Glossary of Terms

Glossary of Terms

4K DLP With XPR Technology

Most consumer 4K DLP projectors utilize a single Texas Instruments (TI) Digital Light Processing (DLP) chipset with an arrangement of highly reflective aluminum micromirrors known as the DMD to deliver 4K UHD (3840×2160 pixels) displayed resolution.

The XPR Technology allows a DLP to display a 4K image. Texas Instruments states that “XPR Technology achieves true 4K by producing 8.3 million distinct pixels regardless of the DMD chip’s number of native pixels. XPR quadruples the 0.47-inch DMD chip’s native 1920×1080 pixels to generate 4K (8.3 million pixels) onscreen resolution due to its lightning-fast pixel shifting speed. This is why Projector Reviews list the native resolution of many 4K DLP projectors as 1920x1080x4.

So while a DLP imager may contain less than 8.3 megapixels, every pixel’s image is rapidly shifted, allowing each one to do the job of multiple pixels. When it comes to pixel shifting, faster is better. The pixel wobbling is done so fast that it fools your eyes into seeing up to four times the projector’s native resolution.

The Consumer Technology Association (CTA)® states that 4K UHD must produce 8.3 million distinct pixels on the screen, which is four times the resolution of Full HD 1080p. Furthermore, the CTA states, “With more than 70 committees, subcommittees and working groups and roughly 1,100 participants, the CTA Technology and Standards program maintains an unmatched reputation as a credible and flexible standards-making body accredited by the American National Standards Institute (ANSI).”

There is a lot of debate about 4K capable DLP versus native 4K LCOS-based projectors; at Projector Reviews, we are more than comfortable with the CTA’s explanation on 4K UHD and setting industry standards with the well-written statement they provided.

Based on years of testing both 4K capable DLP projectors and native 4K projectors, we can testify that is nearly impossible to see a difference in resolution between these two 4K solutions, especially from a normal viewing distance.

Ambient Light

Ambient light is a term that refers to the amount of light that is present within a room environment, which interferes with the contrast of the projector. That is light coming in from windows, or overhead lights that cannot be dimmed or turned off, resulting in the “washing out” of the projected image. For rooms with uncontrollable ambient light, such as most classrooms, conference rooms, and museums, there is a workaround: Ambient Light Rejecting Screens (click here to learn more about Ambient Light Rejecting Screens)

A video image in a dark room projected by the Epson PowerLite 1785W

Image taken in a dark room.

 

A video image in ambient light projected by the Epson PowerLite 1785W

Image taken in a bright room with ambient light.

Ambient Light Rejecting Screen

Ambient Light Rejecting screens started becoming popular less than a decade ago, and for good reason. They allow users to be able to project in rooms with a respectable amount of ambient light, filling a large screen with far less loss of contrast and color saturation than with traditional screens. This screen type, combined with far brighter projectors, has taken projectors out of darkened rooms and into the light. Whether in a classroom or auditorium, no longer does the room have to be made dark to be able to see the image.

From a practical standpoint that gives projectors a significant advantage over very large monitors in most environments. That’s because large monitors are still relatively small as they are only “affordable” up to about 71”-80”. A 100” monitor setup can easily cost 10 times that of a 100” projector and screen setup of really good quality.

In a perfect world, that means that using a projector with an ALR screen will “reject” ambient light from the room producing an image about as good as if there was no ambient light in the room. That, however, is to assume that the ambient light is not coming from near where the projector is positioned. Today (2020) fixed ALR type screens from recognized brands sell starting at under $1000 for a 100” size, while premium brands can cost twice that or more.

 

The least expensive projector in a bright room, with a good ALR screen can outperform other projectors costing far more, but with traditional screens.

 

Now a 3,000 lumen, standard throw projector in a fairly bright room using a 100” ALR screen may look a lot better than a 5,000, or even a 10,000 lumen projector on a regular screen. In a darkened room, of course, the brighter projectors will look much brighter. But, the least expensive projector in a bright room, with a good ALR screen can outperform other projectors costing far more, but with traditional screens.

There’s always a catch! In this case, two of them!

  1. To be effective at rejecting ambient light, that ambient light can’t be coming from anywhere near where the projector is placed.
  2. Ultra Short Throw projectors require special ALR screens specifically designed for UST.

With a great ALR screen, a projector ceiling mounted 12 feet back from a 100” screen (typical), ambient light coming from unshaded windows on either side of the screen will have almost zero effect on how the projected image looks. Close shades on those windows and leave the rest of the room the same, and you probably can’t tell the difference looking at the projected image. But, if those windows are in the back of the room, behind the projector, the ALR screen can do nothing, for to reject that ambient light it would have to also reject the light from the projector!

