areaDetector Plugin NDPluginStats

Contents

• Overview
• Configuration
• Screen shots

Overview

NDPluginStats computes the following.

1. Basic statistics: minimum, maximum, mean, sigma, total, and net (background subtracted).
2. Centroid, sigma, skewness and kurtosis values in the X and Y dimensions.
3. Profiles of the array in the X and Y dimensions. A total of 8 profiles are calculated:
   • The average profiles in the X and Y directions.
   • The average profiles in the X and Y directions, for array elements greater than the centroid threshold.
   • The profiles in the X and Y directions at the X and Y centroid position.
   • The profiles in the X and Y directions at a user-defined X and Y cursor position.
4. A histogram of the values (e.g. number of pixels versus intensity per pixel).

Each calculcation can be independently enabled and disabled. Calculations 1 and 4 can be perfomed on arrays of any dimension. Calculations 2 and 3 are restricted to 2-D arrays.

Time-series arrays of the basic statistics, centroid and sigma statistics can also be collected. This is very useful for on-the-fly data acquisition, where the NDStats plugin computes the net or total counts in the detector or an ROI. It can also be used to quickly plot a time-history of beam position or width, etc. The time series can also be used in a circular buffer mode where is continuously displays the last N values of the statistic.

NDPluginStats inherits from NDPluginDriver. The NDPluginStats class documentation describes this class in detail.

NDPluginStats.h defines the following parameters. It also implements all of the standard plugin parameters from NDPluginDriver. The EPICS database NDStats.template provide access to these parameters, listed in the following table. Note that to reduce the width of this table the parameter index variable names have been split into 2 lines, but these are just a single name, for example NDPluginStatsComputeStatistics.

If the values of CentroidThreshold, CursorX, or CursorY are changed then the centroid and profile calculations are performed again immediately on the last array collected. Thus updated centroid statistics and profiles can be displayed even when new arrays are not being acquired. These calculations are only performed when enabled by ComputeCentroid and ComputeProfiles.

Configuration

The NDPluginStats plugin is created with the NDStatsConfigure command, either from C/C++ or from the EPICS IOC shell.

NDStatsConfigure(const char *portName, int queueSize, int blockingCallbacks,
               const char *NDArrayPort, int NDArrayAddr,
               int maxBuffers, size_t maxMemory,
               int priority, int stackSize)
  

For details on the meaning of the parameters to this function refer to the detailed documentation on the NDStatsConfigure function in the NDPluginStats.cpp documentation and in the documentation for the constructor for the NDPluginStats class.

Screen shots

The following MEDM screen provides access to the parameters in NDPluginDriver.h and NDPluginStats.h through records in NDPluginBase.template and NDStats.template.

NDStats.adl

The following MEDM screen shows the average profile of an image in the X direction.

NDPlot.adl

The following MEDM screen shows the profile of an image in the Y direction at the location of the user-defined cursor.

NDPlot.adl

The following MEDM screen shows the histogram of intensities of an array.

NDPlotXY.adl

The following MEDM screen combines many parameters for 5 NDPluginStats plugins on a single screen.

NDStats5.adl

The following MEDM screen shows the the total counts from the Stats1 plugin. This is the total counts as a function of time.

NDTimeSeries.adl

The following MEDM screen shows the Y centroid as a function of time from the Stats1 plugin.

NDTimeSeries.adl

The following MEDM screen shows all of the basic statistics as a function of time from the Stats1 plugin.

NDStatsTimeSeriesBasicAll.adl

The following MEDM screen shows all of the centroid statistics as a function of time from the Stats1 plugin.

NDStatsTimeSeriesCentroidAll.adl