[Image-SIG] experimental data diagram digitalization

Andrew Hawryluk HAWRYLA at novachem.com
Tue Nov 30 23:51:56 CET 2010

Unless you need to batch-process dozens of diagrams, you will probably be better off using an existing utility. While it's not as good as getting original data, it's better than guessing all of the numbers by eye.


Good luck!

> -----Original Message-----
> From: image-sig-bounces+hawryla=novachem.com at python.org [mailto:image-
> sig-bounces+hawryla=novachem.com at python.org] On Behalf Of
> tomislav_maric at gmx.com
> Sent: Friday, November 26, 2010 3:45 AM
> To: image-sig at python.org
> Subject: [Image-SIG] experimental data diagram digitalization
> Hi everyone,
> I need to digitalize a diagram of experimental data. I have been
> reading the documentation of the Python Imaging Library, and I'm
> thinking that I can approach my problem in the following way:
> 1) Create a .png of the diagram I find in the literature (.pdf
> articles, or theses).
> 2) Clean up the diagram (remove the axes, the text and leave only the
> data that I am interested in).
> 3) Read the image.
> 4) Apply a filter that will result in only those pixels that are non-
> white (pick up the experimental data).
> 5) Scale the result data of the filter (in pixels) to the actual
> coordinates in the image in milimeters.
> 6) Scale the milimeter coordinates to the actual scale of the diagram
> (read from the original .pdf), to get the
>    true coordinates (in my case, I have time in seconds and pressure in
> kPa).
> Can this be done with the Python Imaging Library + some additional
> python coding?
> The other option would be to use inkscape to export the path into .svg
> and manipulate (scale) it with some python-XML library.
> Can anyone give me some advice on this issue?
> Thanks in advance,
> Tomislav
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