In video, which photometric measure represents brightness in an image?

• A. CHROMA
• B. LUMINANCE
• C. LUMA
• D. BRIGHTNESS

Answer: (C)

In video signal processing, brightness is carried by the luma component. Luma encodes the luminance information—the part of the image that conveys how bright each pixel should appear—separating it from color information stored in the chroma channels. This separation lets you adjust brightness and contrast without affecting color, and it aligns with how video formats (like Y'CbCr) represent a image for display. Luminance is a physical measure of light intensity, related but not the labeled video channel. Chroma holds color data, and a general term like brightness isn’t a standardized video signal component. So, the brightness in a video image is represented by the luma channel.