rgdal (version 1.5-32)

RGB2PCT: Convert RGB three band to single band colour table

Description

This function converts a three-band GDALReadOnlyDataset into a single band of colour indices as a GDALTransientDataset.

Usage

RGB2PCT(x, band, driver.name = 'MEM', ncolors = 256, set.ctab = TRUE)

Value

The value returned is a either GDALTransientDataset or a list of a GDALTransientDataset and a colour table.

Arguments

x

a three-band GDALReadOnlyDataset object

band

a vector of numbers, recycled up to 3 in length

driver.name

default MEM

ncolors

a number of colours between 2 and 256

set.ctab

default TRUE, when the dithered dataset handle is returned, otherwise a list of the dataset and the PCT colour table

Author

Tim Keitt

References

https://gdal.org/

Examples

if (FALSE) {
logo <- system.file("pictures/Rlogo.jpg", package="rgdal")[1]
x <- GDAL.open(logo)
dim(x)
dx <- RGB2PCT(x, band=1:3)
displayDataset(dx, reset.par=FALSE)
dim(dx)
GDAL.close(x)
GDAL.close(dx)
}