If the light is coming in from a back corner, then the ALR screen should still be pretty effective, and more so the further the ambient light is to the side. The same is true for overhead lights.  Ambient light from almost directly above the screen will be rejected, but if that light is closer to the projector – again, it can’t be.

 

Screen Innovations 100” Solo screen is an ALR type designed for UST projectors. Shown here at CEDIA, under lots of trade show ambient light.

 

Ultra short throw projectors cannot use an ALR screen designed for standard throw projectors, as those screens mistake the light from the projector as ambient light. This results in a completely washed out image. For this reason, if you’re pairing an ultra short throw projector with an ALR screen, you must choose one that is specifically designed for a UST projector.

 

Ambient light rejecting screen in a bright environment

ALR screens can be game changers in many business and education environments. In today’s newer classrooms, more emphasis is being made on having natural light – skylights where possible, and more windows. ALR screens can make a huge difference in these environments. An ALR screen can make a 100” screen fully readable in a conference room with a wall of glass on one side, without spending a fortune on a massively powerful projector. In most situations, ALR screens are the way to go.

In addition to classrooms, ALR screens are ideal for conference rooms, auditoriums, and museums – anywhere where lighting cannot be completely controlled and minimized. They can be a game changer in brighter rooms, requiring far less to be spent on buying a higher power projector.

As more motorized ALR screens hit the market, I would expect this technology to dominate the market. I predict they will be used in most classrooms and conference rooms as the price points will drop, and they won’t cost that much more than a standard screen. If a good ALR screen only adds $500 or so to the budget, but it saves you $1,500 by going with a less bright projector (and still having a better-looking image), they certainly will dominate the business and education world.

ANSI Lumens

The industry standard for measuring brightness is ANSI lumens. When rated brightness is listed in anything but ANSI lumens, it is pretty much a meaningless number especially when trying to compare projectors from different manufacturers (see our article on Lux vs Lumens).

Sometimes manufacturer may rate brightness in other ways like Lux, ISO Lumens, Peak Lumens etc. Since these are not a universal standard of measurement, these proprietary ratings can’t be used to compare brightness between projectors from different manufacturers. It might be helpful when comparing two “LUX” rated models in a manufacturer’s own lineup, but this spec can’t be used to compare brightness with another manufacturer’s projector.

For each projector we review, we measure brightest mode at full wide angle – this is with the iris wide open, so the most amount of light gets through. We take 3-4 readings at about 15-20% out from the center of the lens. That should give a pretty good approximation of ANSI lumens unless a projector’s brightness rolls off excessively at the edges, meaning the image is brighter in the center of the screen

For the rest of the modes, we measure them at mid-zoom, so the iris is closed halfway. This is because it is more common for a projector to be zoomed in a bit than installed at full wide angle.

For some interchangeable lens projectors, max brightness might vary depending on the lens utilized. Once a lens is detected, the projector may adjust its maximum brightness level. For example, below is a chart from Epson for their Pro L1755UNL projector.

Lenses compatible with Epson Pro L1755UNL

 

While brightness is important, it should never be the sole consideration when designing a projection system. There are other factors such as type of screen material, ambient light in the room, and several other factors that may affect the perceived brightness and clarity of the projection image.

Digital Keystone Correction

If a projector is not perpendicularly aligned with the screen “Keystoning” can occur which means the image looks trapezoidal rather than square. Keystone issues are normally corrected by physically moving a projector left, right, up and down or tilting the projector.

 

Needs Vertical Keystone Correction - Projector Reviews - Image
Needs Vertical Keystone Correction

 

Needs Horizontal Keystone Correction - Projector Reviews - Image
Needs Horizontal Keystone Correction

 

If you can physically move a projector, higher-end projectors offer vertical and horizontal lens shifting to solve these alignment issues. Lens shift is the preferred way to correct keystoning because it doesn’t affect resolution.

If a projector does not offer lens shift a user can resort to digital keystone correction to try to properly fit the image on the screen.  While utilizing Digital Keystone Correction reduces resolution, many users are willing to sacrifice a little clarity to ensure that the projected image properly fits their screen.

Some projectors offer both vertical and horizontal adjustment while others may only offer vertical adjustment. Horizonal keystone correction is designed fix issues caused by the projector not being aligned horizontally (left, right) with the screen. Vertical keystone correction is designed to fix issues caused when the projector is place too high or too low to properly align with the screen.

