@Edward Cannon Hi Edward,
Thanks for the advice. Well, I am not getting any of the experimental data, any time soon. Since I am dealing with the sonic pressure values up to 600 kPa, I basically have one peak, and the rest is low amplitude noise about 0 kPa... [0,600] leaves me a lot of tolerance to work with. This is just for the specific cases I am dealing with now. Besides, I'm using this to evaluate the numerical studies vs the experimental data, so I am very happy with a coarse estimate, for now. Anyway, thanks a lot for the advice. Best regards, Tomislav > ----- Original Message ----- > From: Edward Cannon > Sent: 11/26/10 08:10 PM > To: tomislav_ma...@gmx.com > Subject: Re: [Image-SIG] experimental data diagram digitalization > > Your approach sounds pretty good, It will probably work. I might offer > this piece of advice: don't do it. Data looses precision as it is > graphed, and especially in the low resolutions used in many pdf > versions of articles. The descriptive statistics you compute are > likely to be incorrect. If you need the original data get it from a > publication or the paper author. If you intend to publish any results, > no journal will accept your recreated data. > Edward Cannon > Unicorn School > > On Fri, Nov 26, 2010 at 2:45 AM, tomislav_ma...@gmx.com > <tomislav.ma...@gmx.com> wrote: > > 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 > > _______________________________________________ > > Image-SIG maillist - image-...@python.org > > http://mail.python.org/mailman/listinfo/image-sig > > _______________________________________________ Image-SIG maillist - Image-SIG@python.org http://mail.python.org/mailman/listinfo/image-sig
