Is 'splot ... with rgbimage' supposed to work?

[Ethan A M. <merritt@u.washington.edu>]

The docs say:

  The `rgbimage` style is intended for plotting 2D images and is
  similar in concept to `image`.  See `image` for details.
  The difference is that 5D data (x,y,r,g,b) for `plot` and 
  6D data (x,y,z,r,g,b) for `splot` describe the coordinates
  and color components of an image.

However, I cannot find such an splot command that works in either
gnuplot 4.2-rc1 or cvs.

  gnuplot> # This works. It is from image.dem. But it reads only one of the 3 color channels.
  gnuplot> splot 'blutux.rgb' binary array=128x128 flip=y format='%uchar' using 1:2:3 with image   

  gnuplot> splot 'blutux.rgb' binary array=128x128 flip=y format='%uchar' using 1:2:(0):3:4:5 with rgbimage
           Too many columns in using specification and implied sampling array

  gnuplot> splot 'blutux.rgb' binary array=128x128x1 flip=y format='%uchar' using 1:2:3 with rgbimage
           Currently do not support sampled array dimensions greater than 2

So how am I supposed to specify these 6 columns of data for a 3D rgbimage plot?

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742