crop a region of interest on images and create new files only with this region
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Anastasia
am 8 Mär. 2016
Kommentiert: Image Analyst
am 3 Apr. 2016
Dear all,
I am writing to you because I am new to Matlab and I would be very grateful if you could help me. I have images from 20 sections from t=0 to t=70 (which would make for 1420 images, beginning with z0000_t0000, z0001_t0000... leading up to z00019_t0069, size of the field 200x200, pixels 521x512), that I normally put into Z-stack and analyse over time with ImageJ. However, I would like to have a Matlab program that would extract only one region of the image (that I would choose, either draw manually or by establishing coordinates, but I have no idea how establish the coordinates?) and create 1420 images (either new 1420 images, or transform the original image into images with the ROI) only with that region. Is it possible, and could you please help me do it? Thank you very much.
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MHN
am 9 Mär. 2016
Bearbeitet: MHN
am 9 Mär. 2016
Im = imread('ngc6543a.jpg'); %load your image
image(Im)
x_start = 50; % start x
x_end = 500; % end x
y_start = 50; % start y
y_end = 500; % end x
Im1 = Im([x_start:x_end],[y_start:y_end],:);
figure
image(Im1)
imwrite(Im1,'newimage.jpg') % save the croped image
To find your coordinates, you can see the original picture (Im), use the "data cursor" and you can find your min\max x and min\max y.
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Weitere Antworten (2)
Anastasia
am 9 Mär. 2016
3 Kommentare
Image Analyst
am 12 Mär. 2016
You have to process them one by one, but you can put the processing into a loop so that it's essentially a batch process. Code for this is in the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F
MHN
am 12 Mär. 2016
If I want to integrate the answers (Just save the following code in the same path as your image's files):
for i = 0 : 19;
for j = 0 : 69;
filename = ['z00' sprintf('%02d',i) '_t00' sprintf('%02d',j) '.jpg'];
Im = imread(filename);
x_start = 50; % start x
x_end = 500; % end x
y_start = 50; % start y
y_end = 500; % end x
Im_new = Im([x_start:x_end],[y_start:y_end],:);
imwrite(Im_new, filename) % replace the croped image
end
end
Anastasia
am 3 Apr. 2016
1 Kommentar
Image Analyst
am 3 Apr. 2016
Be very careful when using MHN's code because he made the common mistake of swapping x and y.
Images are arrays, and are indexed like arrays as (row, column), NOT (x,y) as he had. You will need to swap all of his x,y with y,x to get his code to work properly.
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