Transmittance control apparatus

A transmittance control apparatus comprising:

• processing circuitry configured to:
• identify, based on display information indicative of a target for display, a degree of lightness of the target for display;
• identify a lightness level of an environment in which a see-through display is disposed;
• and
• at a first timing at which a transmittance of the target for display is controlled, control the transmittance of the target for display on the see-through display based on a maximum lightness level of the environment during a first period prior to the first timing and on the degree of lightness of the target for display, by using an association among the degree of lightness of the target for display, the lightness level of the environment, and the transmittance of the target for display,
• wherein the maximum lightness level of the environment during the first period is indicated by an environment-lightness information set among a plurality of environment-lightness information sets,
• wherein the association includes a first association and a second association,
• wherein the first association defines a relationship such that when the degree of lightness of the target for display does not fluctuate and the lightness level of the environment fluctuates within a range not exceeding a first lightness level, the transmittance of the target for display on the see-through display is reduced in accordance with an increase in the lightness level of the environment, and
• wherein the second association defines a relationship such that when the degree of lightness of the target for display does not fluctuate and the lightness level of the environment fluctuates within a range exceeding the first lightness level, the transmittance of the target for display on the see-through display is increased in accordance with an increase in the lightness level of the environment or is maintained regardless of an increase in the lightness level of the environment.