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Extracting x,y data from scanned images of plotted data

• To: mathgroup at smc.vnet.net
• Subject: [mg124575] Extracting x,y data from scanned images of plotted data
• From: gac <g.crlsn at gmail.com>
• Date: Wed, 25 Jan 2012 07:05:16 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

I have a scanned image (JPG, black and white) of a plot of experimental data.  Unfortunately for me, the original numerical data values are not available.

The data is depicted as ~20 nested curves somewhat parabolic in shape (concave down).  Each curve is open, but continuous from end to end.  The curves do not intersect, and there are no data markers. 

I thought of using the image processing capabilities of Mathematica 8 to extract approximate values of the plotted data for use in further calculations.  

IOW, I want to use Mathematica to determine a set of x,y pairs for each curve.  I could then use Mathematica to determine an InterpolationFunction for the plotted data.  I could easily provide the proper scale after Mathematica determines the x,y pairs.

Any advice?

Thanks very much.

gac