DLP

DLP (Digital Light Processor) works when light passes through a spinning RGB color wheel and then bounces off a single DLP (or DMD, Digital Micromirror Device) chip that is covered with micro-mirrors. The light is reflected off the mirrors on the chip, then passes through the projector’s lens and onto the screen to produce an image. Because DLP projectors only require a single chip, they are often among the smallest and most portable projectors on the market.

 

 

The resolution and performance of DLP chips have improved with each successive generation. Native resolution has increased up to WUXGA (1920 x 1200). While a DLP chip does not have 8.3 million mirrors, it can deliver a perceived resolution of 4K (3840 x 2160).

DLP XPR technology leverages the immense speed of the DMD (Digital Micromirror Device) to process pixels faster than the rate of the video signal. This speed is how DLP can utilize one imaging chip to create multiple colors and multiple pixel locations.

In the earlier DMD designs, the pixel would only pivot on or off using one hinge and axis. The XPR chip tilts in 4 directions and operates fast enough for our eyes to see all the pixels and perceive the entire image all at once.

While the newest 0.47″ DMD chips only have about 2.1 million mirrors, they can deliver a perceived resolution of 8.3 million pixels. This system works so well that it would be difficult for any viewer to see a difference in resolution from a native 4K UHD (8.3 megapixels) imager.

Edge Blending

If you need more light output or want to utilize multiple projectors to display a larger, wider aspect image, many projectors are equipped with several features to make that goal easier.

By utilizing Edge Blending, you can split an image over multiple projectors and display it as one large image while reducing the hard transition from one projector to another. Under the Blend Range menu’s sub-setting, you can fine-tune the blend’s starting position and the width of the blended area. You can use the projector’s Black Level setting to make the difference even less noticeable. The result is an image that looks seamless, like it’s being displayed by a single projector. However, Edge Blending can’t be combined with pixel shifting but that is okay in many situations where maximum flexibility is more important than absolute resolution.

Laser projectors are ideal for edge blending applications.

 

Projectors with laser light engines offer a significant advantage over a bulb-based system in a long-term projector blended installation. If multiple lamp-based projectors are used, not only would the bulbs fail regularly, they will dim at different rates, causing color and brightness shifts. You would need to replace all the bulbs each time one failed to ensure similar characteristics and some additional calibration would probably still be required to produce ideal picture quality.

Filters

Virtually every LCD projector on the market has at least one filter. Since most DLP projectors have a sealed optical assembly, they usually do not. LCD projectors at some point will require a filter change but these days, frequency is about the same as lamp life replacement.

Depending on how many projectors that must be maintained, filter cleaning/replacement could be a logistical and expensive headache. If you have a lot of projectors, frequent filter cleaning can be a labor intensive and expensive chore especially if you are managing 500 projectors spread across 20 schools.

In some cases, the filters are designed to last as long, or even longer, than the projector lamps. We have reviewed some projector models that recommended changing its filters every 12,000 hours. In that timeframe you could have change the bulb 3 times.

HDBaseT and 3G-SDI Support

If you need to run a video signal hundreds of feet, there are two solutions:

  • HDBaseT lets you run HDMI distances of up to 100 meters (about 328 feet) over a low cost CAT5e/CAT6 wire. While the support is built into the projectors, you will need the optional transmitter to implement it. The cost savings of using HDBaseT can be significant which make it a very compelling feature for many installations.
  • 3G-SDI is another great long-distance solution especially for live video. This feature allows the projector to interface directly with a video camera (up to 1080p / WUXGA) located 100 meters away via coax. This is a big feature with big benefits for rental and staging customers, such as Houses of Worship (which are major users of live video and projectors), convention centers, university classrooms, corporate auditoriums and training rooms.

FYI, there are several additional SDI standards including HD-SDI which supports 720p/WXGA content and 6G-SDI which can support up to 4K resolution. Many users of large venue projectors are just fine with HD-SDI support.

HDMI

One of the most common types of video connections is HDMI (High Definition Multimedia Interface). While computers may have multiple video outputs, many newer consumer video devices (streaming boxes, gaming systems, etc.) only include support for HDMI.

There are multiple versions of HDMI Specifications. Each HDMI specification (i.e., HDMI 1.4b) defines support for various video, audio, and networking (Ethernet) signal formats. Each HDMI standard includes a shopping list of different video resolutions and refresh rates and specifies the technical details for how each of these signal formats is to be supported via HDMI.

 

HDMI featuresupport

 

For example, a projector would need to support at least HDMI 1.4a to be compatible with consumer HD video sources like a 3D Blu-ray player or gaming system. Higher HDMI specifications offer several user enhancement features and can also support more bandwidth.

