Packs information from each element of two vectors into the result vector.
Elemental function
The result is a pixel vector.
The value of each element of the result vector is taken from the corresponding element of the result of concatenating ARG1 and ARG2 in the following way: the least significant bit of the high order byte is stored into the first bit of the result element; the least significant 5 bits of each of the remaining bytes are stored into the remaining portion of the result element.