单色光是指单一颜色（精确定义的频率或波长）的光。当可见光谱范围内的单色光被感知为一种颜色时，这就是光的光谱颜色。
单色光在照亮（多）彩色测试物体和/或背景的情况下非常重要。我们的目标始终是提高与白色或其他颜色的对比度，从而提高测试对象与其他对象和/或背景（例如，食品工业中的蓝色传送带）的区分度。
在与彩色物体相关的工业图像处理中，使用彩色照明非常重要。不同的光色代表不同的波长，无论它是来自照明的光还是物体的反射光。
如果照明光的颜色和物体的颜色大致相同（即它们的波长大致相同），单色采集图像中的物体就会显示为非常亮或全白（因为物体在入射光中对该波长的反射特别好，或在透射光中对该波长的吸收特别差）。相反，如果使用补色（色圈中的对立色），则物体会显示为非常暗甚至全黑。
合适的灯光颜色（与物体颜色相关）可以提高对比度，帮助突出或隐藏结构。
图色环，Johannes Itten，1961 年，公有领域
单色传感器的一个优势是可以确定光谱，甚至是近紫外线和近红外线，而彩色传感器只对红、绿和蓝光敏感！
Monochromatic light is light of a single color (a precisely defined frequency or wavelength). When monochromatic light in the visible spectral range is perceived as a color, this is known as the light's spectral color.
Monochromatic light is important in instances where (multi-)colored test objects and/or backgrounds are illuminated. The goal is always to increase the contrast with respect to white or other colors, and consequently to increase the test object's segmentation from other objects and/or the background (for example, a blue conveyor belt in the food industry).
The use of colored lighting is of great importance in industrial image processing in connection with colored objects. Different light colors represent different wavelengths, regardless of whether it is the light from lighting or the reflected light of an object.
If the lighting color and the color of the object are approximately the same (i.e. their wavelengths are approximately the same), the object in a monochrome acquired image is displayed as very bright to completely white (since the object reflects this wavelength particularly well in incident light or absorbs it particularly badly in transmitted light). Conversely, with a complementary color (opposing color in the color circle), the object can be displayed very dark to completely black.
The right lighting color (in relation to the object color) can improve contrast and help highlight or hide structures.
Fig.: Color circle per Johannes Itten, 1961, in the public domain
One advantage of monochromatic sensors is that the light can determine the spectrum, even for near-ultraviolet and near-infrared light, while color sensors are only sensitive to red, green and blue!