help with calling a function on matlab

Question

Teshan Rezel 2022-8-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783200-help-with-calling-a-function-on-matlab

回答： rumin diao 2022-8-22

Hi folks,

I have the following code but am getting an error when trying to run it! I think it is due to the custom function I have defined but not certain how to get around this.

Below is my code:

i = 1000;
x = im2gray(imread([path, num2str(i), '.png']));
imshow(x);
bw1 = edge(x, 'Sobel');
bw2 = edge(x, 'Prewitt');
bw3 = edge(x, 'Roberts');
bw4 = edge(x, 'log');
bw5 = edge(x, 'zerocross');
bw6 = edge(x, 'Canny');
bw7 = edge(x, 'approxcanny');
t = myMask(bw1);
figure;
subplot(3, 3, 1);imshow(bw1);title('Sobel');
subplot(3, 3, 2);imshow(bw2);title('Prewitt');
subplot(3, 3, 3);imshow(bw3);title('Roberts');
subplot(3, 3, 4);imshow(bw4);title('log');
subplot(3, 3, 5);imshow(bw5);title('zerocross');
subplot(3, 3, 6);imshow(bw6);title('Canny');
subplot(3, 3, 8);imshow(bw7);title('approxcanny');
function test = myMask(bw)
    bw = bwareaopen(bw, 500);
    bw = imfill(bw, 'holes');
    bw = bwperim(bw);
    bw = imdilate(bw, ones(5));
    bw = imerode(bw, ones(3));
    bw = imfill(bw, 'holes');
end

and the error I get it:

Output argument "test" (and maybe others) not assigned during call to "edge detection test>myMask".

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Stephen23 2022-8-22

在 MATLAB Online 中打开

Change the output argument to "bw":

function bw = myMask(bw)
%        ^^

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Answer 1

rumin diao 2022-8-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783200-help-with-calling-a-function-on-matlab#answer_1030350

you defined the function by using 'test = myMask(bw)' which means the function will returns a variable 'test', but in it, you didnt define'test' and there isnt a statement about returning 'test'.

so what you actually need to return is 'bw' and define the function by 'bw = myMask(bw)'