R: Find Location of Maximum in a Pixel Image

where.max {spatstat.geom} | R Documentation

## Find Location of Maximum in a Pixel Image

### Description

Finds the spatial location(s) where a given pixel image attains its maximum or minimum value.

### Usage

      where.max(x, first = TRUE)
      where.min(x, first = TRUE)

### Arguments

`x` | A pixel image (object of class `"im"`) or data that can be converted to a pixel image by `as.im`.
`first` | Logical value. If `TRUE` (the default), then only one location will be returned. If `FALSE`, then all locations where the maximum is achieved will be returned.

### Details

This function finds the spatial location or locations where the pixel image `x` attains its maximum or minimum value. The result is a point pattern giving the locations.

If `first=TRUE` (the default), then only one location will be returned, namely the location with the smallest y coordinate value which attains the maximum or minimum. This behaviour is analogous to the functions `which.min` and `which.max`.

If `first=FALSE`, then the function returns the locations of all pixels where the maximum (or minimum) value is attained. This could be a large number of points.

### Value

A point pattern (object of class `"ppp"`).

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

### See Also

`Summary.im` for computing the minimum and maximum of pixel values; `eval.im` and `Math.im` for mathematical expressions involving images; `solutionset` for finding the set of pixels where a statement is true.

### Examples

       D <- distmap(letterR, invert=TRUE)
       plot(D)
       plot(where.max(D), add=TRUE, pch=16, cols="green")

[Package spatstat.geom version 2.3-2 Index]