In opacity, what is used to define which parts of an object are visible through a grayscale map?

In opacity, what is used to define which parts of an object are visible through a grayscale map?

• A. Color image
• B. Alpha channel
• C. Texture map
• D. Grayscale image

Answer: (D)

Opacity is controlled by a grayscale image that defines per-pixel visibility on a surface. In this setup, the brightness of each pixel determines how opaque or transparent that part of the object will be: white areas stay fully visible, black areas become fully transparent, and gray levels create partial transparency. This per-pixel control is exactly what a grayscale map provides for an opacity channel, letting you carve holes or soft edges without changing the color information. A color image would only set color, not transparency. A texture map is any image used on a surface, and while grayscale images can serve as texture maps, the specific use described—mapping visibility via brightness—relies on the grayscale image as an opacity map. An alpha channel is another method to store transparency, but the question focuses on the grayscale map approach for defining visibility.

Opacity is controlled by a grayscale image that defines per-pixel visibility on a surface. In this setup, the brightness of each pixel determines how opaque or transparent that part of the object will be: white areas stay fully visible, black areas become fully transparent, and gray levels create partial transparency. This per-pixel control is exactly what a grayscale map provides for an opacity channel, letting you carve holes or soft edges without changing the color information.

A color image would only set color, not transparency. A texture map is any image used on a surface, and while grayscale images can serve as texture maps, the specific use described—mapping visibility via brightness—relies on the grayscale image as an opacity map. An alpha channel is another method to store transparency, but the question focuses on the grayscale map approach for defining visibility.