This works wonderfully! With an image size 123456x123456, I made this happen: <a href="http:&#x2F;&#x2F;i.imgur.com&#x2F;2Dgrazj.png" rel="nofollow">http:&#x2F;&#x2F;i.imgur.com&#x2F;2Dgrazj.png</a><p>I killed it at about 25GB memory usage, who knows how high it would have climbed otherwise.