how to get gradient of an image

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Rawan hamdi 2013-3-25

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https://ww2.mathworks.cn/matlabcentral/answers/68511-how-to-get-gradient-of-an-image

移动：DGM 2023-12-29

hi im having a hyperspectral image and im trying to get the gradient operators of the horizontal and vertical directions but i can't any help? Thanks

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Walter Roberson 2013-4-8

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https://ww2.mathworks.cn/matlabcentral/answers/68511-how-to-get-gradient-of-an-image#answer_81534

在 MATLAB Online 中打开

for band = 1 : size(X,3)
  [GX(:,:,band), GY(:,:,band)] = gradient(X(:,:,band));
end

Note you get out two matrices the same size as the original.

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Rawan hamdi 2013-4-9

Thank you very much.

i have a question, how can i obtain the cost function :

u = arg min(||g-u||).^2 + lambda.R(u) where the term "(||g-u||).^2" is the data fidelity term between the original clean image and the noisy image and R(u) is a regularization parameter. Thanks

Walter Roberson 2013-4-9

I recommend you start a new question for that.

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Image Analyst 2013-3-25

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https://ww2.mathworks.cn/matlabcentral/answers/68511-how-to-get-gradient-of-an-image#answer_79812

The Image Processing Toolbox has imgradient() and imgradientxy() functions.

That does not make sense to me. In the lateral x,y direction you have units of "per pixel" but in the Z direction since the planes are different wavelengths, not distance in pixels, the gradient is not a spatial gradient. It would have units of "per wavelength". And you certainly wouldn't want a 3D gradient with spatial coordinates mixed with wavelength coordinates. It makes no sense, at least not to me.

Rawan hamdi 2013-4-8

移动：DGM 2023-12-29

Okay the thing is im that im looping on both x and y and getting the gradient in the spectral domain (z direction) the image i have is [280,307,191] so i'm trying to get the gradient of each pixel in the spectral domain and having the result as a matrix same size of the image,What should i do? Any help would be much appreciated

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