4K Video Projectors Explained

Epson 4Ke Video Projector/Home Theater Lifestyle Image
Epson 4Ke Video Projector/Home Theater Lifestyle Image. Image provided by Epson
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The Truth About 4K Video Projectors

JVC DLA-RS520 e-Shift 4 (top) - Epson Home Cinema 5040 4Ke (bottom) Projectors
JVC DLA-RS520 e-Shift 4 (top) - Epson Home Cinema 5040 4Ke (bottom) Projectors. Images provided by JVC and Epson

Since their introduction in 2012, the success of 4K Ultra HD TVs is undeniable. Contrasting from the debacle that was 3DTV, consumers have jumped on the 4K bandwagon thanks to its increased resolutionHDR, and wide color gamut. All which have definitely elevated the TV viewing experience.

While Ultra HD TVs are flying off store shelves, the vast majority of home theater video projectors available are still 1080p rather than 4K. What's the main reason? Sure, incorporating 4K into a video projector is lot more expensive than it is with a TV, but that's not the whole story.

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It's All About the Pixels

Illustration of What LCD TV Pixels Look Like
Illustration of What LCD TV Pixels Look Like. Image via Wikimedia Commons - Public Domain

Before plunging into how 4K is implemented in TVs vs video projectors, we need to have a reference point to work from. That point is the pixel.

A pixel is defined as a picture element. Each pixel contains red, green, and blue color information (referred to as sub-pixels). In order to create a full image on a TV or video projection screen a large number of pixels is required. The number or pixels that can be displayed determines the screen resolution.

How 4K Is Implemented In TVs

In TVs, there is a large screen surface in which to "pack in" the number of pixels required to display a specific resolution.

Regardless of the actual screen size for 1080p TVs, there are always 1,920 pixels running across the screen horizontally (per row) and 1,080 pixels running up and down the screen vertically (per column). To determine the total number of pixels covering the entire screen surface, you multiply the number of horizontal pixels with the number of vertical pixels. For 1080p TVs that totals about 2.1 million pixels. For 4K Ultra HD TVs, there are 3,480 horizontal pixels and 2,160 vertical pixels, resulting in a total of 8.3 million pixels filling the screen.

That is definitely a lot of pixels, but with TV screen sizes of 40, 55, 65, or 75 inches, manufacturers have a large area (relatively speaking) to work with.

However, for DLP and LCD video projectors, although images are projected on a large screen - they have to pass-through or reflect off chips inside the projector that are much smaller than a LCD or OLED TV panel.

In other words, the needed number of pixels have to be smaller in order to be crammed into a chip with a rectangular surface that may only be about 1-inch square. This definitely requires much more precise production and quality control that greatly increases the cost for the manufacturer and the consumer.

As a result, the implementation of 4K resolution in video projectors is not as straightforward as it is in a TV.

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The Shifty Approach: Cutting Costs

Illustration of How Pixel Shift Technology Works
Illustration of How Pixel Shift Technology Works. Image provded by Epson

Since squeezing all the pixels needed for 4K on small chip(s) is expensive, JVC, Epson, and Texas Instruments have come up with an alternative that they claim yields the same visual result at lower cost. Their method is referred to as Pixel Shifting. JVC refers to their system as eShift, Epson refers to theirs as 4K Enhancement (4Ke), and Texas Instruments refers to theirs informally as TI UHD.

The Epson and JVC Approach for LCD Projectors

Although there are slight differences between the Epson and JVC systems, here are the essentials of how their two approaches work.

Instead of starting with an expensive chip that contains all the 8.3 million pixels, Epson and JVC start with standard 1080p (2.1 million pixels) chips. In other words, at their core, the Epson and JVC's are still 1080p video projectors.

With the eShift or 4Ke system activated, when a 4K video input signal is detected (such as from Ultra HD Blu-ray and select streaming services), it is split into 2 1080p images (each with half of the 4K image information).  The projector then rapidly shifts each pixel diagonally back-and-forth by a half-a-pixel width and projects the result onto the screen. The shifting motion is so fast, it fools the viewer into perceiving the result as approximating the look of a 4K resolution image.

However, since the pixel shift is only half a pixel, although the visual result may be more like 4K than 1080p, technically, there aren't that many pixels displayed on the screen. In fact, the pixel shifting process implemented by Epson and JVC only results in the display of about 4.1 million "visual" pixels, or twice the number as 1080p.

For 1080p and lower resolution content sources, in both the Epson and JVC systems, pixel shifting technology upscales the image (in other words, your DVD and Blu-ray Disc collection will get a detail boost over a standard 1080p projector).

