What is the process called that changes the power of an electron beam to adjust brightness on a CRT screen?

The process that changes the power of an electron beam to adjust brightness on a CRT (cathode-ray tube) screen is known as intensity modulation. This involves varying the intensity of the electron beam as it strikes the phosphorescent coating on the inside of the CRT screen. By controlling the beam’s intensity, brightness levels are adjusted—making images appear lighter or darker based on the varying power supplied to the electron beam.

While options like brightness modulation and contrast adjustment refer to related concepts, intensity modulation specifically pertains to the control of the beam's intensity to directly affect the brightness of the displayed image. Color modulation, on the other hand, relates to adjusting colors rather than brightness, which clarifies why intensity modulation is the most appropriate term for this particular process.