Image Magick Tips and Tricks:

In order to convert large images one can limit the memory of convert process.
Also if your /tmp folder is not big enough you can specify swap directory from command line:

convert -limit memory 320000mb -monitor -debug cache -define registry:temporary-path=/scratch/02tmp tileimg.ppm tileimg.mcp

If convert has an OpenMP palatalization enabled you can set number of threads with:

-limit thread 1

For 48000x48000 image   it uses about 900Gb for caching.
In example I use mcp native imagemagick cache format. If same image will be analysed/converted many times this format is recommended.