Created attachment 8354 [details]
Unified patch (git diff)
This patch adds an option (-@) to pdfdraw that can be used optionally to decrease the resolution parameter, such that the output file dimension does not exceed a given value in Megapixels.
We will not be taking this patch on as we can't see that this is generally useful.
We have recently added -w, -h and -f flags that discussions on irc suggest would suit your purpose too.