MATLAB Answers

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

2 views (last 30 days)
Teshan Rezel on 19 Feb 2020
Commented: darova on 19 Feb 2020
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
##### 4 CommentsShowHide 3 older comments
Teshan Rezel on 19 Feb 2020
sorry I wasn't clear about that! I'd like to perform the former operation, so cropping please

Sign in to comment.

### Accepted Answer

darova on 19 Feb 2020
Edited: darova on 19 Feb 2020
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
EDITED: made a mistake in imcrop(I,[xmin ymin width height])
##### 2 CommentsShowHide 1 older comment
darova on 19 Feb 2020
Made a mistake. Look at the script

Sign in to comment.

R2019b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!