Why the values of perimeter calculated using regionprops for Matlab 2010 and 2015 differ?

Question

Waleed Saqib 2015-5-22

编辑： Waleed Saqib 2015-5-28

The following code

a=zeros(5)
a(2,2)=1
a(2,3)=1
f=regionprops(a,'Perimeter')

when executed on Matlab 2010 , gives 2 as the value of perimeter.

But when I execute the same code on Matlab 2015 , the perimeter is 1.96.

Can anyone explain what is the reason of this difference.

For the record, Matlab 2010 is not rounding off the value.

Secondly, how regionprops calculate perimeter of an object in an image. I have read the help of this command but was unable to comprehend the method.

Answer 1

Ashish Uthama 2015-5-26

The release notes R2014a appears to explain that the newer value is more accurate.

Waleed Saqib 2015-5-28

编辑：Waleed Saqib 2015-5-28

Thank you so much for your help. It really helped a lot.

Can you also explain how perimeter is calculated by Matlab? I mean how the distance is computed between two pixels.