Get image handle with imshow

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Lask 2017-10-19

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https://ww2.mathworks.cn/matlabcentral/answers/362120-get-image-handle-with-imshow

编辑： Stephen23 2017-10-19

When I create a white image and try to access its handle via imshow, it returns a number instead of a struct.

% Create vector white image
img = 255 * ones(600, 600, 3, 'uint8');
% Get handle of the image
handle = imshow(img);

Typing 'handle' returns 174.0011 instead of a struct containing image properties. Why is this happening? I'm working with MATLAB 2014a

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Lask 2017-10-19

在 MATLAB Online 中打开

So how would I change the image data so I can transform it into a black image? I was using

handle.CData = zeros(600, 600, 3, 'uint8');

in MATLAB 2014b, but what's the way in 2014A?

Stephen23 2017-10-19

编辑：Stephen23 2017-10-19

Just like I wrote in my answer: use set and get to access or change the properties of any graphicsw object. Note that set and get work with all versions of MATLAB (with graphics handles).

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Answer 1

Stephen23 2017-10-19

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https://ww2.mathworks.cn/matlabcentral/answers/362120-get-image-handle-with-imshow#answer_286598

编辑：Stephen23 2017-10-19

"Why is this happening?"

Because that is exactly what your version of MATLAB does. All graphics handles prior to R2014b are numeric values, so what you are seeing is entirely the expected behavior. You can access and change any properties using set and get. You can read about the changes introduced in R2014b here:

https://www.mathworks.com/products/matlab/matlab-graphics.html

and in plenty of detail about the handles here:

https://www.mathworks.com/help/matlab/graphics_transition/graphics-handles-are-now-objects-not-doubles.html

and here:

https://blogs.mathworks.com/loren/2014/10/14/matlab-r2014b-graphics-part-2-using-graphics-objects/

Note that the blog also explains how numeric handles (pre-R2014b) work!

"... it returns a number instead of a struct."

Graphics handles R2014b and later are objects of a specific graphics class. They are not structs.