How can I crop the image at a particular location each time?

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I have multiple rbg images. I want to analyze them for pixel calculation. But I only want a part of it. How can I crop all the images at the exact same location?

Accepted Answer

yanqi liu
yanqi liu on 9 Feb 2022
yes,sir,just use imcrop can get target area image,if multi image do not have same size,may be use width and height rate,such as
clc; clear all; close all;
files = {'cameraman.tif', 'football.jpg', 'rice.png'};
rect = [0.2 0.3 0.4 0.3];
for i = 1 : length(files)
% get image
imi = imread(files{i});
sz = size(imi);
% get rect
recti = rect .* [sz(2) sz(1) sz(2) sz(1)];
% crop image
imi2 = imcrop(imi, round(recti));
figure;
subplot(1,2,1); imshow(imi, []);
hold on; rectangle('position', recti, 'EdgeColor', 'r', 'LineWidth', 2)
subplot(1,2,2); imshow(imi2, []);
end

More Answers (2)

Highphi
Highphi on 8 Feb 2022
Your rgb images are an X x Y x 3 array,
where, visually, X is actually image height and Y is actually image width
If you imaging that the top left corner of your image is 0,0
you can get another smaller cropped area via:
rgb2 = rgb1(X1:X2, Y1:Y2, :);

David Hill
David Hill on 8 Feb 2022
Edited: David Hill on 8 Feb 2022
Your rbg image is just a matrix. Just index into the matrix at the location you want.
x=uint8(randi(255,1000,1000,3));
imshow(x(10:10,50:80,:));

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