At the 2012 MMS meeting at UNH, a group of us proposed that we embed a little metadata within PNG images which provides lookup information in JSON format. Here is an example:
See http://autoplot.org/richPng{ "size":[722,639], "numberOfPlots":1, "plots": [ { "title":"AC/MFI [PRELIMINARY VALUES - BROWSE USE ONLY] B-field magnitude", "xaxis": { "label":"", "min":"2014-01-02T00:00:00.000Z", "max":"2014-01-03T00:00:00.000Z", "left":78, "right":644, "type":"lin", "units":"UTC" }, "yaxis": { "label":"[PRELIM] <|B|> (nT)", "min":4.440892098500626E-16, "max":8.9, "top":52, "bottom":587, "type":"lin", "units":"nT" } } ] }
return the range setting of the axis. This looks at the "min" and "max" keys of the axis node.
attempt to get the time range of the plots, looking at each x axis for a timerange.