How to select and crop a particular region from the image?

After some filtering, I manage to get this image,

My question is, how do you select and hopefully crop the region of interest? So I can get something like this.

Many thanks,

Answer 1

[blaat]

If you have the Image Processing Toolbox, you can use the function imrect() to select a rectangular area from your image. For example:

figure;
imshow(img);
h_rect = imrect();

% Rectangle position is given as [xmin, ymin, width, height]
pos_rect = h_rect.getPosition();

% Round off so the coordinates can be used as indices
pos_rect = round(pos_rect);

% Select part of the image
img_cropped = img(pos_rect(2) + (0:pos_rect(4)), pos_rect(1) + (0:pos_rect(3)));

[piku mandal]

but how to use it for live images that is come from camera?

[Jessica Avellaneda]

how to use it for a movie?

Answer 2

[Josep Llobet]

You can select just the regions of the matrix that define your image, as follows:

img_cropped = img(300:450, 500:600);
imshow(img_cropped)

In the example, you will select the image in the regions between 300 and 450 of the x axis, and the 500 to 600 in the y axis.

If you want to know the size of the matrix which define your image, you can use size()

size(img)

Hope this will be useful!!