4K Eshift3 is the name for JVC's detail and sharpness enhancement system. What makes it different than the competition's is that it's both mechanical as well as digital. These JVC projectors basically produce the usual 108p output - 1920x1080, but then the projector physically shifts the pixels up to the right I believe, by 1/3 of a pixel, and projects again. This allows them to in some cases blend colors better, and provide more smoothness.
But when it comes to producing very fine detail it still comes back to the size of the pixels. They are the same size as any other 1080p projector. In addition to the physical, JVC will upscale 1080 content essentially to 4K trying to figure out what's missing, and then calculate the best mapping for the original and shifted.
It works very nicely, you can get a rather visible amount of perceived detail and sharpening, before any artifacts become an issue. Elsewhere in this review you can see how the DLA-RS4910 or RS49 or X500R compares with a true 4K projector, in this case Sony's $15,000 VW600ES. I've got a couple of comparison photos using 1080p content, and a couple with 4K content: 3840x2160. For your consideration, we previously created a video demonstrating last year's 4K Eshift2, showing the change from settings varying from shift off, to shift with a moderately high setting.
Short version - a very good detail enhancement solution. I'd put it second behind Sony's Reality Creation but both have strengths. The ability this year to input 4K is an important improvement for JVC, but please don't expect this to look like a true 4K projector when fed true 4K content. I wish JVC would drop the "4K" from the name. That's my biggest beef, but at least it will accept at least some forthcoming 4K content.
In the images in this player, the first three are 1080p with the 2nd and 3rd ones already heavily cropped. Remember even enlarged these images are only 1000 pixels wide, so won't be a sharp as "real life."
The next two images are from true 4K content, while the second sunset, is also 4K, but is an image from the 4K Sony VW600ES, for your comparison. The final two images of Leeloo from the 5th Element show the settings changes to E-Shift3, from 25 to 60, but note that there's exactly no difference in the images. This is apparently the bug JVC mentioned that they are working on a fix for.
I wanted to crank up the Enhance slider to 60 from the default (25), to see how much more "detail" it produced. Unfortunately, as you can see in the for While high contrast areas (tree vs sky) are very close to the Sony, look at individual clouds where the shifts are subtle and the Sony provides more detail. Hey, the Sony's almost 3x the price, all's fair. Other comparison later.
Last four images demonstrate eshift feature. First image in each pair is at 50, second image in each pair is at 25.