It is the higher data rates between the connected A/V devices that makes video enhancements such as higher resolution and frame rates along with greater color depth possible. HDMI 2.1 specification offers much higher bandwidth capability (up to 48Gbps) than HDMI 2.0b (18Gpbs). This higher bandwidth supports a range of higher video resolutions and refresh rates including 8K@60 and 4K@120, and resolutions up to 10K.

Newer HDMI versions are backward compatible with older standards so you can utilize an older HD Blu-ray player with a newer 4K HDR projector. The chart below outlines content type supported by each HDMI specification:

 

HDMI Certification Video Formats Supported
1.4a HD (Blu-ray, Set Top Box)
1.4b 4K@30fps (SDR)
2.0a 4K@30fps (HDR/SDR)
2.0b 4K@60fps (HDR/SDR)
2.1 4K@120fps / 8K@60fps

 

In addition, HDMI also has different levels of copyright protection called HDCP (High-bandwidth Digital Content Protection). Movie studios continue to demand more and more robust copy protection as the quality of available material increases (HD,4K, HDR, 8K) so the purpose of HDCP is to prevent content copying or playback on an unauthorized device.  For example, payback of copyrighted 4K SDR/HDR content requires support at least HDCP 2.2. In order to playback HDCP-encrypted content, all the devices in the video signal chain (projector, video switcher, A/V receiver, etc.) must be authorized to playback that level of HDCP content.

For more information on the various HDMI standards, check out the various technical blogs we have written in the past.

Links below are to technical blogs by ART and Phil on the subject of HDMI

HDMI 2.1: The Basics. And, Who Needs It Today – A Rant

HDMI 2.0 and Support 4K UHD Video

Beyond HDMI 1.4

HDMI Version (up to HDMI 1.4)

Input Lag

Input lag is an important term in the world of projector gaming. It is a word that relates to the gaming speed performance on projectors – the time between when the gaming system sends out its signal, to the time it is received by the projector, and is measured in milliseconds. The range of acceptable input lag speeds range from as high as 50ms (and a little bit above), to as low as 16ms. The speed of performance on a projector can mean the difference between you beating your opponent or your being beaten.

The Future of Projector Gaming

 

Check out some of our more in-depth reviews and informational article on gaming:

Interchangeable Lenses

High-end and large venue projectors are sometimes sold both with or without a lens. The manufacturers usually offer several optional lenses with different throw ranges to use in specific or specialized situations. This provides the user with far more flexibility than a fixed lens. The same projector can be placed in the front of the room close to the screen using an ultra-short throw lens or way in the back of a large lecture hall using a long throw lens.

Interchangeable Epson Pro Lenses

Laser Based Light Sources

There are several benefits shared by all projectors that use lasers as a light source. First, laser-based light engines turn on within seconds of pressing the power button. There is no time wasted waiting for a lamp to warm up or cool down. Old mercury lamps can be damaged if unplugged before the cooling-down period ends.

Laser-based light engines are incredibly reliable, lasting anywhere from 20k to 30k hours, and are mostly maintenance-free. Chances are, you would need to replace the entire projector long before the laser light engine fails.

Laser light engines are incredibly bright compared to lamps and most LED-based light systems, so they would typically be the best option for projecting on large surfaces. There are typically three types of laser-light engine designs used by today’s projector manufacturers.

 

Laser Phosphor

Most laser projectors utilize the least expensive solution, which is a single blue laser diode array that provides the blue light and excites a yellow phosphor color wheel. Filters are then used to break up the yellow into red and green elements.

For higher brightness, some projectors use a dual blue laser light engine. One blue laser ultimately hits phosphor wheels to generate red and yellow beams, while the other blue laser handles the solely the blue component.

Hybrid Laser Light Engine

For improved color reproduction, another laser light configuration combines a red LED and a blue laser that uses a phosphor chip or a color wheel to generate green light. These hybrid laser projectors out-perform lamp-based projectors in brightness while delivering superior color and long life.

 

Discrete RGB Laser

The best solution is to utilize multiple RGB lasers instead of a phosphor wheel and filters to create clean primary colors. Multi-channel laser light engines tend to produce a wider color gamut, making them a perfect choice for installations that require color accuracy in their displayed content.

In addition to much more accurate colors, because red, green, and blue light is produced by different lasers, a wider color gamut is also possible. Since the RGB laser wavelengths are specifically chosen to optimize the primary colors of red, green, and blue, a RGB laser projector has the ability to reproduce DCI-P3 or even the Rec. 2020 color gamut without the need for a color filter.

