How to correct background to extract fine features of a signal containing multiple gaussian envelopes?

Question

ct8 2023-3-3

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https://ww2.mathworks.cn/matlabcentral/answers/1922830-how-to-correct-background-to-extract-fine-features-of-a-signal-containing-multiple-gaussian-envelope

评论： ct8 2023-3-3

test.mat

I am trying to extract fine features and plot them from a signal that consists of two distinct gaussian envelopes. I used the background correction code below https://www.mathworks.com/matlabcentral/fileexchange/27429-background-correction

Apparently, the code works only for signals with one gaussian envelope (I may be wrong?); but i could not get the desired result. I cannot simply apply gaussian filtering because it will modify the linewidths of the fine features, which are of key importance in this singal.

Any help to resolve this issue would be highly appreciated. I have attached a .mat file to give folks an idea about how the vectors look like.

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Answer 1

Image Analyst 2023-3-3

在 MATLAB Online 中打开

What is this? What generated the signal? It already looks like a baseline-corrected signal. I'm not sure you'd want to do anything to that signal.

s = load('ct8.mat')

s = struct with fields:

x1: [1340×1 double] y1: [1340×1 double]

x = s.x1;

y = s.y1;

plot(x, y, 'b-');

grid on;

figure;

s = load('ct8.mat');

x = s.x1;

y = s.y1;

subplot(2, 1, 1);

plot(x, y, 'b-');

grid on;

smoothy = sgolayfilt(y, 2, 151);

hold on;

plot(x, smoothy, 'r-', 'LineWidth', 2)

subplot(2, 1, 2);

yDiff = y - smoothy;

plot(x, yDiff, 'b-');

grid on;

If you were to subtract out the baseline, where would you put it? Can you attach a picture of the baseline drawn in red underneath the signal? By the way, I'm attaching some demos for you to adapt.

Or maybe you could use sgolayfilt to get a smoothed version of the signal and then subtract it.