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how to extract horizontal and vertical garadients of image.

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pankaj chouthmal
pankaj chouthmal on 27 Jan 2014
Commented: Image Analyst on 29 Jan 2014
What is mean by horizontal and vertical gradients ? Suppose if we have 41*41 matrix or image, then how we can compute its horizontal and vertical gradients ?

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Answers (3)

Anthony
Anthony on 27 Jan 2014
Hi,
You can use the diff function. Let img be your image :
img = spiral(10); % For example
gradX = diff(img,1,1);
gradY = diff(img,1,2);
doc diff
Hope it helps,
Anthony

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Image Analyst
Image Analyst on 27 Jan 2014
You can imgradientxy)() in the Image Processing Toolbox. From the help:
I = imread('coins.png');
[Gx, Gy] = imgradientxy(I,'prewitt');
figure
imshowpair(Gx, Gy, 'montage');
title('Directional Gradients: x-direction, Gx (left), y-direction, Gy (right), using Prewitt method')
axis off;

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pankaj chouthmal
pankaj chouthmal on 29 Jan 2014
i have used both above methods to calculate image gradients but both answers are totally different . which one is more appropriate ?

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Image Analyst
Image Analyst on 29 Jan 2014
The one that gets the job done for you. I don't really care as long as it works.

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