Creating color information with a color camera is far from trivial: In its simplest form, a regular color camera requires the information from 2x2 pixels to calculate the color value of a pixel from a so-called Bayer pattern – the so-called 2x2 debayering. Since this is an interpolation, the results for a 2x2 matrix are relatively poor. A 3x3 or higher matrix is used more often. A monochrome camera gets its information about each pixel in a much more linear fashion, namely 1:1 from its pixel array.
But the human eye is designed as a universal tool. We don’t always need our ability to see colors; often the information provided by only the brightness values of the perceived objects is enough. It’s very similar with image processing.
In many cases the effort of a color depiction with a color camera is unnecessary and the technical difficulties associated with it can be avoided after a careful analysis of the application requirements.
Many applications can dispense entirely with color information in the image processing chain. In others, a type of selective color information can be created with colored lighting or color filtering and a monochrome camera; for example, green areas on red objects appear black when the light used was red.