image cropping location problem

why i got diffrent location of crop when i change the image im using btw im using the same value of coordinate but the location is diffrent

[KALYAN ACHARJYA]

Can you more specific please?

[MOHAMED GILANI]

im working on diffrent set of image and i need to specife or crop a certen region in thees images but when i set the coordinate of the targeted location it miss with the other images

[KALYAN ACHARJYA]

May be target regions are not same spatial postion in all co-ordinates? Because the image capturing system movement or object movement, more, there can be many reasons for this.

[MOHAMED GILANI]

its a MRI image

do u think?

[Walter Roberson]

Movement is possible within an MRI. Depending on the instrument, it might be necessary to do image registration between slices.

I suggest that you take two slices that appear to be cropped differently, and use imshowpair() . That will highlight the differences in the slices. If the slices are different Z panes within the same organ, then you would expect some differences, but the images would be expected to have the same centers. If imshowpair() gives the impression that the images are not aligned, then you might need image registration.

[DGM]

Provide a simplified and concrete example demonstrating the problem.

[Matt J]

Maybe the images are not all the same size. Therefore, the cropping coordinates don't cover the same spatial region in all cases.

Answer 1

[yanqi liu]

sir，may be use the rate，such as

clc; clear all; close all;
im = imread('cameraman.tif');
sz = [size(im, 1) size(im, 2)];
rect = round([sz(2)/2 sz(1)/2 sz(2)*0.2 sz(1)*0.3]);
im2 = imcrop(im, rect);
figure;
subplot(1, 2, 1); imshow(im);
hold on; rectangle('position', rect, 'EdgeColor', 'g', 'LineWidth', 2)
subplot(1, 2, 2); imshow(im2);

im = imread('football.jpg');
sz = [size(im, 1) size(im, 2)];
rect = round([sz(2)/2 sz(1)/2 sz(2)*0.2 sz(1)*0.3]);
im2 = imcrop(im, rect);
figure;
subplot(1, 2, 1); imshow(im);
hold on; rectangle('position', rect, 'EdgeColor', 'g', 'LineWidth', 2)
subplot(1, 2, 2); imshow(im2);