       Re: Digitizing plots with Mathematica (i.e. extracting data points

• To: mathgroup at smc.vnet.net
• Subject: [mg107685] Re: Digitizing plots with Mathematica (i.e. extracting data points
• From: "Kevin J. McCann" <Kevin.McCann at umbc.edu>
• Date: Mon, 22 Feb 2010 19:05:25 -0500 (EST)
• References: <hlte0v\$s7c\$1@smc.vnet.net>

```You should probably also consider the possibility that your image is not
exactly horizontal/vertical. This will likely be the case if you scan an
image from a book or journal.

Kcvin

Will DeBeest wrote:
> I've just written a blog post showing how to make a plot digitizer
> using Mathematica. It may be of interest to other Mathematica users
> particularly anyone who wants to extract some data out of plots.
>
> barChartDigitizer[g_Image] :=
>  DynamicModule[{min = {0, 0}, max = {0, 0}, xmin = -1., xmax = 1.,
>    pt = {0, 0}, data = {}, img = ImageDimensions[g], output},
>
>   Deploy@Column[{
>      Row[{
>        Column[{Button["Y Axis Min", min = pt],
>          InputField[Dynamic[xmin], Number, ImageSize -> 70]}],
>        Column[{Button["Y Axis Max", max = pt],
>          InputField[Dynamic[xmax], Number, ImageSize -> 70]}],
>          Button["Remove Last", data = Quiet@Check[Most@data, {}]]}],
>        Column[{Button["Start Over", data = {}],
>          Button["Print Output",
>           Print@Column[{BarChart[
>               output =
>                Rescale[#, {Last@min, Last@max}, {xmin, xmax}] & /@
>                 data[[All, 2]],
>               PlotRange -> {Automatic, {xmin, xmax}},
>               ImageSize -> 400], output}],
>           Enabled -> Dynamic[data =!= {}]]}]
>        }],
>      Row[{
>        Graphics[{Inset[
>           Image[g, ImageSize -> img]], {Tooltip[Locator[Dynamic[pt]],
>            Dynamic[pt]]}},
>         ImageSize -> img, PlotRange -> 1,
>         AspectRatio -> img[]/img[]]}]
>      }]
>   ]
>
> A full description will a worked example can be found here:
>
> http://www.wildebeests.net/2010/02/21/digitizing-plots-with-mathematica/
>

```

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