Okay, so the full title of this article is actually "The Immutable, Unchanging, Invariable, Unyielding, Ironcald, Permanent, Entrenchted, Unshakeable, Rigid, Steadfast, Everlasting, Perpetual, and Inalterable Rules...Part II." I'd have kept going, but the thesauras ran out. So did the space the editor said I could use for the headline.

But I think you get the point. In my last post, titled "Ten Steps to Movie Nirvana," I tried to outline some steps that, if followed, would be a short, reliable path to a better-than-average home theater at pretty much any budget. This was primarily aimed at someone starting from scratch. Then, after a re-read, it occurred to me that most of this readership had already committed to a system configuration of various "boxes" connected in some "workable" fashion.

TenCommandmentsMovie tablets2
Ignore the immutable laws of great home theater at your own risk! (Photo: Paramount Pictures)

Still in the quest of underscoring what's important to everyone's viewing enjoyment, I'm now offering a follow-up of essential considerations. Essential enough that it's worth re-looking at your own theater to assure you are compliant with at least these half dozen. I'll try to expand on the importance of each.


Anyone who has followed my musings over the years knows I have harped and harped on the importance of real contrast ratio. It is the single most important metric for realizing high impact imaging. To review, contrast ratio is simply the luminance distance (dynamic range) between absolute black and peak white...on the same frame! It is often referred to as "pop." The "new" pop is, of course, HDR. Because contrast ratio is so important, manufacturers tend to stretch the truth by manipulating how it is measured. Some years ago I asked one display manufacturer how the black level was measured and they said (with a straight face) "with the set unplugged."

We're looking for how much dynamic range the native panel or imaging device is capable of without any video processing. The correct measurement, at least the way I do it, is by dividing the peak white luminance reading (foot-Lamberts, candelas/meter squared, lumens, nits, flashlights per fortnight) by the minimum black level. Measuring adjacent black/white squares on a checkerboard pattern puts a fine point on it. Because the denominator (black level) has such a powerful influence on the ratio, so much attention has been given to that number. It is why we really like OLED displays with self-illuminating pixels that can be fully turned off-in other words, infinite black.

Room Contrast

Now that you have gone to great lengths to choose a projector that can minimize black level, an oft-neglected consideration in theater set-up is what the room is doing to your precious constrast ratio (C.R.). You would be amazed how fast an adjacent rack of equipment with its myriad of red, green, yellow, blue, amber indicator lights will kill previously established C.R. We call it "room contrast." Sometimes Aunt Martha likes to sit back in the corner of the room with a pin spotlight on her cookbook. That will do it for sure. Reflections from all the above off of glossy painted walls is another usual culprit. I have heard of a test at an ESPN studio in New York where calibrators were asked to wear black shirts while calibrating. Message here is that any light and reflections can cause a serious error, so don't fool yourself. If you like a certain amount of ambient light while watching movies, calibrate the black level there—it's the best you are going to get!

Cables & Connectors

Another surprise in this list of exalted "musts" might be cables and connectors. Joel Silver (of the Imaging Science Foundation) and I have written two articles on the need for speed with regard to ever increasing data rate transmission. To repeat, this is demanded by all the newest features, 4-4-4 chroma sub-sampling, 8K resolution, 12-bit color, UHD at 60 fps frame rate, yada-yada-yada. Are we done? Doubt it. Seems to me we are near the limit of visual acuity, but I've been wrong before. Connect boxes with the highest speed HDMI cables you can.

Projector Alignment

Tempting as it might be to correct a mounting error with a click or two of horizontal or vertical keystone correction, don't do it! Some scenes will be worse than others, but if you look carefully, the video processing will be trying to decide what size the picture is. It will guess wrong 50% of the time! Measure once, measure twice, use lasers, string until you are convinced it's dead on. Carefully measuring a white frame on screen will help.

So now, we've made the room about as good as it can be. Time to enjoy...

Premium Content!

Even if you have seen them before, they will be all new in 4K/HDR. If not offered in that format, they will still be better than before. Acquire some classics - Casa Blanca, Citizen Kane, Rebel without a Cause, Psycho... pour a glass of wine, turn off the phone...drift into the new world you have created.


