Today, I was combining a set of images like so:

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$ convert -append figP*.png out.png

when I got error stating that cache resources exhausted. I was first surprised because it was the same set of images I combined a couple of days before EXCEPT that I significantly increased their resolution. So I googled the error message and found this issue on the GitHub repository of ImageMagick.

Well, turns out it was not a issue at all, I simply needed to change the memory limit as explained here and well summarized in the issue:

[…] increasing the memory limit in /etc/ImageMagic-6/policy.xml works for me.

So, all I had to do was to go to /etc/ImageMagick-6 (with a k, there is a typo in the original comment quoted above) and modify policy.xml: I changed

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<policy domain="resource" name="memory" value="256MiB"/>

for

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<policy domain="resource" name="memory" value="1GiB"/>

Given my 16GB of memory, I thought it was ok to bump up to 1GB my 😉!