imsub {imager}

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, ...)

Arguments

im

an image

...

various conditions defining a rectangular image region

Details

subim is an alias defined for backward-compatibility.

Value

an image with some parts cut out

Functions

• subim(): alias for imsub

Author(s)

Simon Barthelme

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)