how to find the change in curve

Question

prashant singh 2017-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/358253-how-to-find-the-change-in-curve

回答： Image Analyst 2017-9-25

i have plotted a curve on my image. The curve is shown in red. I want to find the jump in my curve with some good algroithm. The area in the curve where i want to detect jump is shown in blue. I have tried to find difference between two point to detect jump but that always does not return me the points in the curve i want(show in blue).

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Cedric 2017-9-25

But you have the red curve as e.g. a row vector already? If so, could you attach it?

prashant singh 2017-9-25

ridx.mat

Attaching row vector for the curve.

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Answer 1

Image Analyst 2017-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/358253-how-to-find-the-change-in-curve#answer_283070

Have you tried findchangepts()?

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Answer 2

Star Strider 2017-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/358253-how-to-find-the-change-in-curve#answer_283062

在 MATLAB Online 中打开

Try this:

D = load('ridx.mat');
ridx = D.ridx;
ridx = max(ridx)-ridx;
x = 1:length(ridx);
dt_ridx = detrend(ridx);
mask = dt_ridx > 27;
figure(1)
plot(x, ridx)
hold on
plot(x(mask), ridx(mask), '-r', 'LineWidth',1.2)
hold off
grid