Astanga Hrudaya
चायाङ्गात्सम्भवत्युक्ता प्रतिच्चायेति सा पुनः । वर्णप्रभाश्रया या तु सा चायैव शरीरगा ॥ ४३ ॥
through the medium of sunlight (rays), mirror, water etc, is called pratichaya (shadow image) (it is not connected with colour and radiance) that which is connected to these colour and radiance are related to the body only and they are called as chaya.
english translation
cAyAGgAtsambhavatyuktA praticcAyeti sA punaH । varNaprabhAzrayA yA tu sA cAyaiva zarIragA ॥ 43 ॥
hk transliteration by Sanscript