Extract the X and Y values of curve in image

Question

Habib 2020-1-16

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https://ww2.mathworks.cn/matlabcentral/answers/500608-extract-the-x-and-y-values-of-curve-in-image

评论： Image Analyst 2020-3-27

Hi every one.

I have an image like this

I want to extract X and Y curve values. Unfortunately it's .fig file was lost. I have to have its y values. I have tried codes like Nassim Grabbit, ... but they were not more helpful.

Please suggest other ways to solve my problem

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JohnE 2020-3-26

If anyone is interested, we have launched a free graph digitizer. You can use it to extract 1000's of points on a spectral curve in seconds. Give it a try and let me know what you think.

https://www.opticsforhire.com/graph-digitizer

John

Image Analyst 2020-3-27

Why not put it in the MATLAB Central File Exchange?

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Answer 1

Adam Danz 2020-1-17

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Without the original data or the figure file you'll have to use a digitizing program that estimates the coordinates of the curve based on the image.

You can start with Jiro's grabit(). You mentioned that you tried this but had problems. It may require some pre-processing, cleaning up the image before processing, or eliminating any objects in the image that are interfering with the extraction. That all could be done from a 3rd party image editing program.

If that doesn't work for you, perhaps there are other programs on the file exchange you could try. Here's are some suggestions.

Outside of Matlab there is GetData, Engauge Digitizer, and probably others I'm not aware of.

Depending on what the data look like in your image, you may have to edit the image before processing and you may have to play around with the options offered in each of these programs. It may not be as simple as plug-and-chug.