Another quick fix documented here simple because it may help me (or someone else of course) in the future.
For a project I'm working on right now I need to crop an image using ImageMagick. We're using the commandline instead of Imagick because we need to execute a custom command with a lot of extra options for this specific action, since the image will eventually be used for high-quality printing. As I was testing the command, tweaking the parameters, I eventually ended up with an error:
convert: delegate library support not built-in `white' (LCMS) @ warning/profile.c/ProfileImage/853
It turns out this was very simply to solve: I used homebrew to install imagemagick, and I installed it simply by doing:
brew install imagemagick
Apparently, this is wrong. At least when you want to specify your own profile (for instance by using -profile /path/to/sRGB_IEC61966-2-1_black_scaled.icc). The solution? Install it --with-little-cms:
brew install imagemagick --with-little-cms
With thanks to clee704 on Github who came up with this solution.