bitmap - Approximate Area with Grid-Aligned Rectangles -

so have complicated shape want approximate union of n grid-aligned (x/y axis) rectangles, we'll call b.

for simplicity let's rendered bitmap. means rectangle corners on lattice points.

the metric wanted use , minimize area of xor b, use another.

i'm guessing np, , purposes fast approximation suffice. generated rectangle set should within amount of optimal solution.