LED lighting system - what is it?

RGB LED lighting system - what is it?

The RGB color system is one of the models of color space (i.e. a conventional set of different colors). There are more such color spaces (e.g. CMYK, HSL, YUV, etc.) and they are included in international standards. They are used in graphics and in various industries to facilitate recognition and repeatability of colors. The RGB system is one of the most popular. Its name derives from the first letters of the English names of colors: R - Red - red, G - Green - green and B - Blue - blue. It is a color model used to generate colors through projection devices, i.e. those that emit light. Originally it was invented for analog display devices, but in today's world it has settled in well on digital devices. It is used by LCD TVs, projectors, digital cameras and RGB lighting controllers. To a large extent, it is based on the imperfections of the human eye, allowing by mixing different values ​​of individual color components to get the impression of displaying a different color than the basic components. In practice, the RGB LED lighting system consists in using either three LEDs in the primary colors or one multicolor LED (with 3 chips inside 3 basic colors) and appropriate control of their brightness. The RGB color model is, unfortunately, a purely theoretical model. In practice, this means that in each device that uses its color palette, there may be differences in shades when generating individual colors. These differences deepen additionally in LED lighting due to different proportions of the actual brightness of individual color components in RGB diodes. In practice, this means that depending on the RGB LED strip used, we can obtain completely different shades of color. What's more, there may be differences in shades even within one LED strip. LEDs in the RGB system are most often digitally controlled by means of PWM modulation. Usually, a 24-bit color description method is used, with 8 bits for each of the three color components. As a result, individual component colors can take one of the values ​​on a scale from 0 to 255. Each of the values ​​indicates the brightness of displaying a particular color. At the value 0, the color does not light at all, and at the value of 255 it shines with maximum brightness. By mixing three components of colors with different brightness’s, we obtain individual colors. For example, mixing colors with the values ​​of R: 255 and G: 255 B: 0 will give us a yellow color, and colors with R values: 255 G: 0 B: 255 gives us a pink-purple color called magenta from English. Mixing all components with a maximum value of 255 theoretically should give us a white color, but the scattering of RGB diode parameters or differences in brightness in individual LEDs in RGB colors often requires that the proportions in the controller must be corrected to obtain a white color. By reducing each of the component values ​​in parallel and proportionally, we will not get a change in color, only a change in brightness. However, due to the 8-bit character of each color (i.e., low accuracy) in real devices based on the RGB system, there may be small differences in shades of dimmed colors when the intensity changes. Usually, however, these are not differences large enough to be a problem. The average observer most often is not able to see the difference in shades of a given color at changing brightness. If, however, in the RGB system, we change each of the values ​​of individual colors by the same number of steps (instead of proportionally), we get not only a change in brightness but also a change in color. The biggest problem with the RGB system in LED lighting is the large dispersion of LED parameters, and hence the difficulty in obtaining color reproducibility. The vast majority of popular LED strips have a color dispersion of up to 10-15%, which may already be noticeable to the naked eye. Unfortunately, technological difficulties in producing RGB LEDs with low parameter spread are still very large and because of this, very good quality LED strips with a spread of parameters at the level of individual percentages usually have a drastically higher price. It can be up to several times higher than a typical RGB tape.