imcrop
Crop image
Syntax
Description
Crop Image Interactively
Note
The interactive syntaxes do not support categorical images. For categorical images,
you must specify the crop region, rect.
Icropped = imcropimcrop returns the cropped image,
Icropped.
With this syntax and the other interactive syntaxes, the Crop Image tool blocks the MATLAB® command line until you complete the operation. For more information about using the Crop Image tool, see Interactive Behavior.
___ = imcrop( creates an
interactive Crop Image tool to crop the image in graphics object
h)h.
Crop Image by Specifying Crop Region
Icropped = imcrop(I,rect)I according to the position and dimensions specified
in the crop rectangle rect. The cropped image includes all pixels in
the input image that are completely or partially enclosed by the
rectangle.
The actual size of the output image does not always correspond exactly with the width
and height specified by rect. For example, suppose
rect is [20 20 40 30], using the default spatial
coordinate system. The upper left corner of the specified rectangle is the center of the
pixel with spatial (x,y) coordinates (20,20). The lower right corner of the rectangle is the
center of the pixel with spatial (x,y) coordinates (60,50). The resulting output image has size 31-by-41
pixels, not 30-by-40 pixels.
Specify Additional Output Options
[___,
also returns the position of the crop rectangle in rectout] = imcrop(___)rectout. You can
use the input arguments of any other syntax.
imcrop(___) without output arguments displays the
cropped image in a new figure window. This syntax does not support categorical
images.
Examples
Read image into the workspace.
I = imread('llama.jpg');Open the Crop Image tool associated with this image. Specify a variable in which to store the cropped image. The example includes the optional return value rect in which imcrop returns the four-element position vector of the rectangle you draw.
[J,rect] = imcrop(I);
When you move the cursor over the image, it changes to a cross-hairs. The Crop Image tool blocks the command line until you complete the operation.
Using the mouse, draw a rectangle over the portion of the image that you want to crop. Perform the crop operation by double-clicking in the crop rectangle or selecting Crop Image on the context menu.
The cropped image appears in the figure window.
The Crop Image tool returns the cropped area in the return variable, J. The variable rect is the four-element position vector describing the crop rectangle you specified. Get information about the returned variables.
whos
Name Size Bytes Class Attributes I 876x1314x3 3453192 uint8 J 413x483x3 598437 uint8 rect 1x4 32 double
Read image into the workspace.
I = imread('circuit.tif');Crop image, specifying crop rectangle.
I2 = imcrop(I,[75 68 130 112]);
Display original image and cropped image.
subplot(1,2,1) imshow(I) title('Original Image') subplot(1,2,2) imshow(I2) title('Cropped Image')
Read and display an image.
I = imread('parkavenue.jpg');
imshow(I)
Specify a target window size as a two-element vector of the form [width, height].
targetSize = [300 600];
Create a Rectangle object that specifies the spatial extent of the crop window.
r = centerCropWindow2d(size(I),targetSize);
Crop the image to the spatial extents. Display the cropped region.
J = imcrop(I,r); imshow(J)
Load an indexed image X with its associated colormap map into the workspace.
load treesCrop the indexed image, specifying the crop rectangle.
X2 = imcrop(X,map,[30 30 50 75]);
Display the original indexed image and the cropped image, both with the colormap.
tiledlayout(1,2) nexttile imshow(X,map) title("Original Image") nexttile imshow(X2,map) title("Cropped Image")
Input Arguments
Output Arguments
More About
The Crop Image tool is a moveable, resizeable rectangle that you can position over the image and perform the crop operation interactively using the mouse.
When the Crop Image tool is active in a figure, the pointer changes to cross hairs
when you move it over the target image. Using the mouse,
you specify the crop rectangle by clicking and dragging the mouse. You can move or resize
the crop rectangle using the mouse. When you are finished sizing and positioning the crop
rectangle, create the cropped image by double-clicking the left mouse button. You can also
choose Crop Image from the context menu. The figure illustrates
the Crop Image tool with the context menu displayed.
| Interactive Behavior | Description |
|---|---|
| Delete the Crop Image tool. | Press Backspace, Escape or Delete, or right-click inside the crop rectangle and select Cancel from the context menu. Note: If you delete the ROI, the function returns empty values. |
| Resize the Crop Image tool. | Select any of the resize handles on the crop rectangle. The pointer changes to a
double-headed arrow  . Click and drag the mouse to resize the crop
rectangle. |
| Move the Crop Image tool. | Move the pointer inside the boundary of the crop rectangle. The pointer changes to a fleur
shape  . Click and drag the mouse to move the rectangle
over the image. |
| Change the color used to display the crop rectangle. | Right-click inside the boundary of the crop rectangle and select Set Color from the context menu. |
| Crop the image. | Double-click the left mouse button or right-click inside the boundary of the crop rectangle and select Crop Image from the context menu. |
| Retrieve the coordinates of the crop rectangle. | Right-click inside the boundary of the crop rectangle and select Copy
Position from the context menu. imcrop copies a
4-element position vector ([xmin ymin width height]) to the
clipboard. |
