measuRing: An R package to measure tree-ring widths from scanned images

A new tool for the detection and measurement of tree-ring widths in wood was developed for the R environment. This tool, the measuRing package, integrates measurement of tree-ring widths with powerful statistical analyses within the R environment. The package assists in the identification of ring borders on scanned image sections from dendrochronological samples. It processes the image section and computes luminance data from images producing a matrix of gray values and a time series of smoothed gray values. Luminance data is plotted on segmented images for users to perform both visual identification of ring borders, or manual control of automatic detection. The package provides functions to visually include/exclude ring borders on the R graphical device, or automatically detect ring borders using a linear detection algorithm. This algorithm detects ring borders according to negative extreme values in the smoothed time-series of gray values. Users of the package can also implement other algorithms for automatic detection.