2024-01-29
How to control the color of LED lamps and achieve color mixing?
How to control the color of LED lamps and achieve color mixing?
About additive color mixing
LED lamps use multiple light sources to obtain a variety of colors and intensities. For the performing arts lighting industry, the addition of mixed colors has been a commonplace. For years, practitioners have used lamps with color filters to project the same area on the sky, which is not easy to control. The first smart luminaire I used was a spotlight with three MR16 light sources, each with red, green and blue filters. In the early days, such lamps had only three DMX512 control channels, and there was no independent strength control channel. So it's hard to keep the color the same during the dimming process. Usually, the computer lamp programmer will also set up a "light out color change" in order to easily extinguish the lamp.
Color control and definition
If the user does not use a pure DMX value to control the intelligent luminaire, but with some abstract control mode, a virtual strength value can be used. Even if the manufacturer specifies that the luminaire uses three DMX channels, the abstract control mode can be assigned four handles to control: the intensity value and three color parameters.
Here I wrote "3 color parameters" instead of red, green, and blue, because RGB is just one way to describe color. Another way to describe it is hue, saturation, and luminance -HSL(some people call it intensity or lightness, not brightness). Another description is hue (hue), saturation (saturation) and brightness (value)-HSV. Value is also often referred to as brightness, which is similar to Iumlnance. However, HSL and HSV have very different definitions of saturation. For simplicity, the author defines hue as color and saturation as the amount of color in this article. If the "L" is set to 100%, it is white, 0% is black, then 50% L is a solid color with saturation l00%. For "V", O% is black and l00% is a solid color, at which point the saturation value must make up for the difference.
Another effective way to describe them is CMY, they are three primary colors and use subtraction to mix colors. If white light is emitted at first, then two filters can be used to obtain red: magenta and yellow; They remove the green and blue components of white light, respectively. Usually, LED color-changing lamps do not use subtraction color mixing, but this is still an effective way to describe color.
In theory, when controlling leds, it should be possible to adjust the intensity and one of RGB, CIMI.HSL, or HSV (there are some differences between them).
Here I wrote "3 color parameters" instead of red, green, and blue, because RGB is just one way to describe color. Another way to describe it is hue, saturation, and luminance -HSL(some people call it intensity or lightness, not brightness). Another description is hue (hue), saturation (saturation) and brightness (value)-HSV. Value is also often referred to as brightness, which is similar to Iumlnance. However, HSL and HSV have very different definitions of saturation. For simplicity, the author defines hue as color and saturation as the amount of color in this article. If the "L" is set to 100%, it is white, 0% is black, then 50% L is a solid color with saturation l00%. For "V", O% is black and l00% is a solid color, at which point the saturation value must make up for the difference.
Another effective way to describe them is CMY, they are three primary colors and use subtraction to mix colors. If white light is emitted at first, then two filters can be used to obtain red: magenta and yellow; They remove the green and blue components of white light, respectively. Usually, LED color-changing lamps do not use subtraction color mixing, but this is still an effective way to describe color.
In theory, when controlling leds, it should be possible to adjust the intensity and one of RGB, CIMI.HSL, or HSV (there are some differences between them).
About LED color mixing
The human eye can detect light with a wavelength of 390nm to 700nm. The original LED lamps only used red (about 630nm), green (about 540nm) and blue (about 470nm) leds. These three colors do not mix every color that the human eye can see. Figure l is a hypothetical region of the proposed RGB model based on the entire visible spectrum.
The three vertices of the triangle fall within a highly saturated red, green, and blue area. By changing the power emitted by each LED chip, you can get any color in the color gamut, but this is only a theory, in fact, the color mixing effect is affected by many factors. For example, the exact wavelengths of red, green, and blue vary from lamp to lamp, and there can be huge differences between them.
Gamut describes not only tone, but also intensity and saturation. If you do a quick Google search for "colorgamut" (colorgamut), you will see circles, rings, cubes, cones, and even fruit shapes, all of which attempt to show the three-dimensional relationships of HSL.
The three vertices of the triangle fall within a highly saturated red, green, and blue area. By changing the power emitted by each LED chip, you can get any color in the color gamut, but this is only a theory, in fact, the color mixing effect is affected by many factors. For example, the exact wavelengths of red, green, and blue vary from lamp to lamp, and there can be huge differences between them.
Gamut describes not only tone, but also intensity and saturation. If you do a quick Google search for "colorgamut" (colorgamut), you will see circles, rings, cubes, cones, and even fruit shapes, all of which attempt to show the three-dimensional relationships of HSL.
Add more color
With the technological innovation of LED, the price decline and other changes, more and more manufacturers have entered this market. Lighting designers are increasingly looking forward to this new light source, and the requirements for luminaires' brightness and control color consistency are also increasing. New LED colors such as white, amber, cyan and violet were introduced. At first, the most popular combination was RGBA, which added amber chips. This makes the color gamut shape more like a rectangle than a triangle.
Another variant is the RGBW, which comes with a wide spectrum of white leds. There are new lamps that add white and amber (RGBAW) on top of RGB.
With the continuous progress of LED technology, chip manufacturers have also successfully produced deep red, cyan and magenta blue leds. These colors have been applied to the 7 color system (deep red, red, amber, green, cyan, blue and magenta), thus expanding the color gamut and providing designers with more colors.
Controlling so many chips can be laborious; Various combinations of the power of each chip can obtain the same color point in the color space.
Another variant is the RGBW, which comes with a wide spectrum of white leds. There are new lamps that add white and amber (RGBAW) on top of RGB.
With the continuous progress of LED technology, chip manufacturers have also successfully produced deep red, cyan and magenta blue leds. These colors have been applied to the 7 color system (deep red, red, amber, green, cyan, blue and magenta), thus expanding the color gamut and providing designers with more colors.
Controlling so many chips can be laborious; Various combinations of the power of each chip can obtain the same color point in the color space.
How to control these leds
Due to the further development of LED technology, the control has become more and more complex. Fortunately, some modern control systems can drive any type of color system in a very simple way. In addition to intensity, the user is given different color parameters: RGB, CIMy.HSL and HSV.
The author examines these possibilities through a real-life example. For example, a designer working on a musical is using mixed-color lamps to dye the canopy.
The stage needed to create a sunset scene, and the designers wanted to change from amber to pink. RGB color space is used, cuel is amber (R=lOO%, G=60%, B=O%), cue2 is pink (R=100%, G=0%, B=60%).
The author examines these possibilities through a real-life example. For example, a designer working on a musical is using mixed-color lamps to dye the canopy.
The stage needed to create a sunset scene, and the designers wanted to change from amber to pink. RGB color space is used, cuel is amber (R=lOO%, G=60%, B=O%), cue2 is pink (R=100%, G=0%, B=60%).
