Variance for Image objects

S3 generic extending var to support Image objects. Non-Image inputs delegate to stats::var.

Usage

var(x, ...)

# Default S3 method
var(x, y = NULL, na.rm = FALSE, use, ...)

# S3 method for class 'Image'
var(x, ...)

x: An Image object, or a numeric vector/matrix for the default method.
...: Additional arguments passed to methods.
y: NULL or a numeric vector/matrix; passed to stats::var for non-Image objects.
na.rm: Logical; should missing values be removed? Passed to stats::var for non-Image objects (ignored for Image).
use: An optional character string specifying the method for computing covariances; passed to stats::var for non-Image objects.

For Image inputs, a numeric vector of per-channel variances. For other inputs, the result of var.