Simplify the following text for a Grade 10 native English-speaking person.
Original: The color of a pixel can be stored by using a combination of red , green and blue ( RGB ) but other combinations are also possible , such as cyan , magenta , yellow and black ( CMYK ) .
Simplified: The intensity of each pixel is variable . In color image systems , a color is typically represented by three or four component intensities such as red , green , and blue , or cyan , magenta , yellow , and black .