| iTool User's Guide: Working with Plots |

## Filtering a Plot

The iPlot tool allows you to modify your plot data in the following ways:

### Plot Smoothing

Within the iPlot tool, plots can also be smoothed to soften edges or compensate for random noise in the plot. To smooth your plot from the iPlot window, select Operations Filter Smooth.

Figure 13-12: Damped Sine Plotted Data (left) and Smoothed Data (right)

Figure 13-12: Damped Sine Plotted Data (left) and Smoothed Data (right)

Note The example shown in the previous figures is taken from example data available in the`examples\data` directory of your IDL installation. The data is contained in a file called `damp_sn.dat`.

Note The window's default size is three, however this can be changed via the operations browser. For more information on smoothing properties, see Smooth Properties.

### Plot Convolution

You can also use the iPlot convolution feature by selecting Operations Filter Convolution. By selecting this, the Convolution Editor appears. From this dialog, you can select the desired convolution type from a drop-down list or you can manually manipulate the columns, rows, scale factor, and details.

For more information on convolution properties, see Convolution Properties.

### Plot Median

The median filter replaces each point with the median (a value in an ordered set of values with an equal number of values above and below it) of the one- or two-dimensional neighborhood of a given width.

To apply the smooth filter to an image:

1. Select the plot.

2. Select Operations Filter Median.

For more details on the median filter, see Median Filter.

IDL Online Help (March 01, 2006)