writeTIFF.RdWrites images into a TIFF file or a raw vector representing such.
writeTIFF(what, where, bits.per.sample = 8L,
compression = c("LZW", "none", "PackBits", "RLE", "JPEG", "deflate"),
reduce = TRUE)either an image or a list of images. An image is a real matrix
or array of three dimensions, or an object of the class "nativeRaster".
file name or a raw vector
number of bits per sample (numeric scalar). Supported values in this version are 8, 16, and 32.
desired compression algorithm (string). Optionally, it can be specified as a numeric value corresponding to the compression TIFF tag, but it needs to be also supported by the underlying TIFF library
if TRUE then writeTIFF will attempt to
reduce the number of planes in native rasters by analyzing the
image to choose one of RGBA, RGB, GA or G formats, whichever uses
the least planes without any loss. Otherwise the image is always
saved with four planes (RGBA).
If where is a raw vector then the value is the raw vector
containg the TIFF contents, otherwise a scalar integer specifying the
number of images written in the file.
By default writeTIFF uses the same number of planes as
there are planes in the input image. For native images it is always
four unless reduce = TRUE is set (see above). Consequently,
color maps are not used. The output always uses contiguous planar
configuration (baseline TIFF). The output is tagged with a photometric
tag of either RGB (3 or 4 planes) or zero-is-black (1 or 2 planes). If
what is a list then the TIFF output will be a directory of the
corresponding number of images (in TIFF speak - not to be confused
with file directories).
img <- readTIFF(system.file("img", "Rlogo.tiff", package="tiff"))
# write without the alpha channel
tiff <- writeTIFF(img[,,-4], raw(0))
# read as native
i2 <- readTIFF(tiff, native=TRUE)
# write reduced - should be the same as tiff
t2 <- writeTIFF(i2, raw(0), reduce=TRUE)