how to find peaks in jpeg image

Question

guitoune mohieddine 2015-1-20

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https://ww2.mathworks.cn/matlabcentral/answers/170689-how-to-find-peaks-in-jpeg-image

评论： Image Analyst 2015-1-28

hi i am new in matlab, and i want to extract peaks from a spectrum peg image and store the peak in vector

this is a spectrum image jpeg file ,so how i can extract peaks from it

please help me .

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Answer 1

Shoaibur Rahman 2015-1-28

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https://ww2.mathworks.cn/matlabcentral/answers/170689-how-to-find-peaks-in-jpeg-image#answer_166289

You can try with Mablab's findpeaks function, or see the attached code in file exchange:

http://www.mathworks.com/matlabcentral/fileexchange/48818-peak-detection-of-a-function

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Image Analyst 2015-1-28

Won't work, at least not right away. He said he does not have the data but has an image that is a scan of a printout. First, from that image, he needs to get the 1-D signal data, then he can use findpeaks().

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Answer 2

Image Analyst 2015-1-24

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https://ww2.mathworks.cn/matlabcentral/answers/170689-how-to-find-peaks-in-jpeg-image#answer_165790

Try this:

http://www.mathworks.com/matlabcentral/fileexchange/36904-matlab-script-for-digitizing-a-published-graph

But you'll have to decide how many elements you want the signal divided up into, say 500 or 1000 elements. And once you do that you can't get any wavenumbers because all we know is that the first element is around 2180. We have no idea what the last element in the array would have for a wavenumber because it's not shown on the plot.

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guitoune mohieddine 2015-1-28

I have a printed image jpeg like this , so code matlab get the peaks and valleys automatically, i thik you enderstand me , please help me .

image

Image Analyst 2015-1-28

编辑：Image Analyst 2015-1-28

Do we need to assume that the axes can be tilted, or can we assume that they are aligned with the image rows and columns? What about the color of the plotted line? Black, blue, or any possible color, except pure white?

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