Matlab image processing thresholding and implementing an equation in matlab

Using equation P=(8/(i2-i1))*∑grad(i) to find a threshold where i1=0.1% i2=10% of total length of pixel indices. How do I implement this equ in matlab and what does i1,i2 mean and how can i find their value? How can i find the divergence of an image?

Answer 1

[Image Analyst]

Compute the cdf

[counts, bins] = histcounts(data);
theCDF = cumsum(counts);
theCDF = theCDF / theCDF(end);
i1 = find(theCDF > 0.001, 1, 'first');
i2 = find(theCDF > 0.1, 1, 'first');

[Nasser Jarrar]

I'm supposed to upload an image and process the function "histcounts" won't work with uint8. To be more clear I've uploaded the paper and the alogrithm i want to implement.

[Nasser Jarrar]

Here's the paper.