MATLAB Answers

how to find peaks in jpeg image

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guitoune mohieddine
guitoune mohieddine on 20 Jan 2015
Commented: Image Analyst on 28 Jan 2015
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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Answers (2)

Shoaibur Rahman
Shoaibur Rahman on 28 Jan 2015
You can try with Mablab's findpeaks function, or see the attached code in file exchange:

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Image Analyst
Image Analyst on 28 Jan 2015
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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Image Analyst
Image Analyst on 24 Jan 2015
Try this:
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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Image Analyst
Image Analyst on 27 Jan 2015
guitoune, do you have actual numerical data, or all you have is a printed image of a graph?
guitoune mohieddine
guitoune mohieddine on 28 Jan 2015
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
Image Analyst on 28 Jan 2015
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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