4K Video Projectors Explained

Implementing 4K in video projectors is not the same as on TVs

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

Epson 4Ke Video Projector/Home Theater Lifestyle Image
Image provided by Epson

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

It's All About the Pixels

Illustration of What LCD TV Pixels Look Like
Wikimedia Commons / Public Domain

Before plunging into how manufacturers implement 4K in TVs vs. video projectors, we need a reference. That point is the pixel.

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

How 4K Is Implemented in TVs

TVs have a large screen surface 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 about 8 million pixels filling the screen.

That is a lot of pixels, but with TV screen sizes of 40, 55, 65, 75, or 80 inches, manufacturers have a large area (relatively speaking).

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

In other words, the needed number of pixels have to be smaller to cram into a chip with a rectangular surface that may only be about 1-inch square. It requires much more precise production and quality control that significantly increases the manufacturer and consumer costs.

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

The Shifty Approach: Cutting Costs

Illustration of How Pixel Shift Technology Works
Epson

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

The Epson and JVC Approach for LCD Projectors

Epson 4KE Pixel Shift Process
Epson

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 two 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 fast, fooling 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 many pixels displayed on the screen. Epson and JVC's pixel shifting process 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).

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 turns off automatically, and the displayed image will be 1080p.

The Texas Instruments Approach for DLP Projectors

Epson and JVC employ LCD technology, but Texas Instruments developed a pixel shift variation for its DLP projector platform.

Texas Instruments 4K Pixel Shifting Tech
Texas Instruments and BenQ

Texas Instruments offers two options for a 4K-like display.

  • One option employs a 1080p resolution DLP chip similar to what Epson and JVC start with. Still, instead of shifting the pixels rapidly back and forth once to achieve a 4K-like result, in the same period, the pixels are shifted twice, both horizontally and vertically, which results in the appearance of a more accurate 4K-like image.
  • Instead of using a 1080p DLP chip, Texas Instruments offers another chip that starts with 2716x1528 (4.15 million) pixels (twice the number that the Epson and JVC chips begin with) and then shifts the pixels diagonally in a similar fashion as Epson and JVC do.

When the Pixel Shift process and additional video processing are implemented in a projector using the TI system using either their 1080p or 2716x1528 chip, instead of about 4 million pixels, the projector sends out 8.3 million pixels to the screen.

This is twice as many pixels as the JVC's eShift and Epson's 4Ke projectors can display. Although this system is not the 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 was the first to implement the TI UHD system, followed by Acer, Benq, SIM2, Casio, and Vivitek.

The Native Approach: Sony Goes It Alone

Sony VPL-VW295ES IMAX Enhanced 4K Video Projector
Sony Electronics

Sony tends 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.

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

It is also important to note that the pixel count on Sony's 4K chips is 8.8 million pixels (4096 x 2160), which is the same standard used in commercial cinema 4K. 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 upscale 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 slightly more than on a 4K Ultra HD TV.

The disadvantage is that Sony's 4K projectors are very expensive, with starting prices of about $5,000. Add the price of a suitable screen. The solution becomes much more costly than buying a large screen 4K Ultra HD TV — but if you are looking for a picture 85-inches or larger and want to make sure you get true 4K, the Sony approach is undoubtedly a desirable option.

The Bottom Line

Sony VPL-VW365ES Native 4K (top) - Epson Home Cinema 5040 4Ke (bottom) Projectors
Sony and Epson

All of the above boils down to that 4K resolution, except for Sony's native method, which 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.

In most cases, it is difficult to tell the difference between each approach unless you get very close to the screen or view a side-by-side comparison of each type of projector 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 sees. There is no fixed screen size or viewing distance that will necessarily produce the same perception difference.

With the cost difference between native (where prices start at about $5,000) and pixel shifting (where prices start at less than $2,000), that is also definitely something to consider, especially if you find that the visual experience is comparable.

Keep in mind that resolution, although important, is just one factor in obtaining excellent image quality. Also, consider the light source methodlight output, and color brightness, and the need for a good screen.

It is essential to perform your own observations to determine which solution looks best to you, and which specific brand/model fits your budget. The final step is to set it all up.