false color highlights seem to be an issue frequently, so here’s some quick faq about it. alexandre, please excuse all the outward references ;)
why are my highlights magenta? that’s how the sensor works. it collects a couple of photons, at some point it fills up and rejects to deliver any more useful information past this point. unfortunately that doesn’t happen at the same time for all color channels.
how does the sensor work?
This is a companion discussion topic for the original entry at https://www.darktable.org/2012/07/magenta-highlights/