Discrete RGB laser light engines are considered to be the best projector light source available, but this performance comes at a price. Laser projectors tend to be physically larger than other types of projectors and are also very expensive. These systems offer the best brightness, so for installations requiring a huge projection screen, this would be the best solution.

Laser Phosphor

There are several benefits shared by all projectors that use lasers as a light source. First, laser-based light engines turn on within seconds of pressing the power button. There is no time wasted waiting for a lamp to warm up or cool down. Old mercury lamps can be damaged if unplugged before the cooling-down period ends.

Laser-based light engines are incredibly reliable, lasting anywhere from 20k to 30k hours, and are mostly maintenance-free. Chances are, you would need to replace the entire projector long before the laser light engine fails.

Laser light engines are incredibly bright compared to lamps and most LED-based light systems, so they would typically be the best option for projecting on large surfaces. There are typically three types of laser-light engine designs used by today’s projector manufacturers.

Most laser projectors utilize the least expensive solution, which is a single blue laser diode array that provides the blue light and excites a yellow phosphor color wheel. Filters are then used to break up the yellow into red and green elements.

For higher brightness, some projectors use a dual blue laser light engine. One blue laser ultimately hits phosphor wheels to generate red and yellow beams, while the other blue laser handles the solely the blue component.

LCD

The technology behind LCD (Transmissive Liquid Crystal Display) starts off with a single light source, just like with DLP. But, with LCD and 3LCD, the single light source is split into 3 beams — one each for red, green, and blue – the primary colors. Once the light is split, mirrors send the beams to different locations inside the projector box. At that point, the light passes through one of the LCD panels (or three panels if it is a 3LCD projector). These panels are not colored but grayscale, and each has a different color filter. The end result, when light passes through them, is the red, green, and blue beams that then pass through a dichroic prism, which recombines the three beams into a single full-color beam.

3LCD projector, unlike most single-chip DLP projectors, can reproduce an equal amount of color lumens as white lumens, which can result in bright richer, looking colors which is beneficial when viewing HDR.

 

The light from a lamp or laser source is split into red and green, and each color passes through a dedicated LCD imaging panel. The light from the three panels is then combined and sent through the lens to the screen.

 

While early LCD projector’s contrast performance was behind its DLP competition, over the years, there have seen remarkable leaps forward for LCD.

A projector is more than the sum of its parts. It has been said that the actual projector is only one-half of the equation, with the screen being the other factor that impacts perceived picture quality. The truth is you have to look at the projector systemically. When you do you will find, among other improvements, the dynamic iris contributes to LCD projector’s improved contrast.

LCoS

With LCoS displays, the process is similar to 3LCD, in that you start by splitting the light into three beams. A key difference, though, is that LCoS (Liquid Crystal on Silicon) is a reflective panel (like DLP) rather than transmissive (light passing through it), like the 3LCD panels. So, light bounces off of the LCoS panels, then to a dichroic prism (like 3LCD) to recombine the light into a single, full-color image.

LCoS imagers have a higher pixel density than their DLP or LCD counterparts so a smaller LCoS chip can produce more resolution. This is why most native 4K Home Theater projectors utilize LCoS chips.

How LCoS Works

 

What this means is about is 8 million pixels, each producing an individual element of the picture. There are other ways of displaying 4K. Technologies like DLP’s wobulation and LCD’s pixel-shifting are some examples. But are these native 4K? It’s something of a debate in the industry. Is native resolution determined by how many pixels you can see on the screen or how many pixels or mirrors exist on the chip? You’re going to have to be the judge of that because it’s about how you perceive the picture.

LED

LED light engines use inorganic LED light-sources in place of a consumable lamp. Like laser light sources, LED light engines are also highly reliable and can offer up to 20,000 hours of use with no maintenance needed resulting in lower-cost operations. LED light sources are mercury-free and can power off and on quickly, even compared to laser light engines.

Using LED as a light source has been growing in popularity, mainly due to their small size, low heat, and affordability. Traditionally LED light engines are found in smaller, more portable projectors like a PICO projector. What PICO projectors lack in Lumens output is more than made up for in their size, power consumption, and portability. In some cases, PICO projectors can fit in a briefcase, purse, or even a pocket.

Although historically LED’s light output was far less than lamp and laser-based projectors, things are changing. Developers of high-output LED lights, like OSRAM, Samsung, and others, have made remarkable strides in increasing the Lumens of the LED light engines. These next generation LED lights can generate up to 3500 lumens of light output.

