In previous articles I described the differences between active-shutter and passive polarized 3D technologies, as well as the subject of “perception” endorsed by the passive polarized 3DTV camp. Graphs and descriptions may get in the way of understanding the concepts so perhaps we should describe the subject of brain perception vs. true image quality with an analogy that may be less complicated than comparing the nuts and bolts of 3DTV technologies, as I did in other articles.
Imagine spending your Saturday visiting new car dealers. Regardless if you could afford them or not you always admired the quality and performance of Porsches, Ferraris, and BMWs, and the elegance of Cadillac, Lincoln, Lexus, and Infinity, but have not decided which car to buy yet, so you are open to suggestions and may even want to experiment with new technologies and features.
In a way the experience is similar to looking to buy a new HDTV, a TV with a quality image and great performance, which you want to bring home to start your enjoyment. However, for most people, evaluating 3DTV technology is more complicated and taboo than evaluating a car ride or interior, or I should rather say “people could get easily fooled when evaluating a 3DTV”.
An ideal 3D system would be able to take the original 1080p pair or images as they were recorded by the 3D cameras and display them simultaneously to both eyes, without diminishing per-eye image resolution (consumer passive system), or alternating images (active system, panels and projectors), or displaying a second image with inverted pixels (LG’s passive method). Other than some hi-end projection systems (including 4K, dual projectors, etc.) there is no panel or projector that is capable to do that at a reasonable consumer price found at Best Buy over the weekend.
One could imagine that high level of quality to be the Lamborghini’s of the cars industry (or your dream choice of exuberant performance cars). Realizing that you would not come back home with a Lamborghini, you still entertain and hope for the possibility of a reasonable priced Porsche, a performance level that is lower than the dream 3D above, perhaps equated to active shutter by those which vision does not get affected by the way active-shutter operates, otherwise the performance level is irrelevant, the decision becomes subjected to what your vision (or pocket) can tolerate, and passive can be regarded as the savior on the 3D hope. Luckily both technologies coexist “and should coexist”, like the Yugos, Porsches and Lamborghinis.
You have arrived to the car dealers’ street and a big magnet pushes you toward the Porsche dealer, but close to it you spot a new dealer with an ad banner that catches your attention. The ad says: “our car will make you perceive the ride like the Porsche next door. There is no need to pay attention to the performance of the engine, the wheels, or the transmission if the ride feels good enough for you”.
You wonder how is that possible, and notice that the wheels on this wonder-car work in an odd way, they seem not to do full turns, they only do a half-turn on each side of the car at the same time, then they stop, then they turn half-way again. The dealer says: due to engine and transmission efficiency (rather limitations) we made the car so it “is perceived” to be in constant forward movement even when the partial rotation of the wheels need each other to complete a full turn.
The dealer adds: One may think that sharing the half-turn among two wheels may result in a degraded performance, but many people that drove the car for a few minutes in the parking lot do not notice that the wheels work half-way, they perceive the ride as if the wheels are doing full turns all the time, and that is what it counts, the dealer said, “your perception”, what your brain thinks the car is doing, not the mechanical performance measured by industry’s tools and standards.
[Back to 3DTV] One may equate the half-rotation per wheel to the typical half-resolution-per-eye of passive 3DTVs, whereby half of the video lines are displayed per eye and both eyes are needed to see the full image, not just the depth of the image. LG claims that the 3D effect is perceived as full resolution by people’s brains.
[Back to cars] However, since you are traditionally interested in performance and quality, you rather have a car with wheels that perform full turns. You consider the visit to this dealer useful as an exercise in researching alternative technology but decide to move on toward the Porsche dealer next door.
But when about to leave, the corner of your eye grasps another version of the same car on the dealer’s floor, you get closer and its window displays a graph, it shows other style of operation, as follows: during the time a wheel is not doing the half-turn forward it uses the engine and transmission to do something else. Wait, you think. Wasn’t the concept of two half-wheel-turns good enough for a perception of a smooth ride (you ask the dealer)?
The dealer says: we thought about people objecting to the half-wheel-turn operation (regular passive 540 video lines per eye) and because of that we designed this other system so we can claim our car powers the wheels to turn more like our competitors do (full resolution active-shutter 3DTVs). We are very proud of our system because we found a way to maximize the limited capability of the engine and transmission designed to only power half-turn cycles for the left and right wheels (typical passive 3DTV), this model applies additional bursts of power to the same two wheels after they stop their half-turn (LG’s FPR passive 3DTV on the second 120Hz cycle).
You see (the dealer says), on the first half-turn of the wheels (first 120Hz cycle of LG’s FPR passive 3DTV) the engine and transmission rotates the two wheels forward half-turn each, then an additional burst of power (second 120 Hz cycle of LG’s FPR passive 3DTV) makes the wheels rotate half-way again. We are proud of this design because it can claim all the wheels are constantly moving (displaying the full resolution of 3D Blu-ray, as claimed by LG Display), however, between you and me, due to system limitations the wheels can only turn in reverse on the second cycle. Turn in reverse (you said)? How can a car be perceived to move constantly forward when the wheels are turning in reverse half of the time?
