How can I centre points of interest in an image before it's cropped and saved?

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Teshan Rezel 2020-2-19

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评论： darova 2020-2-19

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Hi folks,

I've successfully managed to crop segmented elements from an image into several images, but I'm now trying to reduce as much of the black background as possible. Below are my code, the base image with the segmented mesh and an example of a cropped section. Any help would be appreciated!

clc; close all;
img = imread('29_11_2019_164105.jpg');
pathName = "C:\Users\ezxtg4\Downloads\JPEG pics\crops\";
[counts, ~] = imhist(rgb2gray(img), 255);
T = otsuthresh(counts);
BW = imbinarize(rgb2gray(img), T);
BW2 = bwareaopen(BW, 3000);
BW2 = imfill(BW2, 'holes');
BW2 = bwperim(BW2);
BW2 = imdilate(BW2, ones(5));
BW2 = imerode(BW2, ones(3));
[L, n] = bwlabel(BW2);
for i = 1:n
    
    I4 = L==i;                      
    I5 = imfill(I4,'holes');    
    I6 = img.*repmat(uint8(I5),[1 1 3]);
    I6 = imclearborder(~I6);
    imwrite(I6, fullfile(pathName, sprintf('crop %d.jpeg', i)));
    
end

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darova 2020-2-19

You want to crop the image or to center?

Teshan Rezel 2020-2-19

sorry I wasn't clear about that! I'd like to perform the former operation, so cropping please

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darova 2020-2-19

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编辑：darova 2020-2-19

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You previous code was ok i think. Just made some changes

[ii,jj] = find(I5);
    % calculate boundaries
i1 = min(ii);       % min row
i2 = max(ii);       % max row
j1 = min(jj);       % min column
j2 = max(jj);       % max column
% ...
I7 = imcrop(I6,[j1 i1 j2-j1 i2-i1]);      % cropped image