http://imagej.273.s1.nabble.com/Extract-Data-From-a-Plot-tp5017731p5017732.html
If I understand your problem correctly, you want a plot digitizer tool. I
> Hello,
> I need help extracting data from a plot. I found a very similar question
> in the ImageJ archives:
>
https://list.nih.gov/cgi-bin/wa.exe?A2=IMAGEJ;b522272.1502>
> However, the ImageJ plugin: Figure_Calibration requires the user to pick a
> few points from the ROI. My goal is to have ImageJ return a robust set of
> coordinates automatically.
> I am specifically interested in getting pump curve data from manufacturer’s
> published plots. The particular solution will allow users to:
>
> 1. Apply scaling to the ROI using Figure_Calibration.
> 2. Set the threshold to distinguish a particular pump curve from the
> background.
> 3. Use the wand tool to trace a particular curve.
> 4. Reduce the pixels that represent a curve to a set of data points
> following the median width of pixel distribution.
>
> As an example see the attached TIFF and Excel files, follow the 8” impeller
> curve. The data below was created using the Figure_Calibration plugin with
> 10 points selected with Multipoint tool. The particular pump curve looks
> very similar to the Figure_Calibration Tutorial here:
>
http://lukemiller.org/index.php/2011/09/digitizing-data-> from-old-figures-with-imagej/
>
> Ultimately, the new plugin would allow users to obtain a General Solution
> of the plot surface. The general plugin would allow users to “read” the
> domed surface plot from the efficiency contours, and create (or
> interpolate) slice segments through the efficiency dome for any possible
> pump curve (say 8.125 inches).
>
> Does this plugin already exist for ImageJ? I have seen references to two
> programs that supposedly do similar things:
>
http://markummitchell.github.io/engauge-digitizer/>
https://www.mathworks.com/matlabcentral/fileexchange/7173-grabit>
> I do not have administrative rights to use Engauge Digitizer, and I do not
> have a MATLAB license for GRABIT.
>
> Thank you for any help.
> Sincerely,
> -Matt Shaw
>
> Mechanical Engineer,
> U.S. Bureau of Reclamation
>
> Area Mean Min Max X Y
> 1 0 86 86 86 8.511 61.517
> 2 0 55 55 55 100 60.674
> 3 0 63 63 63 200 60.112
> 4 0 72 72 72 327.66 58.989
> 5 0 52 52 52 438.298 56.461
> 6 0 80 80 80 529.787 52.528
> 7 0 71 71 71 591.489 49.157
> 8 0 92 92 92 674.468 43.539
> 9 0 82 82 82 742.553 38.483
> 10 0 77 77 77 834.043 31.18
>
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