#2 Memory usage can be a little intensive

[Andrew Rowbottom]

Explore mechanisms for reducing the memory required to
produce a high resolution interleaved image.

Current usage for 20 100Mb images could easily be
expected to be 2Gb! If printed so that each source pixel
has a position on the destination. Indeed if printed that
way each source pixel will map onto 1 wide by 20 high,
which will require 20*20*200Mb or 20Gb!