Rotate 16x16 Matrix

I'm trying to figure out how to rotate a 16x16 matrix 90 degrees (clockwise and counter-clockwise) by pressing buttons.
I'm using jit.rota, but it doesnt work because the anchor point is
set at a pixel (x-8/y-8). And the middle of my matrix falls between the pixels.

Is there another way to do rotations?

Thanks for your help.