How to horizontally extract some region from an image

Hello, i need to extract horizontal region from MRI image shown, to have only the part that located between L4-L5 vertebra. this must be automatically, i mean that when i gave the image to the code; it must strip the upper region (say the 2/3 of the image)

</matlabcentral/answers/uploaded_files/115437/Capture.PNG> exactly like this example which work vertically:

[sana3 sal]

</matlabcentral/answers/uploaded_files/115447/Capture.PNG> this is the image i need to work with

Answer 1

[Wick]

I'm assuming you're not looking to do some sort of image processing to identify where the cutoff should be. With that, here's a snippet of code to extract the lower 1/3 of an image. You can then use the 'imwrite' code to save it as a new image, or use it as you see fit. This bit of code assumes the image size is unknown and simply grabs the bottom third. If you know the exact dimensions and can hard code the rows, by all means do that.

IM = imread('image.png'); % creates an m x n x 3 variable from the data in the image file
subplot(121); image(IM); axis equal; % draw original image just for comparison
s = fix(2/3*size(IM,1)); % finds the two-thirds index for the row. The 'fix' command makes sure it's an integer
IM_small = IM(s:end,:,:); % take only rows from s to the end, all columns, all 3 pages
imwrite(IM_small,'image_small.png','png'); % if you want to write it
subplot(122); image(IM_small); axis equal; % just a plot to see what you've kept.

[sana3 sal]

Thank youuuu! that was very helpful :D