4K Video Projectors Explained

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

Since its introduction in 2012, the success of 4K Ultra HD TV is undeniable. In contrast to 3DTV, consumers jumped on the 4K bandwagon because of its increased resolutionHDR, and wide color gamut. All have elevated the TV viewing experience.

Epson 4Ke Video Projector/Home Theater Lifestyle

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

It's All About the Pixels

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.

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

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 1,920 pixels across the screen horizontally (per row) and 1,080 pixels up and down the screen vertically (per column). To determine the number of pixels covering the screen surface, 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).

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

In other words, the needed number of pixels must be smaller to fit into a chip with a rectangular surface that may only be about 1-inch square. It requires more precise production and quality control, increasing the cost for the manufacturer and consumer.

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

The Shifty Approach: Cutting Costs

Since squeezing all the pixels needed for 4K on smaller chips is expensive, JVC, Epson, and Texas Instruments have an alternative that 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.

Illustration of How Pixel Shift Technology Works

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 these two approaches work.

Instead of starting with an expensive chip that contains all 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 projectors are 1080p video projectors.

Epson 4KE Pixel Shift Process

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 rapidly shifts each pixel diagonally back-and-forth by a half-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.

Since the pixel shift is only half a pixel, the visual result may be more like 4K than 1080p, even though, technically, there aren't many pixels displayed on the screen. Epson and JVC's pixel shifting process 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 get a detail boost over a standard 1080p projector.

When Pixel Shift technology is activated, it doesn't 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 is in 1080p.

The Texas Instruments Approach for DLP Projectors

Epson and JVC employ LCD technology. 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. 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. This results in the appearance of a more accurate 4K-like image.
  • Instead of using a 1080p DLP chip, Texas Instruments offers another chip. It starts with 2716 x 1528 (4.15 million) pixels (twice the number that the Epson and JVC chips begin with). It 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 2716 x 1528 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 eShift and Epson 4Ke projectors display. This system isn't the same as Sony's 4K, in that it doesn't start with 8.3 million physical pixels. However, it comes visually the closest, at a cost comparable to the system used by Epson and JVC.

Like Epson and JVC systems, incoming video signals are either upscaled or processed accordingly. 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 Real 4K Approach: Sony Goes It Alone

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, Sony has gone with real 4K and has been vocal about it.

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

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

The pixel count on the Sony 4K chips is 8.8 million pixels (4096 x 2160), the same standard used in commercial cinema 4K. All consumer-based 4K content (such as Ultra HD Blu-ray) gets a slight boost to that extra 500,000-pixel count.

However, Sony doesn't 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 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 the Sony 4K projectors are expensive, with starting prices of about $5,000. When you add the price of a suitable screen, the solution becomes more costly than buying a large screen 4K Ultra HD TV. However, if you're looking for an 85-inch or larger picture and want true 4K, the Sony approach is a desirable option.

The Bottom Line

It boils down to 4K resolution, except for Sony's method, which is implemented differently on most video projectors than it is on a TV. Although it isn't necessary to know the technical details when shopping for a 4K video projector, 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 real 4K. You'll hear the terms 4K, Faux-K, Pseudo 4K, and 4K Lite tossed around as you read video projector reviews and shop at your local dealer.

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

In most cases, it's difficult to tell the difference between each approach unless you get close to the screen or view a side-by-side comparison of each type of projector calibrated for other factors (for example, color, contrast, and light output).

Real 4K may look slightly sharper depending on the screen size (check screens 120 inches and up) and the seating distance from the screen. However, your eyes can only resolve so much detail, especially with moving images. Plus, there are variations depending on your visual abilities. There isn't a fixed screen size or viewing distance that produces the same perception difference.

With the cost difference between real 4K (where prices start at about $5,000) and pixel shifting (where prices start at less than $2,000), the cost is something to consider, especially if you find that the visual experience is comparable.

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

Perform your own observations to determine which solution looks best to you and which brand and model fits your budget. The final step is to set it up.

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