Now comes an element I call "drama." Once you become accustomed to the "new" theater, you will be wanting to show it off. Host a Saturday night screening. Conduct a trivia quiz. Enhance the room yet again with a popcorn machine, motorized curtains, sconce lighting, a small candy counter and movie theme pillows.

That's it, folks...that's as good as it gets!

Oh, wait. There's one more...rule number 6B...


What a shame to go this far and not have it ISF-calibrated! Now you know it's as good as it can be....

Comments (8) Post a Comment
Mke Posted Nov 10, 2020 4:42 PM PST
Could you explain bias lighting and how it effects perceived contrast? Knowing that any light that hits the screen results in reduced contrast, would there ever be a case where bias lighting behind an ALR screen would be more beneficial than no light in the room at all?

Thanks much!
terrypaullin Posted Nov 10, 2020 5:05 PM PST
Mike, sorry for the delay - we have been experiencing E-mail problems. What we used to call a back light (now BIAS light) was solely used to reduce eye strain in an otherwise dark room. Now, with typical screen sizes 75 - 85" the light that the display emits is more than enough to eliminate eye strain. The native display light is what it IS the correct contrast.
David Petterson Posted Nov 11, 2020 4:24 PM PST
In your contrast section, I'm surprised you didn't mention white vs grey screens. I contend it's impossible to achieve a black image on a white screen. Simply because it's white AND then there is always adjacent light elements of the source. Also, is it possible for a source to produce a brighter white level (brightness) then what a projector is advertised to normally produce ? Case in point I have a Fleetwood Mac DVD that produces the brightest image Iv'e ever seen. It's just about blinding. Also, I don't understand how one cable (wire) can move electrons faster or "quicker"...(a measurement of time) unless it's made of a better conductor. Which over copper would be silver. Which I've never heard of being manufactured. As with room contrast. I find it amusing when I see a "theater" with walls (especially) near the screen that AREN'T black. Which due to decorators is usually some shade of red or blue. But it doesn't matter...right ? Dave
terrypaullin Posted Nov 11, 2020 5:12 PM PST
David - It IS possible for a white screen to produce black ONLY if the room is pitch black. Black, in this case is defined as the absence of (all) light.
IPD Posted Nov 12, 2020 11:33 AM PST
Output from an HDMI 1.0 device into an HDMI 2.2 on your projector is not going to give you 4k. Using a standard or lower-speed HDMI cable will also make it impossible to have a 4k output--as the cable will bottleneck the feed. The materials used in the cable are virtually irrelevant. In this way, it's similar to how USB works, and how full advantage of the newest USB standards cannot be utilized by USB 2.0 cables, etc.

As to room contrast, this varies by individual. I personally do not like an abjectly dark room to view in, as this tends to strain my eyes more than having some form of ambient or "nightlighting" to offset. There's a reason why cinemas have pathway/stair lighting--because it's painfully dark if you are trying to navigate anywhere. My suggestion is not to go for "pitch dark", but rather find ways to provide low-key forms of lighting outside of the direct visual of the projector screen (eg. under--seat lighting, indirect lighting behind the viewer, etc). I myself use an edge-lit shelving display at the dimmest setting. (Customized Designs 9" floating shelves, for those wondering). I suspect that edge-lighting a fixed-frame screen with max-dimmed LED strip lighting may also work...provided its done correctly. And by that, I mean that the strips would have to be virtually invisible and the light soft and blended enough so that there wouldn't be any "Bright spots" from individual LEDs.

And concur on manual image correction. One key thing left out here is that software image correction will almost always cause input lag. That alone should convince the user to do it manually.
Hal Chamberlin Posted Nov 12, 2020 9:37 PM PST
Cable "speed" really means the ability of a cable to transmit high frequency pulses with minimum distortion. Or more precisely, the "loss" of signal voltage at high frequency per foot of cable. The physical construction and properties of the insulation between conductors affects this more than the conductivity of the wires in the cable.
David Petterson Posted Nov 13, 2020 4:16 PM PST
So, you're referring to shielding in a cable or cross talk between conductors ?
terrypaullin Posted Dec 1, 2020 12:27 PM PST
Hal and David - In a coaxial cable it is the capacitance between the center conductor and the shield that 'shunts" the signal voltage. The longer the cable, the lower the signal. So Hal, you are right. - The "distortion" you speak of is just loss of signal amplitude. Of course there can be other culprits such as noise and magnetic pull.

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