It must also be pointed out that when Pixel Shift technology is activated, it does not work for 3D viewing. If an incoming 3D signal is detected or Motion Interpolation is activated, eShift or 4K Enhancement is automatically turned off, and the displayed image will be 1080p.

Examples of Epson 4Ke Projectors.

Examples of JVC eShift Projectors.

The Texas Instruments Approach For DLP Projectors

Epson and JVC are projector platforms that employ LCD technology, but a variation on pixel shifting has been developed for the Texas Instruments DLP projector platform.

Instead of using a 1080p DLP chip, Texas Instruments is offering up a chip that starts with 2716x1528 (4.15 million) pixels (which which is twice the number that the Epson and JVC chips start with).

What this means is that when the Pixel Shift process and additional video processing is implemented in a projector using the TI system, instead of about 4 million pixels, the projector sends out 8.3 million "visual" pixels to the screen - twice as many as the JVC's eShift and Epson's 4Ke. Although this system is not the exactly same as Sony's Native 4K, in that it doesn't start with 8.3 million physical pixels, it comes visually the closest, at a cost comparable to the system used by Epson and JVC.

Just as with Epson and JVC systems, incoming video signals are either upscaled or processed accordingly and, when viewing 3D content, the Pixel Shifting process is disabled.

Optoma is the first to implement the TI UHD system, to be followed by Acer, Benq, SIM2, Casio, and Vivitek (stay tuned for updates).

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The Native Approach: Sony Goes It Alone

Sony VPL-VW365ES Native 4K Video Projector
Sony VPL-VW365ES Native 4K Video Projector. Images provided by Sony

Sony has a tendency to go its own way (remember BETAMAX, miniDisc, SACD, and DAT audio cassettes?) and they are also doing so in 4K video projection. Instead of the more cost effective Pixel shifting approach, from the beginning Sony has gone "Native 4K", and has been very vocal about it.

What the native approach means that all of the necessary pixels needed to project a 4K resolution image are incorporated into a chip (or actually three chips - one for each primary color).

It is also important to note that the pixel count on Sony's 4K chips is actually 8.8 million pixels (4096 x 2160), which is the same standard used in commercial cinema 4K. This means that all consumer based 4K content (Ultra HD Blu-ray, etc...) gets a slight boost to that extra 500,000 pixel count.

However, Sony does not use pixel shifting techniques to project 4K-like images onto a screen. Also, 1080p (including 3D) and lower resolution sources are upscaled to "4K-like" image quality.

The advantage of Sony's approach, of course, is that the consumer is buying a video projector in which the number of actual physical pixels is actually slightly more than on a 4K Ultra HD TV.

The disadvantage of Sony's 4K projectors is that there are very expensive, with starting prices of about $8,000 (as of 2017). Add the price of a suitable screen, and that solution becomes much more expensive than buying a large screen 4K Ultra HD TV - but if you are looking a picture 85-inches or larger, and want to make sure you get true 4K, the Sony approach is certainly a desirable option.

Examples of Sony 4K Video Projectors

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The Bottom Line

1080p vs Pixel Shifted 4K
1080p vs Pixel Shifted 4K. Image provded by Epson

What all of the above boils down to is that 4K resolution, with the exception of native method used by Sony, is implemented differently on most video projectors than it is on a TV. As a result, although it isn't necessary to know all of the technical details, when shopping for a "4K" video projector, consumers do need to be aware of labels such as Native, e-Shift, 4K Enhancement (4Ke), and the TI DLP UHD system.

There is a continuing debate, with advocates on both sides, regarding the merits of pixel shifting as a substitute for native 4K - you will hear the terms "4K" "Faux-K", "Pseudo 4K", "4K Lite", tossed around as you peruse video projector reviews and shop at your local dealer.

Having seen projected images using each of the above options over the years from Sony, Epson, JVC, and recently Optoma, in most cases it is actually hard to tell the difference between each approach, unless you get very close to the screen, are viewing in a controlled testing environment in which you are viewing a side-by-side comparison of each type of projector that are also calibrated for other factors (color, contrast, light output).

Native 4K may look slightly "sharper" depending on screen size (check screens 120 inches and up), and actual seating distance from the screen - However, to put it simply, your eyes can only resolve so much detail - especially with moving images. Add the fact that there are variations in how well each of us see, there is no fixed screen size or viewing distance that will necessarily produce the same perception difference for each viewer.

With the cost difference between native (where prices start at about $8,000) and pixel shifting (where prices start at less than $3,000), that is also definitely something to consider, especially if you find that the visual experience is comparable.

In addition, keep in mind that resolution, although important, is just one factor in obtaining great image quality - also take light source method, light output, and color brightness into consideration, and don't forget to factor in the need for a good screen.

It is important to perform your own observations to determine which solution looks best to you, and which specific brand/model fits your budget.