)

FalsePositive_idx = find (A~=B & A==0)