 

 

BenQ HT9060 LED light engine
How an LED Light Engine Works

 

Starting in 2019, high Lumen, discrete RGB LED light engines are finding their way into projectors. Discrete RGB LEDs create red, green, and blue light. High-speed LED switching takes the place of the color and phosphor-wheels commonly found in DLP projectors to display each color at a frequency impossible to achieve mechanically. Since a wheel is not required, the noise produced is reduced and reliability is increased. RGB LED produces deeper, richer colors than comparable technologies for pure white reproduction and less DLP “rainbowing” (color breakup).

Business and education installations will value the performance and color accuracy of RGB LED-based light engines. These projectors are perfect for classroom and conference room type environments able to produce laser competitive colors, reliability, and, with the exception of brightness, do it at a lower price.

Just like laser light engines, LED light engines can and do have alternate configurations just as listed in hybrid laser light engines.

Lens Shift

When a projector is properly aligned with the screen the image will be “perfectly” rectangular. We all have been in rooms where the image was much wider at the top than the bottom, that trapezoidal shape is usually referred to as Keystoning.

Let’s start with why that happens. A projector typically sits on a table so that its lens is about even (or slightly below) the bottom of the screen. Since the distance to the top left and right corners of the screen is farther from the lens than the bottom left and right corners, the image spreads out more. The result: a wide image at the top and a narrow image at the bottom.

If you can’t move the projector, lens shift is the preferred way to correct keystoning issues because unlike electronic keystone correction, it doesn’t affect resolution. Lens shifting moves the lens itself up and down and left and right within the projector’s chassis to align the projected image to the screen. A projector may offer both horizontal and vertical lens shift but the amount of overall adjustment can vary by projector type due to various internal layouts of projectors. Normally 3LCD projectors have a larger range of available lens shift than a comparable DLP model. Also, the amount of vertical adjustments applied affect the amount of horizontal adjustment available.

Variable Lens Shift is the best way to keep your image rectangular unless you can place the projector right where it needs to be. For more information on Lens Shift check out the technical blog we wrote  a few years ago.

Monitoring and Control

At a school or university there could be dozens or possibly hundreds of projectors scattered around the campus so the ability to quickly check remotely that each projector is performing satisfactorily is important. There may also be times where you may want to control multiple projectors simultaneously without reaching for the factory remote control.

 

 

MONITORING AND CONTROL VIA A NETWORK

Once you have connected a compatible projector to your network, you can control it using a web browser. This allows you to access the projector remotely and control things like focus, zoom, shift, and test patterns. You can even set up a networked projector to send you an e-mail alert if there is a problem. The email will list the name of the projector experiencing a problem and detailed information about the issue. In addition to being able to control a projector via a web browser, some manufacturers offer software program options which can be used to monitor and control the projector.

 

Some Projector Management software allows you to check the status of multiple networked projectors and perform various projector operations from your computer. You can monitor the status of multiple projectors and get information such as such as power status, errors, and warnings so you are alerted to projector abnormalities immediately. You can also select individual projectors or projector groups to check detailed information such as the usage hours of the projector light source, the current input source and any current errors or warnings. This software is more focused on monitoring.

Projector Professional Tools offer further flexibility by allowing you to adjust and control images projected from networked projectors using a computer. You can focus, shift, zoom, apply Geometric Correction, fine tune Edge Blending and much more on multiple projectors without having to reach for a remote control. This software option is more focused on control.

It can be downloaded from a manufacturer’s support site. Previous testing has proven that these programs work well and provide lots of controls, including the list below:

  • Remote access and control through a network
  • Remote monitoring of literally hundreds pf networked projectors
  • View status – including input sources, power on/off, lamp life hours and more
  • Email notification (SMTP) to send alerts to your handheld device or computer
  • Preventative maintenance features including temperature levels and error alerts
  • Pre-schedule timers to alert filter and lamp replacement needs
  • Enterprise SNMP plug-in available

 

3RD PARTY CONTROL

In addition to control software offered by the manufacturer, many business/installation and education class projectors are also compatible with 3rd party control systems such as the Crestron RoomView network monitoring and control system, which also allows you to setup and adjust a networked projector.

 

DMX ART-NET

DMX is an older command and control system that is best known for controlling lighting. DMX is still used heavily today for stage work and in classrooms. It is still a viable solution for theaters putting on live shows and concerts.

With DMX Art-Net, projectors can be controlled/automated along with the rest of the lighting which can be a powerful way to tackle things like projection mapping (which is utilized in many concerts these days).

