How to measure the mean contrast of edge pixels?

I need to find the mean contrast of edge pixels and standard deviation of edge pixels.

I came across this definition but I didn't understand that

where A is the 8 neighboring pixels of current pixel with high intensity and B is the remaining 8 neighboring pixels of the A, numA is the number of pixels in A.

Can somebody help me in implementing this?

Thank you.

[KALYAN ACHARJYA]

Is it edge boundary or edges within the image?

[Krishna Chaitanya]

There are some white regions within a binary image and I have to find the mean contrast for every such white region in the image.

I don't know whether it is edge boundary or edges within the image.

Answer 1

[KALYAN ACHARJYA]

image is a gray scale image.

th=128; %considering unit8 image having range 0-255, you can decide or calculate 
data=image>=th;
data1=uint8(data).*image;
imag_high=sum(data1(:))/sum(data(:));
data2=uint8(~data).*image;
image_low=sum(data2(:))/sum(~data(:));
c=imag_high-image_low;

[Krishna Chaitanya]

can you please explain me what 'th' is and what exactly is the code doing?

th> Threshold value gray to binary