I want to reverse engineer a simple XY-line graph to scalar data values.
An example of such a plot is linked below, water temperature as a function of datetime. As far as I know, the raw data (sensor readings) and the processed numeric temperature values of this are not openly available on the internet, not in text format.
http://www.met.fu-berlin.de/de/daten/mevis-grafiken/TegelerSee/TEGSEE_Jahr_TT-WT.jpg
I think such tools are available as desktop applications (e.g. Neuralog) but those I know are nonfree, expensive, and require too much manual interaction.
What I want to do is process the same plot (linked above) again and again, say every two weeks. Automating the data cleanup (remove outliers, merge timeseries) seems doable to me.
(Maybe this been asked before by someone else on one of the other sites (software-recs, SO)...)