# How to extract the main square, image window of the ultrasound image?

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Stelios Fanourakis 2019 年 9 月 27 日
Hi
I need some help.
How do I extract/crop the main square of the ultrasound image. The image window that shows the valuable information and discard all the rest black and annotations.
Looking forward to your valuable help
Thanks

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### 採用された回答

Constantino Carlos Reyes-Aldasoro 2019 年 9 月 27 日
Ok, the issue here is the colour maps and the conversion of uint8 to double. If you convert to double the colours are always between 0 and 1, so you would need to divide by the maximum value (in this case 255)
imagesc(double(A6__14_9N_).*(repmat(1-(background),[1 1 3]))/255)
OR you can convert to uint8 the background:
imagesc(A6__14_9N_.*(repmat(1-uint8(background),[1 1 3])))
Both should work.
##### 2 件のコメント表示非表示 1 件の古いコメント
Constantino Carlos Reyes-Aldasoro 2019 年 9 月 27 日
Ok, that is a bit different. You basically need to find the limits of rows and columns. Find the complement of the background
(1-background)
and sum over the columns and rows
sum( ,1)
sum( ,2)
That would generate 1D vectors where the foreground exist. The use the function "find" and select the first non-zero element (that will give you the first row/column) and the last (final row/column) and with that you can crop into a new matrix.

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### その他の回答 (2 件)

Constantino Carlos Reyes-Aldasoro 2019 年 9 月 27 日
Hard to answer without knowing your data. Post a sample and we can try.
##### 1 件のコメント表示非表示 なし
Stelios Fanourakis 2019 年 9 月 27 日
See attached image. Thanks

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Constantino Carlos Reyes-Aldasoro 2019 年 9 月 27 日
*IF* all the images look like this, it is rather easy, EXCEPT for the fact that the bottom edge of the ultrasound is not very well defined.
The key is to find the background to determine the foreground, The background is black, so take only one channel (the image is RGB), compare against zero and that would give the background but with the annotations and bits you want to remove, so close the image with imclose with a structural element sufficiently large to cover those elements:
background =(imclose(A6__14_9N_(:,:,1)==0,ones(25)));
Then, you only need to take the complement and recover the ultrasound part
imagesc(A6__14_9N_.*(repmat(1-background,[1 1 3])))
If you compare with the original, it seems that the job is done.
##### 5 件のコメント表示非表示 4 件の古いコメント
Stelios Fanourakis 2019 年 9 月 27 日
Did you convert it from .bmp to other format?

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