Photographic lighting bitmap, high-key, medium-key, low-key. How to fight separately? A light bitmap is required.

High-profile: brighten the white background, make one or two side backlights as the main light, fill the front light, and expose according to the front.

Intermediate tone: the front side light is the main light, the background is properly treated, and the exposure is carried out according to the main light.

Low-key: black background, the main body with strong light modeling, high-light exposure, appropriate to add half a step.