Retinol dehydrogenase with a clear preference for NADP. Oxidizes all-trans-retinol, but seems to reduce all-trans-retinal with much higher efficiency. Has no activity towards steroid. all-trans-retinol + NADP(+) = all-trans-retinal + H(+) + NADPH Cofactor metabolism; retinol metabolism. Localized on the outer side of the inner mitochondrial membrane. Belongs to the short-chain dehydrogenases/reductases (SDR) family.