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plotting - How can I extract trace points from an oscilloscope image?


I have the following oscilloscope image:


enter image description here


I would like to extract the points of the yellow curve together with the correct values. Do you know how I could do it?


Extracting the yellow curve from the background seems quite difficult to me.



Answer



Here I trim manually, but you could use Image[MorphologicalComponents[img] and detect the bounding box instead (actually, that's how I found 57 and 455).



img = Import["https://i.stack.imgur.com/NYfVj.png"]
pt1 = {12, 57};
pt2 = {600, 455};
imgCurve = ImageTrim[Image[MorphologicalComponents[img2]], {pt1, pt2}]
imgGrid = ImageTrim[Image[MorphologicalComponents[img]], {pt1, pt2}] - imgCurve

enter image description here


enter image description here


Then it's not difficult to get the points:


data1 = ImageData[Binarize@imgCurve];

points = Reverse /@ Position[data1, 1];
points[[All, 2]] = 520 - points[[All, 2]];
ListPlot@points

enter image description here


If you understand this, then you can extract the width and height of the grid, and scale the points accordingly.


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