samples, and p2 is the 90th percentile
  value.
  
  ZOOM specifies the number of matrix samples per screen pixel.  It
  will be rounded to an integer, or 1 divided by an integer.  A value
  of 'same' or 'auto' (default) causes the zoom value to be chosen
  automatically to fit the image into the current axes.  A value of
  'full' fills the axis region (leaving no room for labels).  See
  pixelAxes.m.
  
  If LABEL (optional, default = 1, unless zoom='full') is non-zero, the range 
  of values that are mapp