Shhhh! Says the dealer. Nobody notices and we do not explain unless we are asked. The dealer explains that the two reverse half-turns on each wheel are so brief that the movement “is still perceived” as a constant forward rotation when the driver sits on the back seat stretching the arms toward the front to reach the steering wheel to avoid noticing the 540 horizontal defroster lines across the whole windshield. The black lines are needed for the system to work and since they are thicker than regular rear-window defrosters they block the viewing of the road when sitting too close from the windshield, the dealer says.
[Back to 3DTV] This is similar to viewing a 3DTV from far away to avoid noticing image imperfections and the Frame Patterned Retarder (FPR) of LCD passive 3DTVs. LG recommends a viewing distance of 15-feet from their 60” 3DTV, when the recommended viewing distance is traditionally 3 times the image’s height (or 7-8 feet for that 60” 3DTV).
[Back to cars] The dealer adds, the technology is so smart and we made it so complicated that people think the wheels are turning in the same direction, and again “perception is what counts” and this way we can claim the full wheel turning of Porsche, moreover, with this (3D passive in two 120Hz cycles) technology we (LG Display) are taking the whole car (3DTV) industry by storm. You can even use the same sunglasses you use in a Lamborghini (local theater).
You have to test drive this car (you say to yourself), and you do, is not as bad as you thought, it rides different, and it may be perceived by your grandmother as moving constantly forward when driving from the back seat as the dealer said, but not to you, besides, who wants to drive from the back seat and have obstructed view of the road just to perceive the car’s movement as constantly forward?
Additionally, regardless of the “perception”, the fact that you know the wheels are moving forward and then moving backward all the time makes you skeptical about actual performance, safety, and braking during snow and rainy days.
Then you looked at the sticker price, and your eyebrows did the talk. And you asked: I was expecting a lower price if the engine and transmission have design limitations to just work with half-turning wheels; why is it that the price of your car is similar to the Porsche next door? (Active-shutter 3DTV). And the dealer says “have you seen the low-cost sunglasses that come with our car for extra passengers?”
The dealer said that the manufacturer (LG Display) decided to build this car because their experts determined that a minority of people felt nausea or discomfort while driving Porsches and some even noticed visual flickering while seeing the street scenery moving thru the windows, the dealer said. [And I add, however, many of those same people actually felt similar discomfort issues when riding in buses (3D local movie theater)].
Furthermore, the dealer said, we believe everyone must stop buying Porsches and Ferraris and buy our better car, even those people that do not suffer nausea or visual flickering on the windows should do that. So we promote our models by aggressively advertising that Porsche and Ferrari (i.e. Sony and Samsung) should better stick to only make slow speed cars (2D) for neighborhood driving, and let us have the whole auto market (3DTV) for ourselves, regardless if the majority of people actually have no issues with Porsches turning the wheels with full rotation, or looking thru the windows.
Additionally, you should know that Porsche includes only one high-priced designer-performance sunglasses (active-shutter 3D glasses) for the driver, while our car (passive 3DTV) comes with four sets of low-cost generic sunglasses (polarized 3D glasses), many people did not even come to the dealer to test-drive our car, they bought it in the Internet just because it comes with low cost sunglasses and buyers think about the savings for extra passengers, besides, our glasses are also compatible with the windows of public buses (local 3D theater projection systems).
Welcome to the world of “good enough perception”, are you in? Your call.
Posted by Rodolfo La Maestra, December 5, 2011 8:09 AM
About Rodolfo La Maestra
Rodolfo La Maestra is the Senior Technical Director of UHDTV Magazine and HDTV Magazine and participated in the HDTV vision since the late 1980's. In the late 1990's, he began tracking and reviewing HDTV consumer equipment, and authored the annual HDTV Technology Review report, tutorials, and educative articles for HDTV Magazine, DVDetc and HDTVetc magazines, Veritas et Visus Newsletter, Display Search, and served as technical consultant/editor for the "Reference Guide" and the "HDTV Glossary of Terms" for HDTVetc and HDTV Magazines. In 2004, he began recording a weekly HDTV technology program for MD Cable television, which by 2006 reached the rating of second most viewed.
Rodolfo's background encompasses Electronic Engineering, Computer Science, and Audio and Video Electronics, with over 4,700 hours of professional training, a BS in Computer and Information Systems, and thirty+ professional and post-graduate certifications, some from MIT, American, and George Washington Universities. Rodolfo was also Computer Science professor in five institutions between 1966-1973 in Argentina, regarding IBM, Burroughs, and Honeywell mainframe computers. After 38 years of computer systems career, Rodolfo retired in 2003 as Chief of Systems Development from the Inter-American Development Bank directing sixty+ software-development computer professionals, supporting member countries in north/central/south America.