Pigment-based number case yog ib hom number case uas siv rau xim ntawv thiab lwm qhov chaw.Pigments yog cov khoom me me ntawm cov khoom raug tshem tawm hauv cov kua lossis roj nruab nrab, xws li dej lossis cua.Nyob rau hauv cov ntaub ntawv no, cov xim yog tov nrog ib tug roj-raws li cov cab kuj.