Head-mounted display devices and adaptive masking methods thereof

An adaptive masking method for a head-mounted display device comprising a display system and a light modulator which is positioned between the display system and a surrounding environment, and comprises an array of pixels, the adaptive masking method comprising:

• configuring the display system to selectively displays a first content to be visually recognized as being superimposed on a scenery of the surrounding environment, or not display the first content;
• configuring a portion of the pixels to modulate light to present a display of a second content;
• configuring the rest of the pixels to be substantially transparent to light;
• detecting, via an ambient light sensor, a lighting condition of the surrounding environment;
• and
• adjusting, according to the lighting condition, at least one of a first power level applied to allow the display system to display the first content, and a second power level applied to allow the light modulator to modulate light,
• wherein the adjustment of at least one of the first power level and the second power level comprises:
• increasing the second power level and decreasing the first power level when the lighting condition indicates that a brightness is greater than a predetermined threshold, and increasing the first power level and decreasing the second power level when the lighting condition indicates that the brightness is lower than the predetermined threshold.