Projection Mapping

Projection mapping is masking the image digitally to light up non-traditional, often three-dimensional objects. This is used often at concerts, museums, and other digital signage applications. While there are powerful software-based projector mapping solutions, some projectors have a Geometric Correction feature which lets you correct image distortion caused by projecting an image onto a curved or right-angled screen. You cannot combine traditional H/V keystone correction with the other image shape correction methods with projection mapping.

Large 3D projection mapped image from 16 Panasonic Laser Projectors.

Projector Bulbs

Depending on usage, a projector’s bulb will have to be replaced after several thousand hours. Although the brightness is reduced, running a projector in its ECO mode can increase the projector’s lamp life by up to 60%.

ELPLP97 Replacement Projector Lamp / Bulb
Replacement Projector Lamp / Bulb

 

If the projector is going to be mounted, try to avoid selecting a projector that must be taken down from the mount to change the lamp. For example, don’t choose a projector with the lamp access door on the bottom where the projector attaches to the mount. Removing the projector to make for a lamp replacement takes a whole lot longer and increases maintenance cost.

Fortunately, most projector’s lamp doors are located on the top or side of the unit. This allows fast lamp replacements, if a projector is already cool, it shouldn’t take more than 20 minutes. If you have to unmount the projector from the ceiling or wall mount, you probably need to add, at a minimum, an additional 20-30 minutes of service time

Resolution Related Terms

Resolution is a term that refers to the number of horizontal and vertical pixels of the projected image. The higher the number of pixels, the higher the resolution, and the sharper the image.

Common resolutions found on projectors:

Type Resolution Aspect Ratio
SVGA* 800 x 600 4:3
WVGA* 853 x 480 16:9
XGA 1024 x 768 4:3
WXGA 1280 x 800 16:10
WUXGA 1920 x 1200 16:10
720p 1280 x 720 16:9
1080p 1920 x 1080 16:9
4K UHD 3840 x 2160 16:9

 

* SVGA and WVGA are essentially “legacy” resolutions.

While there are still some very low cost projectors sold with SVGA an WVGA resolutions (including some “toy” priced dim LED pico projectors for home), but they are no longer normally bought by schools. There are still large numbers of them in K-12 schools. Most are long overdue for replacement. Their bulbs last only a fraction of the life of new projectors (nevermind laser projectors), so the cost of supporting those old projectors is high.

XGA models are typically used to replace the SVGA (and if any are still around – VGA) projectors. SVGA projectors are typically replaced by WXGA, WUXGA or 1080p projectors.

HD VS PIXEL SHIFTING VS NATIVE 4K

Most pixel shifting projectors can accept up to a 4K signal. While pixel shifting can’t match the resolution of a true 4K projector, it does increase sharpness and detail compared to a standard 2K projector. When fed 4K content, the projector uses pixel shifting to fine tune the image to more closely resemble 4K. Pixel shifting fires each pixel twice by shifting the location by 1/2 pixel diagonally. Combined with good image processing, pixel shifting can do a very nice job emulating the original 4K content.

The images above show the noticeable improvement pixel shifting provides when viewing 2K and 4K content. The images above are screenshots of projected 4K material. The first images are close ups showing the same image with Pixel Shifting Off and On. They really highlight how much this feature increases the clarity and detail of a WUXGA projector.

When viewed in person, the actual differences on the screen are greater than what you are seeing on this site. This is because of the heavy compression and scaling of the images for the web, so the differences you are seeing when viewing it on this website will be less noticeable. As you can see in the above images, when you compare 4K content with pixel shifting turned on and off, the difference is impressive.

Small type and fine details that can’t be discerned on a basic 2K – WUXGA (or 1,080p) projector can often be resolved with pixel shifting. It is enough to make a real readability difference on CAD, engineering, and scientific drawings, renderings, or anything else demanding max detail.

It is only when you do a side-by-side comparison between a true 4K projector versus a 2K pixel shifting projector that the resolution difference is noticeable. The images below show the visible resolution difference between a native 4K projector and a projector utilizing pixel shifting when displaying native 4K content.

 

4K Content shown on a pixel shifting Projector
4K Content shown on a native 4K Projector

 

Since the projector’s native resolution is approximately 2.3 MP, it won’t be as sharp/detailed as a true 4K projector (8,8 MP resolution). While a Pixel Shifting HD projector does deliver more clarity, it still can’t match the resolution provided by a native 4K projector.

Pixel Shifting also requires a lot of processing so it can’t be combined with some features like edge blending and Creative Frame Interpolation  but even some more basic things, including some types of noise reduction cannot be utilized.

So how do I choose between a pixel-shifting projector and a true 4K projector? To make a wise decision you must factor in your budget, what you are watching, and from where you are watching it.

