imshow feature?

The checkerboard goes to the edges but the color overlay

    > has a gap on the right and bottom. I have not been able to
    > figure this out.

Nor have I completely, yet. It's related to interpolation (worse for
bilinear and bicubic that nearest). matlab handles this (at least for
pcolor) by setting the axes lim to not include the last row. Eg, for
a 5x5 pcolor grid, the axes would be 4x4.

This is part of the problem, but there may be an off-by-one or
rounding error as well.

It's a priority to fix, only it ain't fixed yet!