Radial gradient of grayscale image

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Christoph 2013-2-5

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https://ww2.mathworks.cn/matlabcentral/answers/62326-radial-gradient-of-grayscale-image

Hey guys, it is me again with my image problems. ;)

I have a grayscale image and I would like to calculate the radial gradient of this image so I can look for extremums in the gradient and detect some features.

Previously I did this in a linear manner, eg take the next and previous pixel, divide their difference by 7 and get the 7-pixel gradient, but now I am struggling to do something similar in a radial way, mostly because the distance (circle) and direction (radius vector).

Can someone help me to get past my starting difficulties? Any help is gratefully appreciated!

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Answer 1

Image Analyst 2013-2-5

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I don't know what radial gradient is. Have you seen imgradient()? Or you can get the average gradient in all 8 directions just by convolving with [-1 -1 -1;-1 8 -1;-1 -1 -1].

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Christoph 2013-2-5

maybe that was a poor choice of words. All the objects I encounter in these images are circles or elliptical objects. So I need the gradient in form of 'going from the circle's center outwards'.

Thank you for your ideas, I will look into that immediately!

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