Look-up Table Transform

LUT performs a look-up table transform of an Image object.

Usage

LUT(image, lut, target = "new")

Arguments

image

An 8-bit (8U) Image object.

lut

A look-up table. This should be a vector with 256 elements, or a 256 x n matrix, with n corresponding to the number of channels in image. If lut is a vector and image has more than one channel, then lut is recycled for each channel.

target

The location where the results should be stored. It can take 3 values:

"new":

a new Image object is created and the results are stored inside (the default).

"self":

the results are stored back into image (faster but destructive).

An Image object:

the results are stored in another existing Image object. This is fast and will not replace the content of image but will replace that of target. Note that if target does not have the same dimensions, number of channels, and bit depth as image, nothing will be stored.

Value

If target="new", the function returns an Image object. If target="self", the function returns nothing and modifies image in place. If target is an Image object, the function returns nothing and modifies that Image object in place.

See also

Image, histmatch

Author

Simon Garnier, garnier@njit.edu

Examples

balloon <- image(system.file("sample_img/balloon1.png", package = "Rvision"))
high_contrast_lut <- 255 * pbeta(0:255 / 255, 4, 4)
high_contrast_balloon <- LUT(balloon, high_contrast_lut)