We do have info.magnolia.imaging.util.ColorConverter, and it is used by info.magnolia.imaging.operations.text.TextStyleTransformer, but somehow we're missing the ability to convert all colors.

This might be due to the fact we can't globally register converters for types, except by modifying info.magnolia.content2bean.impl.Content2BeanTransformerImpl#Content2BeanTransformerImpl, which is where we could register a org.apache.commons.beanutils.Converter. The imaging module might get away with globally (statically) register a converter, but I'm not convinced this will work, since Content2BeanTransformerImpl is probably already initialized by then.