أَحْمَرُ — أَشَدُّ حُمْرَةً
Aḥmar is a colour adjective, not by itself a regular comparative. Ašaddu ḥumratan supplies the comparison.
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Why Not Directly from a Colour?
Ism al-Tafḍīl: Formation, Comparison, Agreement and Parsing
أَحْمَرُ — أَشَدُّ حُمْرَةً
Aḥmar is a colour adjective, not by itself a regular comparative. Ašaddu ḥumratan supplies the comparison.