What is a color filter used for in optical applications?

A color filter is specifically designed to absorb certain wavelengths of light while allowing others to pass through. This selective transmission is fundamental in various optical applications, such as photography, theater lighting, and scientific instrumentation. By controlling which colors of light are permitted to reach the observer or sensor, color filters can modify the appearance of objects and enhance visual effects.

For instance, a blue filter will absorb wavelengths of light that correspond to colors other than blue, thereby transmitting primarily blue light. This characteristic is crucial for achieving specific visual results or isolating certain wavelengths in experiments.

The other options, while they pertain to different aspects of optics, do not accurately describe the primary function of a color filter. Reflecting all wavelengths would not allow for any color discrimination, magnification does not relate to color filtering, and enhancing contrast usually involves techniques beyond the scope of what a color filter alone can achieve.