At a first time point, a light amount adjusting unit stores the brightness of illumination light as a first brightness, and stores the light intensity of each color component of the illumination light as a first light intensity. A gain adjusting unit sets a gain value of at least one of the individual color components to be a maximum value, and stores the gain value as a first gain value. At a second time point after the first time point, the light amount adjusting unit calculates a ratio between a second light intensity and the first light intensity. The gain adjusting unit corrects the gain values based on the ratio between the second light intensity and the first light intensity.

At a first time point, a light amount adjusting unit stores the brightness of illumination light as a first brightness, and stores the light intensity of each color component of the illumination light as a first light intensity. A gain adjusting unit sets a gain value of at least one of the individual color components to be a maximum value, and stores the gain value as a first gain value. At a second time point after the first time point, the light amount adjusting unit calculates a ratio between a second light intensity and the first light intensity. The gain adjusting unit corrects the gain values based on the ratio between the second light intensity and the first light intensity.

A system includes a spatial light modulator (SLM) and a circuit including a processor. The SLM includes pixel elements. The circuit is configured to convert M primary video signals to N multi-primary video signals. The circuit is configured to use a first multi-primary video signal to derive a first additive offset to a first primary video signal, to use the first multi-primary video signal to derive a second additive offset to a second primary video signal of the M primary video signals, to add the first additive offset to the first primary video signal, to add the second additive offset to the second primary video signal, and to derive a bit plane based on the first primary signal having the first additive offset added thereto and to transmit the bit plane to the SLM to selectively control on and off states of the pixel elements of the SLM.