| pack8bit(wavethresh) | R Documentation |
In image processing, often pictures are stored as long array of values
in 0:255. For (file) storage, these can be packed into 32 bit
integers. These functions are for packing and unpacking.
pack8bit(v8) unpack8bit(v)
v8 |
integer vector with 8-bit elements in 0..255. |
v |
integer vector (at least 32 bits). |
If the length of v8 is not a multiple of 4, v8
is effectively padded with one to three 0s.
The implementation is straightforward and short; look at the function definitions.
pack8bit(v8) returns an integer vector of length
ceiling(length(v8) / 4).
unpack8bit(v) returns a vector of values from 0:255 of
length 4 * length(v).
Martin Maechler
compress etc for wavelet compression.
pack8bit(0:11) all(pack8bit(0:11) == pack8bit(0:9)) all(0:255 == unpack8bit(pack8bit(0:255)))