2D Autocovariance or Autocorrelation Function

DESCRIPTION:

Estimates and displays 2D autocovariance or autocorrelation function for an image.

USAGE:

acf.2d(x, lag.max=NULL, type="correlation", plot=T, ...) 

REQUIRED ARGUMENTS:

x
an image or a matrix.

OPTIONAL ARGUMENTS:

lag.max
integer vector of length two; the maximum number of lags at which to estimate the autocorrelation. If it is not supplied, it is an integer proportional to the logarithm of the row length, or a vector of two integers proportional to the logarithms of the row and column lengths.
type
a character string: "covariance" to estimate the autocovariance function; "correlation" for the autocorrelation function.
plot
logical flag, if TRUE, the 2D autocorrelation function will be plotted.
...
additional arguments for image.

VALUE:

a matrix of size lag.max.

DETAILS:

The autocorrelations are computed by using fft.

SEE ALSO:

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