as.cimg.function: Create an image by sampling a function

In imager: Image Processing Library Based on 'CImg'

Create an image by sampling a function

Description

Similar to as.im.function from the spatstat package, but simpler. Creates a grid of pixel coordinates x=1:width,y=1:height and (optional) z=1:depth, and evaluates the input function at these values.

Usage

## S3 method for class ''function''
as.cimg(
  obj,
  width,
  height,
  depth = 1,
  spectrum = 1,
  standardise = FALSE,
  dim = NULL,
  ...
)

Arguments

obj	a function with arguments (x,y), or (x,y,cc), or (x,y,z), etc. Must be vectorised; see examples.
width	width of the image (in pixels)
height	height of the image (in pixels)
depth	depth of the image (in pixels). Default 1.
spectrum	number of colour channels. Defaut 1.
standardise	coordinates are scaled and centered (see doc for pixel.grid)
dim	a vector of image dimensions (can be used instead of width, height, etc.)
...	ignored

Value

an object of class cimg

Author(s)

Simon Barthelme

Examples

im = as.cimg(function(x,y) cos(sin(x*y/100)),100,100)
plot(im)
#The following is just a rectangle at the center of the image 
im = as.cimg(function(x,y) (abs(x) < .1)*(abs(y) < .1) ,100,100,standardise=TRUE)
plot(im)
#Since coordinates are standardised the rectangle scales with the size of the image
im = as.cimg(function(x,y) (abs(x) < .1)*(abs(y) < .1) ,200,200,standardise=TRUE)
plot(im)
#A Gaussian mask around the center
im = as.cimg(function(x,y) dnorm(x,sd=.1)*dnorm(y,sd=.3) ,dim=dim(boats),standardise=TRUE)
im = im/max(im)

plot(im*boats)
#A Gaussian mask for just the red channel
fun = function(x,y,cc) ifelse(cc==1,dnorm(x,sd=.1)*dnorm(y,sd=.3),0)
im = as.cimg(fun,dim=dim(boats),standardise=TRUE)
plot(im*boats)

imager documentation built on May 29, 2024, 1:38 a.m.