R: Mean and Median of Pixel Values in an Image

mean.im {spatstat.geom} | R Documentation

## Mean and Median of Pixel Values in an Image

### Description

Calculates the mean or median of the pixel values in a pixel image.

### Usage

    ## S3 method for class 'im'
    ## mean(x, trim=0, na.rm=TRUE, ...)

    ## S3 method for class 'im'
    ## median(x, na.rm=TRUE)        [R < 3.4.0]
    ## median(x, na.rm=TRUE, ...)   [R >= 3.4.0]

### Arguments

`x` | A pixel image (object of class `"im"`).
`na.rm` | Logical value indicating whether `NA` values should be stripped before the computation proceeds.
`trim` | The fraction (0 to 0.5) of pixel values to be trimmed from each end of their range, before the mean is computed.
`...` | Ignored.

### Details

These functions calculate the mean and median of the pixel values in the image `x`.

An object of class `"im"` describes a pixel image. See `im.object`) for details of this class.

The function `mean.im` is a method for the generic function `mean` for the class `"im"`. Similarly `median.im` is a method for the generic `median`.

If the image `x` is logical-valued, the mean value of `x` is the fraction of pixels that have the value `TRUE`. The median is not defined.

If the image `x` is factor-valued, then the mean of `x` is the mean of the integer codes of the pixel values. The median is are not defined.

Other mathematical operations on images are supported by `Math.im`, `Summary.im` and `Complex.im`.

Other information about an image can be obtained using `summary.im` or `quantile.im`.

### Value

A single number.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk and Kassel Hingee.

### See Also

`Math.im` for other operations.

Generics and default methods: `mean`, `median`.

`quantile.im`, `anyNA.im`, `im.object`, `summary.im`.

### Examples

      X <- as.im(function(x,y) {x^2}, unit.square())
      mean(X)
      median(X)
      mean(X, trim=0.05)

[Package spatstat.geom version 2.2-0 Index]