How to calculate gradient features of an image?

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Maninder 2014-10-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159610-how-to-calculate-gradient-features-of-an-image

评论： Munshida P 2019-8-25

My code is:

 a = imread('C:\Users\DELL\Desktop\01_test.tif');
 [Gx, Gy] = gradient(a);
 [Gmag, Gdir] = gradient(Gx, Gy);
 figure, imshow(Gmag, []), title('Gradient magnitude') figure, imshow(Gdir, []), title('Gradient direction') title('Gradient Magnitude (Gmag) and Gradient Direction (Gdir) using Sobel method') figure; imshowpair(Gx, Gy, 'montage'); axis off; title('Directional Gradients, Gx and Gy, using Sobel method') 

error is:

??? Error using ==> rdivide Integers can only be combined with integers of the same class, or scalar doubles.

Error in ==> gradient at 75 g(2:n-1,:) = (f(3:n,:)-f(1:n-2,:))./h(:,ones(p,1));

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Guillaume 2014-10-22

Please use the {} Code button to format your code.

And what is your question exactly?

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回答（2 个）

Guillaume 2014-10-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159610-how-to-calculate-gradient-features-of-an-image#answer_156136

在 MATLAB Online 中打开

Possibly, you meant to use imgradient or imgradientxy.

You left out the important bit of the error, which is the one that told you on which line of your code the error occurred. I assume it's the

[Gmag, Gdir] = gradient(Gx, Gy);

line that gives you the error, since the 2nd argument to gradient must be a scalar value.

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Munshida P 2019-8-25

how to calulate the average gradient ?

i have calculated Gx,Gy,Gmag,Gdir

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Munshida P 2019-8-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/159610-how-to-calculate-gradient-features-of-an-image#answer_388902

how to calculate average gradient of an image

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Walter Roberson 2019-8-25

在 MATLAB Online 中打开

[Gmag, Gdir] = imgradient(YourGrayscaleImage, 'prewitt');
average_gradient = sum(double(Gmag(:))) ./ ((size(Gmag,1)-1) .* ((size(Gmag,2)-1).*sqrt(2));