 

 

True 4K high lumens projectors cost at least four to five times as much as their 2K counterparts. Consider this, an 8,000 lumen true 4K laser projector can retail for $60,000 while an Epson pixel shifting 16,000 lumen 2K laser projector costs about 1/3 of that amount. This will be true until we see dramatic price drops in the true native 4K projectors to make them more price competitive. True 4K projectors are going to be hard to justify in most situations even when 4K content will be used.

In many situations, the content lacks the detail required and is viewed at a distance where the difference between 4K and pixel shifting cannot be perceived. While pixel shifting can’t match the resolution of a true 4K projector, it does increase sharpness and detail compared to a standard 2K projector.

So, if the image is going to be viewed from fairly far away, a brighter, less expensive pixel shifting projector might be a better option. In many situations the benefit of extra brightness far exceeds the benefits of additional resolution.

EQUIVALENT VISIBILITY RULE

The Equivalent Visibility Rule is used to determine how large a display size is needed when teaching or “presenting” to a group, regardless of the number of those attending the class or meeting. It is more effective today than the old 4/6/8 rule long used for determining how large a projection screen or monitor is needed, in a room.

Background: No longer do we primarily present to the classroom or conference room with presentation software such as PowerPoint. Or, rather we still do, however, today we are also electronically displaying emails, websites, spreadsheets, documents, engineering drawings, art work, and much more.

4/6/8 (without getting into it) is an old “A/V” rule that was good for figuring out if the person in the back of the room can follow a presentation using typical large type (30, 36, 48, and 60 point). But, it doesn’t work well when you need that person to be able to read the numbers on a spreadsheet.

Essentially, the Equivalent Visibility Rule answers this problem.  Given that people work with spreadsheets, docs, detailed drawings, etc. normally their desks, and can read all that content without trouble, then if those people typically have about a 21” monitor on their desk and sit about 28” back, how large a display would be needed for a person sitting 10 or 12, or 30 feet from the display?

You may be surprised.  If the person furthest back in the room is 15 feet from the screen or display, then to read all that small type – the screen should be (drumroll…) at least 100” diagonal. And ideally between 120” and 150”.

 

RGB Laser

There are several benefits shared by all projectors that use lasers as a light source. First, laser-based light engines turn on within seconds of pressing the power button. There is no time wasted waiting for a lamp to warm up or cool down. Old mercury lamps can be damaged if unplugged before the cooling-down period ends.

Laser-based light engines are incredibly reliable, lasting anywhere from 20k to 30k hours, and are mostly maintenance-free. Chances are, you would need to replace the entire projector long before the laser light engine fails.

Laser light engines are incredibly bright compared to lamps and most LED-based light systems, so they would typically be the best option for projecting on large surfaces. There are typically three types of laser-light engine designs used by today’s projector manufacturers.

 

How RGB Lasers Work

 

The best solution is to utilize multiple RGB lasers instead of a phosphor wheel and filters to create clean primary colors. Multi-channel laser light engines tend to produce a wider color gamut, making them a perfect choice for installations that require color accuracy in their displayed content.

In addition to much more accurate colors, because red, green, and blue light is produced by different lasers, a wider color gamut is also possible. Since the RGB laser wavelengths are specifically chosen to optimize the primary colors of red, green, and blue, a RGB laser projector has the ability to reproduce DCI-P3 or even the Rec. 2020 color gamut without the need for a color filter.

Discrete RGB laser light engines are considered to be the best projector light source available, but this performance comes at a price. Laser projectors tend to be physically larger than other types of projectors and are also very expensive. These systems offer the best brightness, so for installations requiring a huge projection screen, this would be the best solution

Short Throw Projectors

Short throw projectors by comparison mount less than half the distance back.  For screen sizes of 100” or smaller, they can usually be mounted on a telescoping arm, on a wall mount placed only inches above the screen, but telescoping to 40 or more inches.

Thanks to the telescoping mounts, these short throw projectors mount directly above the screen which makes wiring is a breeze by comparison to standard throw projectors.  Limitations include maximum screen size.  100” screens are about as large many short throw projectors can handle from those mounts.

 

Standard Throw Projectors

Standard throw projectors overall, are the majority of the market, and, on a feature for feature basis, brighter and offer more per dollar invested.

 

Epson L400U Ceiling Mount and Cord Cover

 

As they are typically ceiling mounted in class rooms and conference rooms, they have the disadvantage of being mounted on a different surface from the screen. Many schools and businesses have drop ceilings which does help simplify the installation Ceiling mounting typically makes for a more expensive installation and can be a bit more difficult to maintain.