I would like to plot an image without showing *anything* in the figure
except the image itself.  That means that I would like to remove the x
and y axis entirely.  I can remove the right y-axis and the top x-axis
by
set(gca, 'box', 'off') ;
But that leaves the left y-axis and bottom x-axis in place.  I can
then remove ticks and labels by
set(gca, 'xtick', [], 'ytick', []) ;
But the x and y axis lines are still visible.  I can set the axes to
the background color,
set(gca, 'xcolor', 'w', 'ycolor', 'w') ;
But sometimes the axes re-appear when I copy & paste the figure, or
when I print it.
How do I remove these stubborn axes for good, or make them entirely
invisible?

Just realized the following solution will hide all axis lines.  Sorry
for missing this.
set(gca, 'visible', 'off') ;