A wide range of light that may be detected with a digital camera — all colors of visible light, the near Infrared (IR), and ultraviolet (UV)— enter the camera through the lens.
Since most digital cameras have a glass lens, most UV is absorbed before it enters the camera .
The IR filter blocks nearly all infrared light from reaching the camera's sensors, unless the filter has been removed. Even with the IR filter in place, intense near infrared light sources will be seen by the digital camera - such as the LED on most remote controls.
The visible light passes through the infrared blocking filter of the camera’s internal light sensor. Visible light then passes through a series of color filters which control what color light reaches an individual light sensor. Red filters block/absorb/subtract green and blue light, so red light reaches the sensor. The sensors convert light to electricity, with the greater intensity of light creating a greater number of electrical charges. This sequence of filters coupled with the sensor translates the light traveling from the picture’s subject into measurable intensities of red, green, and blue light.