Faux-K vs 4K Projectors – A Look At True 4K, 4K UHD and 1080p Pixel Shifters

Faux-K:  What is it?  First, some writers  started referring to projectors that could accept 4K content, but didn’t have 8 million discreet pixels to show it, as FauxK.  I joined that party.  I wish I had invented the term, but I commend whomever did.  I found an early thread, on one of the forums, from back in 2011 with a reviewer “debating” what he felt was a 1080 pixel shifting projector line might be misconstrued at true 4K.  For those curious there’s a link below.

VPL-VZ1000ES_4K-HDR_deepwater-horizon_rig

4K content from The DeepWater Horizon, projected by Sony’s ultra short throw true 4K projector – 8.3 megapixels no overlapping pixels.

I consider any projector that can put at least 3840×2160 discreet pixels on the screen – without any overlap, to be “true 4K”  (not an official term).

Let’s start with the simple truth that Faux-K isn’t any official term that some standard committee’s blessed.  Consider it slang.The term has been showing up projector industry since at least 2011.

Here’s the thing:  Traditionally we measured resolution (still do), by the number of discreet pixels horizontally and vertically, such as 1080p being 1920×1080 pixels, that’s roughly 2 megapixels.  But, when pixel shifting showed up first in projectors by JVC, and shortly after by Epson, we ended up with a 1080p projector capable of hitting the screen with 4 million pixels, but it required overlapping those pixels.  They didn’t create smaller pixels so they could get more on the screen, they just fired them twice, but shifting by a half pixel.  There’s real advantages to that, but there is one truth, that holds for all pixel shifting projectors.

They cannot produce as sharp an image as a projector with the same number of pixels hitting the screen, when the other projector has discreet pixels – each one is separate, no overlap.  Technically, it’s no contest!  It’s this simple:

The area of each 4K (3840×2160) pixel on, say a 100″ screen, is exactly one fourth the area of of a 1080p projector’s pixel,  whether that 1080p projector is a pixel shifter or not.  Those projectors simply cannot be a sharp (unless there are serious problems with the 4K projector.  The true 4K projector can do a perfect vertical or horizontal line, that’s 1/3840 of the screen width.  for a pixel shifter that’s 1080p, that line has to be at minimum twice as thick as a true 4K line.  Got it?

Epson-LS10500_4K-HDR_ghostbusters_manhattan

CGI enhanced image of lower Manhattan, projected by Epson LS10500 1920×1080 with pixel shifting, from 4K Ghostbusters.

 

Now welcome to the world of DLP – TI (Texas Instruments) created a new DLP chip, neither true 1080p, nor true 4K (we’re going to stick to consumer 4K – technically true 4K would be 4096 pixels  (movie theaters) not 3840.

This DLP chip has 2716×1528 discreet pixels, not 3840×2160.  Multiply that out, you get 4.15 megapixels and by using pixel shifting they get 8.3.  That 4.15 megapixels is double the standard 1080p projector and the same as a pixel shifting 1080p projector.

HT8050_ghostbusters-4K_manhattan

CGI enhanced image of lower Manhattan, projected by the BenQ HT8050 4K UHD projector with 2716×1528 native resolution plus pixel shifting, from 4K Ghostbusters.

 

Well folks, that makes them 4K UHD, not true 4K, by my take.  What is 4K UHD, its a resolution used by Blu-ray UHD players and YouTube for example (UHD = Ultra High Definition).  That is, it’s part marketing, part reality.

To test maximum resolution, I’m creating a 3840×2160 image in photoshop of vertical lines, all one pixel wide, I’ll change colors as frequently as from one pixel to the next.  Something like R,G,B,R,G,B and then others such as:  R,G,B,C,Y,M, RRGBB, GGYBB, and wider ones, perhaps R,R,B,B,G,G…  Only the true 4K projector will be able to see all those colors.

VPL-VZ1000ES_4K-HDR_ghostbusters_manhattan

CGI enhanced image of lower Manhattan, projected by the Sony VZ1000ES true 4K projector with 3840×2160 native resolution plus pixel shifting, from 4K Ghostbusters.

Click on, and zoom in as close as you can, say to the area around the tallest tower, and look closely at the lighting, the LS10500 1080p pixel shifter is a little soft – less detailed than the BenQ HT8050 the 4K UHD projector, which in turn is not as detailed and defined as the $25K Sony VPL-VZ1000ES immediately above.  The differences aren’t huge, but they make a visible difference.

I say that using this logic:  If that’s real 4K, then so would be “4K UHD” projector based on a standard HD – 720p – of 1280×720 (you know, that’s the lower HD resolution, the one ESPN and ABC still broadcasts at).  Using pixel shifting a company could start with that native resolution and shift pixels 9 times and you are back at 8.3 megapixels.  Of course each of those individual pixels would be about the size of a bowling ball compared to a baseball (for true 4K), or maybe a baseball compared to a golf ball.

Hey, I didn’t do the math on those, call them guesses.  After all, each of those pixels would be 9 times the size of one true 4K pixel.  Good luck getting fine detail out of that, but I believe it would still technically be 4K UHD.  (I haven’t read the specs for 4K UHD beyond the 8 megapixel requirement, and the various relationships to tech like BT2020 color space or HDR.

So, since Faux-K doesn’t have a clear definition, the one I’ve been using the past few years is simply this:

If a projector can’t put up 3840×2160 pixels without pixel shifting (call it overlapping pixels), but can input 4K content and display it, that’s my definition of true 4K, and that’s the one we use in our reviews.

If it’s a projector I call Faux-K it’s probably a 4K UHD projector, or a 1080p pixel shifter, but conceivably there are other ways to put at least 8.3 million pixels on the screen. (Not that they make sense.)  Normally when I am talking 4K  content capable, I’m always trying to be clear whether it’s a 1080p pixel shifter, or now that we have projectors with the new TI chip, also 4K UHD aka a 1528p pixel shifter. or a true 4K projector.

OK, regarding that early Faux-K reference, that far back I recall an article by Andrew at HomeTheaterReviews, from 2011, of him using the term to describe pixel shifting 1080p projectors that accepted 4K content.  In light of recent conversations with various manufacturers about 4K resolution of late, I’m reminded of follow up his and JVC’s follow-up comments is one of the forums.  There he  and JVC debated whether their projectors were being misrepresented by using terms such as 4K Precision.  It’s an interesting back and forth.  The point being, the term Faux-K (or FauxK) has been batted around quite some time, without a clear definition of what Faux-K is, only what it’s not.

As far as the terms go, FauxK vs 4K, I pretty much treat Faux-K as a fun term to describe competent projectors that are capable of accepting 4K, but can’t pass my “true” test..  Manufacturers should not be offended.

Between 4K, Faux-K, and the addition of HDR, and BT2020 color space, things are still a bit murky as we all scramble to understand the benefits, and limitations, and how to maximize the viewing experience when there are trade-offs.  In addition things will be changing at a healthy pace going forward. Hang on for a ride.  -art

 

News And Comments