imager (version 0.42.19)

imsub: Select part of an image

Description

imsub selects an image part based on coordinates: it allows you to select a subset of rows, columns, frames etc. Refer to the examples to see how it works

Usage

imsub(im, ...)
subim(im, ...)

Value

an image with some parts cut out

Arguments

im

an image

...

various conditions defining a rectangular image region

Functions

• subim(): alias for imsub

Author

Simon Barthelme

Details

subim is an alias defined for backward-compatibility.

Examples

parrots <- load.example("parrots")
imsub(parrots,x < 30) #Only the first 30 columns
imsub(parrots,y < 30) #Only the first 30 rows
imsub(parrots,x < 30,y < 30) #First 30 columns and rows
imsub(parrots, sqrt(x) > 8) #Can use arbitrary expressions
imsub(parrots,x > height/2,y > width/2)  #height and width are defined based on the image
#Using the %inr% operator, which is like %in% but for a numerical range
all.equal(imsub(parrots,x %inr% c(1,10)),
  imsub(parrots,x >= 1,x <= 10))
imsub(parrots,cc==1) #Colour axis is "cc" not "c" here because "c" is an important R function
##Not run
##imsub(parrots,x+y==1)
##can't have expressions involving interactions between variables (domain might not be square)