bytscl(z, top= max_byte, cmin= lower_cutoff, cmax= upper_cutoff) split_bytscl (x, upper, cmin = None, cmax = None)
"b") of the same shape as Z, with values
linearly scaled to the range 0 to one less than the current palette size. If MAX_BYTE is specified, then
the scaled values will run from 0 to MAX_BYTE instead. If LOWER_CUTOFF and/ or UPPER_CUTOFF
are specified, Z values outside this range are mapped to the cutoff value; otherwise the linear scaling
maps the extreme values of Z to 0 and MAX_BYTE.
split_bytscl is as the bytscl function, but scales to the lower half of a split palette (0-99,
normally the color scale) if the second parameter is zero or nil, or the upper half (100-199, normally
the gray scale) if the second parameter is non-zero.