Identifying an object and its centroid in an image and then cropping the original image based on this centroid

Question

Sam 2021-9-29

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https://ww2.mathworks.cn/matlabcentral/answers/1463419-identifying-an-object-and-its-centroid-in-an-image-and-then-cropping-the-original-image-based-on-thi

评论： Dayangku Nur Faizah Pengiran Mohamad 2024-5-19

gas-x-summer-fruits-cause-bloating-main.jpg

Hello,

I need to detect a particular objects out of many objects in an image. Then I need to find its centroid and then crop the image around that particular tracked object using its centroid as the centre of that rectangular crop.

For example, let's say I need to idenfity the marked watermelon piece (as in the attached picture) and then crop the image around this piece of watermelon.

Any help in this regard will be greatly appreciated. Thank you very much!

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Answer 1

yanqi liu 2021-9-30

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https://ww2.mathworks.cn/matlabcentral/answers/1463419-identifying-an-object-and-its-centroid-in-an-image-and-then-cropping-the-original-image-based-on-thi#answer_798454

在 MATLAB Online 中打开

sir，please check the follow code to get some information

for more information,you can read the book 《计算机视觉与深度学习实战》，Thank you！

clc; clear all; close all;

img = imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/753699/gas-x-summer-fruits-cause-bloating-main.jpg');

% colorspace

jmg = rgb2ycbcr(img);

jm = mat2gray(jmg(:,:,2));

jm = imcomplement(jm);

% thresh

bw = im2bw(jm, graythresh(jm));

% filter noise

bw = imopen(bw, strel('disk', 5));

bw = imfill(bw, 'holes');

% label every target

[L,num] = bwlabel(bw);

stats = regionprops(L);

figure; imshow(img, []);

for i = 1 : num

% get rect

recti = stats(i).BoundingBox;

% get cen

ceni = stats(i).Centroid;

% crop image

imi = imcrop(img, round(recti));

ims{i} = imi;

% rect and cen

hold on; rectangle('Position', recti, 'EdgeColor', 'c', 'LineWidth', 2);

plot(ceni(1), ceni(2), 'yp', 'MarkerFaceColor', 'y', 'MarkerSize', 16);

end

% make grid

sz = round(sqrt(length(ims)));

if sz*sz < length(ims)

sz = [sz+1 sz];

else

sz = [sz sz];

end

figure;

montage(ims, 'Size', sz, 'BackgroundColor', 'w', 'BorderSize', [3 3])

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Sam 2021-10-7

Hi,

Thanks for your comment!

I am working on vehicle detection by extracting frames from overhead drone videos. Here, I am trying to track a particular vehicle and crop the bigger image around that tracked vehicle.

For example, attached image 1 is the full size extracted image from the video, and I want to identifiy all the vehicles in this image (if possible). Then dectecting the white car (highlighted in image 2) and cropping the image around it.

It will be very helpful if you can give my some advice in this regard.

Dayangku Nur Faizah Pengiran Mohamad 2024-5-19