Question

This is what i am trying to do in MATLAB but can’t seem to get around achieving it

For each row in the filtered image, assign a value
of one to the pixels that have the minimum value
in that row and the other pixels to zero

Answer 1

Here’s a solution:

img = imread('https://i.stack.imgur.com/tY3YE.jpg');
img = rgb2gray(img); %# transform jpeg color image to grayscale

minValue = min(img,[],2);
%# set the pixels equal to the minimum value to 1
bw = bsxfun(@eq,img,minValue);

When I run this on the image you linked, I get

Which shows that there are plenty of border effects from median filtering. Removing the border 10 pixels, i.e. with

img = img(10:end-9,10:end-9);

and running the code again, I find

Which makes quite a bit more sense.