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What Is The Rainbow Effect In DLP Projectors?


Projectors have gained popularity and are widely used. This is due to the great viewing experience they offer amongst other things.

Contributing to the viewing experience is the color accuracy of projected images. Accurate color representation increases the desirability of projectors.

A lot of manufacturers now give priority to color quality and integrity. They do this to ensure that the projected image looks exactly like it should.

This is especially important for projectors used in the film and graphics industry where color representation is important.

DLP projectors are at the forefront of color accuracy. The technology is not without its drawbacks, however.

This article will explain the Rainbow effect which is common with DLP projectors. To learn how to reduce this effect, read on.

What is the Rainbow Effect?

rainbow effect image of DLP projector

In most projectors with the 1-chip DLP technology, colors are projected sequentially with use of a rotating color wheel.

Sometimes, this causes a percentage of the audience to see a phenomenon referred to as the “Rainbow Effect”.

Imagine the Rainbow effect occurring in your home theatre or during a work presentation. Nothing ruins a good projection like flashes of color being displayed on the screen.

You will notice momentary flashes of red, green and blue shadows. This is known as the DLP Rainbow Effect or color breakups.

This phenomenon is noticeable when bright objects show up against darker backgrounds during projection. To the viewer, flashes of color are seen around the image.

The images displayed on the projector screen should have crisp edges. Instead, the edges have color fringes that resemble rainbows.

It becomes very obvious in two cases:

  • when the viewer’s eyes move quickly over the lighter areas of the projected image
  • when video scenes showing fast movements are projected.

How is the Rainbow Effect Formed?

a DLP projector using separate chips generate colors red, green, blue

DLP projectors that use single chips are most susceptible to the rainbow effect.

The phenomenon is seen because these projectors use separate chips that generate colors in sequence (red, green, then blue).

This means that the projector displays one color before proceeding to display the next.

Regularly, the color generation occurs at a very fast rate. This makes the switching undetectable to the viewer’s eye.

The speed allows viewers to see all colors produced as a single image. They do not view the colors one after the other.

On cheaper or older DLP projectors, the color generation is carried out with the aid of a rotating color wheel.

The DLP rainbow effect is noticed on projectors that make use of this medium of color generation. This occurs when the wheel is not as fast as it should be.

It is most noticeable when a white or bright object (such as a lit bulb) is displayed against a dark background.

White (or almost white) images are represented by flashing all three colors (red, green, and blue) at the same time. This makes the rainbow effect more visible.

How Do I Fix/Reduce the Rainbow Effect on My Projector?

fix the rainbow effect of DLP projectors

Viewers who aren’t highly susceptible to the DLP rainbow effect can ignore it as time passes. With constant practice, they may even stop noticing it completely.

In these cases, the viewer only notices the effect while making vigorous head movements.

The effect also becomes noticeable when a light object contrasts sharply against a dark background.

You may reduce the extent to which you notice the Rainbow effect by:

  • Reducing the projector brightness
  • Lowering bulb power 
  • Turning on ambient lighting to a moderate degree

For most people, the brain will adjust to seeing the rainbow effect and processing DLP. With time, it will become barely noticeable.

There is the minority who are more susceptible and experience a more serious reaction to the DLP and the Rainbow effect. Most of the effect will reduce as they adapt.

However, the severity of one’s reaction to the Rainbow effect may call for more than adaptation.

One way to reduce the rainbow effect without adapting to it is with the aid of filter softwares.

The rainbows are very noticeable during high light-dark contrast in images. Hence, softwares that filter videos such as Ffdshow (with a temporal smoothing value of 4) are helpful.

The software helps to reduce the rainbow effect by smearing the frames. The rainbows get replaced by shadow effects due to the preset temporal smoothing.

This method completely eliminates viewing discomfort, eye strain and nausea. However, the screen might look like a plasma screen.

This is due to the slowing down of the pixel updates caused by the smear. Also, the image quality might be slightly reduced.

Some people have trouble with DLP technology as a whole. Their brain and vision are unable to process the way it works.

This problem also lessens with time as the brain acclimates.

FAQs

Frequently Asked Questions on dark background

1. Do Laser Projectors Have the Rainbow Effect?

Laser projectors use a laser light source to create their enlarged images.

Laser projectors may use one of different projection technologies including the DLP or LCD technology.

The primary cause of the Rainbow effect is the sequential production of color in projectors. This technology is a quality of DLP projectors.

Not all laser projectors use DLP technology. Those of them that do so are prone to the Rainbow effect.

2. Can Everyone See the Rainbow Effect?

The rainbow effect doesn’t affect a large number of projector viewers. Although, for the affected group of people, it can be quite disturbing.

Noticing this phenomenon is subjective. This is because some people are more sensitive than others at seeing rainbows.

For those who are highly susceptible, the rainbow effect poses a great problem. More often than not, their only option is to get a projector that doesn’t have this problem.

Some others who are mildly susceptible only notice the color flashes when they focus on them.

Fortunately, a lot of viewers do not witness the phenomenon at all. However, if you do, there are ways to minimize it which have been tested by other viewers.

Conclusion

The rainbow effect in DLP projectors exists due to the slow color production in rotating color wheels.

This greatly affects the viewing experience and discomforts viewers who are highly susceptible.

Although it is possible to adapt to and stop noticing this phenomenon completely, filter softwares can be used to filter the projected images and eliminate the discomfort.

Read more: 10 Most Common Projector Display Problems


1 thought on “What Is The Rainbow Effect In DLP Projectors?”

  1. ALL single-DLP projectors, whether they are lamp, LED, or laser, with or without a color wheel, will ALWAYS produce rainbow effect (RBE). The ONLY way to completely eliminate RBE is by using 3-chips, one each for R, G, B. So much confusion is being percolated on the internet, like a projector with 3 lasers will not have RBE; wrong. Even if a projector has 3 lasers, as long as it is only single-DLP, it will ALWAYS still produce hateful sickening RBE.

    Reply

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