Read and plot a tree-ring image file

This function can read an image file from the hard disk and plot it in a newly-opened graphics device.

Usage

ring_read(img, dpi = NULL, RGB = c(0.299, 0.587, 0.114),
  plot = FALSE, rotate = 0, magick = TRUE)

Arguments

img

A character string indicating the path of the image file. Supported formats include png, tiff, jpg and bmp.

dpi

An integer specifying the dpi of the image file. A minimum of 300 dpi is required when running automatic detection.

RGB

A numeric vector of length 3 giving the weight of RGB channels.

plot

A logical value indicating whether to plot the tree ring image when reading it. If FALSE, the image is not plotted until function ring_detect or pith_measure is called.

rotate

An integer specifying how many degrees to rotate (clockwise). It requires one of the following values: 0, 90, 180 or 270.

magick

A logical value. If TRUE, magick is used to read the tree ring image. If FALSE, packages png, jpg and tiff are used instead. See details below.

Value

A magick image object containing the image data.

Details

Proper image preparation has a great influence on the measurement of ring widths. A tree-ring image should not contain irrelevant or redundant features, such as wooden mounts where cores are glued. The larger the file size of an image, the slower the image processing operation will be.

Pith side of a wood sample should be placed on the right side of a graphics window. Use rotate to change its position.

It is highly recommended to use the default value magick = TRUE, because magick can significantly reduce the memory usage when reading a large file. If image data is stored in a non-standard format, image reading may fail. In that case you can set magick = FALSE to avoid the use of magick.

Author

Jingning Shi

Examples

img.path <- system.file("001.png", package = "MtreeRing")

## Read and plot the image:
t1 <- ring_read(img = img.path, dpi = 1200, plot = TRUE)