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getimage

Image data from axes

Syntax

I = getimage(h)
[x,y,I] = getimage(h)
[___,flag] = getimage(h)
[___] = getimage

Description

I = getimage(h) returns the first image data contained in the graphics object h.

[x,y,I] = getimage(h) also returns the image extent in the x and y direction.

[___,flag] = getimage(h) also returns a flag that indicates the type of image that h contains.

example

[___] = getimage returns information for the current axes object.

Examples

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Display image directly from a file using imshow and create a variable in the workspace that contains the image data.

imshow rice.png

I = getimage;

Display image directly from a file using the Image Viewer app (imtool) and create a variable in the workspace that contains the image data.

h = imtool('cameraman.tif');

I = getimage(imgca);

Input Arguments

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Handle to a figure, axes, uipanel, or image graphics object, specified as a handle. If h is an axes or figure handle containing multiple images, then getimage uses the first image returned by findobj(h,'Type','image').

Output Arguments

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Image data, returned as a numeric array. I is identical to the image CData; it contains the same values and is of the same class (uint8, uint16, double, or logical) as the image CData. If h is not an image or does not contain an image, then I is empty.

Image extent in the x direction, returned as a 2-element numeric vector of the form [xmin xmax]. x is identical to the image XData.

Data Types: double

Image extent in the y direction, returned as a 2-element numeric vector of the form [ymin ymax]. y is identical to the image YData.

Data Types: double

Image type, returned as an integer with one of these values:

Flag

Type of Image

0

Not an image; I is returned as an empty matrix

1

Indexed image

2

Intensity image with values in standard range ([0,1] for single and double arrays, [0,255] for uint8 arrays, [0,65535] for uint16 arrays)

3

Intensity data, but not in standard range

4

RGB image

5

Binary image

Data Types: double

Tips

  • For images of data type int16 and single, the image data returned by getimage is of class double, not int16 or single. This is because the getimage function gets the data from the image object's CData property and image objects store int16 and single image data as class double.

    For example, create an image object of class int16. If you retrieve the CData from the object and check its class, it returns double.

    h = imshow(ones(10,'int16')); 
    class(get(h,'CData'))

    Therefore, if you get the image data using the getimage function, the data it returns is also of class double. The flag return value is set to 3.

    [img,flag] = getimage(h);
    class(img)

    The same is true for an image of class single. Getting the CData directly from the image object or by using getimage, the class of the returned data is double.

    h = imshow(ones(10,'single'));
    class(get(h,'CData')) 
    [img,flag] = getimage(h);
    class(img)
  • For images of class single, the flag return value is set to 2 because single and double share the same dynamic range.

See Also

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Introduced before R2006a

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