We aimed to verify painters' empirical rules in painting portraits from the perspective of face perception. In particular, we examined the effects of lighting on perceiving impressions and facial expressions of a depicted person by using portrait paintings with various lighting conditions of contrast (high, low) and position (left, right). Viewers rated their impressions of the people in the portraits and those people's expressions using 7-point scales. Impressions regarding likability or attractiveness were stable regardless of the lighting conditions, while the other impressions differed among the lighting conditions. Positive emotions were perceived more strongly in paintings with low contrast, whereas negative emotions were perceived more strongly in paintings with high contrast. Overall, these results suggest that lighting has a systematic effect on face perception even in portrait paintings. We propose that the current study provides empirical evidence of painters' implicit knowledge.