What Determines The Color Reproduction & Performance Of A Projector

Last Updated October 18,2018

The brightness, resolution, contrast ratio, and color reproduction are points that people often pay much attention to when choosing a home projector, and the color reproduction is usually ignored by many guys because it is subjective and its parameters are hard to understand.

In fact, the color is the most direct thing that influences people’s mood: while seeing blue sea and sky, green trees and thickets, pure white pear flowers, and orange-red begonia flowers we feel pleasant, and Spider man’s red and blue suit, Hulk’s green skin, and Iron man’s red armor, if these color can’t be accurately reproduced, are they still the heroes we know?

So what determines a projector’s color reproduction?

Simply put, it is the color gamut. A projector’s color gamut is the range of color it can show, the wider the color gamut, the more color it can reproduce. There are many standards for color gamut like sRGB, Rec.709, NTSC, DCI-P3, Adobe RGB, etc., and different standards have different color ranges as shown below.

Appearcely, a projector which meets DCI-P3 standard has more accurate color revivification and more forceful color expression, and even the two projectors under the same color gamut standard may have different color coverage because the degree of optimization done varies.

What, then, determines the color gamut of a projector?

The color gamut of a projector is mainly determined by the light purity of the illumination source employed by the projector.

Traditional projectors often utilize UHP lamp(ultra high pressure lamp, usually mercury arc)  or Xenon lamp, and such type of lighting sources produces visible light by electrifying a bulb containing a certain rare gas to make the rare gas ionize, and this visible light is not pure and comprised of lights at different wavelengths (or different colored light), and needs to be filtered to get the Red, Green, and Blue light. The course of filtering is difficult to control so the color coverage of lamp projectors varies.

LED’s(light-emitting diode) change this situation effectively. The LED is a p–n junction diode that emits light when a suitable current is applied to the leads. Like a UHP lamp, The color of light emitted from an LED is not monochromatic also, but the spectrum is narrow with respect to human vision, and for most purposes the light from a simple diode element can be regarded as functionally monochromatic, so the LED projector’s color gamut is remarkably improved compared with the lamp projector.

JMGO N7L Portable Smart LED Projector

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The color of light emitted from a laser is both monochromatic and coherent, thus a laser-based projector scales new heights in color coverage and accuracy, moreover, since the laser has a more constant performance there is no color fading and brightness degradation after a prolonged use.

JMGO SA Smart Laser Projector

For DLP projectors, the color wheel is another factor that influence a projector’s color gamut.

The color wheel is mainly applied in DLP projectors and plays a role in color filter and manipulation. It is a high-speed rotating disc with a very thin metal layer on the surface.The metal layer utilizes the vacuum coating technique and different parts of the layer are designed to different degrees of thickness according to the wavelengths of the colors in the spectrum to filter out desired colors like red, blue, green, and others. When the color wheel rotates between red, blue, and green, the DLP chip sends the correct pattern of light. Because the images go on and off the screen so quickly, the brain puts them together into one full-color image. This is similar to how the brain perceives the series of still images in a movie as an actual moving picture.

The first color wheels had three parts (three-segment), the familiar RGB colors, blue, green and red. Also roamed with speed 60 revolutions per second (3600rpm) named speed 1x. Later, to achieve higher color gamut coverage and more accurate color reproduction, there appeared color wheels with 4 segments, 6 segments, 7 segments and speed of rotation 2x, 3x, 4x, etc. Today’s high-end DLP projectors usually employ the 6-segment RGBRGB color wheel spinning at 240 revolutions per second.  

I hope this short article was quite informative and enabled you to judge a projector’s color reproduction and performance accurately.


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