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crop

Create cropped version of blocked image

Since R2021a

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Syntax

cbim = crop(bim,cstart,cend)

Description

cbim = crop(bim,cstart,cend) crops the blocked image bim to the crop window specified by the starting and ending pixel subscripts cstart and cend, inclusive. Returns cbim, a blockedImage which references the same Source as bim, but represents image data in the crop window, across all levels.

example

Examples

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Open Live Script

Create a blocked image from a sample image included with the toolbox.

bim = blockedImage('tumor_091R.tif');
figure
bigimageshow(bim);

Inspect image size and world coordinate properties

bim.Size
ans = 3×3

        5000        5358           3
        1250        1340           3
         625         670           3


bim.WorldStart
ans = 3×3

    0.5000    0.5000    0.5000
    0.5000    0.5000    0.5000
    0.5000    0.5000    0.5000


bim.WorldEnd
ans = 3×3
103 ×

    5.0005    5.3585    0.0035
    5.0005    5.3585    0.0035
    5.0005    5.3585    0.0035

Define a region of interest on the image that will be the crop area.

hrect = drawrectangle('Position', [2280 1300 1024 800]);

Figure contains an axes object. The axes object contains 2 objects of type bigimageshow, images.roi.rectangle.

Obtain the world coordinates of the region.

wstartxy = hrect.Position(1:2);
wendxy = wstartxy + hrect.Position(3:4);

Convert to row-col order, include world coordinates of the last dimension.

wstart = [wstartxy(2), wstartxy(1), bim.WorldStart(1,3)];
wend   = [wendxy(2), wendxy(1), bim.WorldEnd(1,3)];

Convert to image subscripts, this is an optional step useful when using non-default world coordinates.

subs = world2sub(bim, [wstart; wend]);
cbim = crop(bim, subs(1,:), subs(2,:));

Inspect properties of the cropped image.

cbim.Size
ans = 3×3

         801        1025           3
         201         258           3
         101         130           3


cbim.WorldStart
ans = 3×3
103 ×

    1.2995    2.2795    0.0005
    1.2965    2.2757    0.0005
    1.2965    2.2717    0.0005


figure
% Axes limits reflect cropped coordinates
bigimageshow(cbim);

Figure contains an axes object. The axes object contains an object of type bigimageshow.

Input Arguments

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Blocked image, specified as a blockedImage object.

First pixel in the crop window, in pixel subscripts, specified as a 1-by-N integer-valued vector for an N-dimensional blockedImage. If cstart has fewer than N elements, blockedImage extends it with 1s.

Last pixel in the crop window, in pixel subscripts, specified as a 1-by-N integer-valued vector. If cend has fewer than N elements, blockedImage extends the image with the corresponding elements from Size at the finest level.

Output Arguments

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Cropped blocked image, returned as a blockedImage object that contains image data in the crop window across all resolution levels.

Version History

Introduced in R2021a

See Also