RGB: Layers representing colors

In rspatial/terra: Spatial Data Analysis

Layers representing colors

Description

With RGB you can get or set the layers to be used as Red, Green and Blue when plotting a SpatRaster. Currently, a benefit of this is that plot will send the object to plotRGB. You can also associated the layers with another color space (HSV, HSI or HSL)

With colorize you can convert a three-layer RGB SpatRaster into other color spaces. You can also convert it into a single-layer SpatRaster with a color-table.

Usage

## S4 method for signature 'SpatRaster'
RGB(x)

## S4 replacement method for signature 'SpatRaster'
RGB(x, ..., type="rgb")<-value

## S4 method for signature 'SpatRaster'
colorize(x, to="hsv", alpha=FALSE, stretch=NULL, 
	grays=FALSE, NAzero=FALSE, filename="", overwrite=FALSE, ...)

## S4 method for signature 'SpatRaster'
has.RGB(x, strict=TRUE)

Arguments

x	SpatRaster
value	vector of three (or four) positive integers indicating the layers that are red, green and blue (and optionally a fourth transparency layer). Or NULL to remove the RGB settings
type	character. The color space. One of "rgb" "hsv", "hsi" and "hsl"
to	character. The color space to transform the values to. If x has RGB set, you can transform these to "hsv", "hsi" and "hsl", or use "col" to create a single layer with a color table. You can also use "rgb" to back transform to RGB
alpha	logical. Should an alpha (transparency) channel be included? Only used if x has a color-table and to="rgb"
stretch	character. Option to stretch the values to increase contrast: "lin" (linear) or "hist" (histogram). Only used for transforming RGB to col
grays	logical. If TRUE, a gray-scale color-table is created. Only used for transforming RGB to col
NAzero	logical. If TRUE, NAs are treated as zeros such that a color can be returned if at least one of the three channels has a value. Only used for transforming RGB to ("col")
strict	logical. If TRUE, the function returns FALSE if a color space such as "hsv", "hsi" and "hsl" is used
filename	character. Output filename
overwrite	logical. If TRUE, filename is overwritten
...	additional arguments for writing files as in writeRaster

Examples

r <- rast(system.file("ex/logo.tif", package="terra"))   
plot(r)
has.RGB(r)
RGB(r) <- NULL
has.RGB(r)
plot(r)
RGB(r) <- c(3,1,2)
plot(r)

RGB(r) <- 1:3
x <- colorize(r, "col")
y <- colorize(r, "hsv")
z <- colorize(y, "rgb")

rspatial/terra documentation built on Nov. 5, 2024, 5:13 p.m.