Master Guide to Home Video
In recent years, home video technology has made enormous progress, and it continues to make more progress at an exciting pace. Products have become better, and more affordable. And video technology has become more diverse, thereby encouraging competition among various technologies (not just among products of a common technology) to bring you better video and more affordable video.
This, then, is a report in progress on a technology and an industry in progress. We'll look at where we've been, where we are, and where we're going in video. And we'll keep all this in mind for our product recommendations, so they can be wise advice to you, not merely faddish gossip about the newest hot flashes in the pan. This master video guide is a companion piece to IAR's Home Theater / Surround Sound guide, which you should also read (in IAR issues #68-70, which are part of IAR volume 6).
Before we get into technical details, let's first get a firm overall understanding of what we really want from our video system. We should first know what our ultimate goal is, before we search for the best way to get there. If money and technology imposed no barriers, what ideally do we really want from a perfect video system?
I think the answer can be given in one word. Believability.
Some others might say spectacle, or excitement, or entertainment. Indeed, most video demos are intended to impress you, overwhelm you, even assault you, with razzle dazzle fast action spectacle and high adrenaline entertainment. If a salesman has only a few minutes to grab you and sell you in his showroom, he's naturally tempted to try to sell you on this aspect of video. It's no secret that TV sets on demo in stores are all cranked up way beyond believable color intensity, contrast, and brightness, in order to assault you enough so that they'll grab your attention.
But all this is a mistake. Video should not be sold or bought on the basis of adrenaline. The temporary thrill of being assaulted soon fades, and most of us humans cannot live on adrenaline all the time. There are already reports of customers tiring of home theater, because they tire of being assaulted -- and that's the only thing they think home theater is good for, because that's what they've been taught, since that's how the products have been designed, promoted, and demo'd.
There's a more enduring human need, which good video can satisfy. When you come home after a hard day's work, you've probably had your fill of stress and adrenaline. Instead, you want to relax, forget your worries, and get transported to another world where your problems don't exist. If video is believable, it invites you in, into another world, and you're gone. Gone from this world, with its stress. Gone from your room.
This video believability phenomenon is similar to the audio believability that is so crucial to the success of home theater, as we have discussed in other IAR articles (especially IAR's Home Theater / Surround Sound issues # 68-70). With the audio of most home theater systems, you can hear five or more separate boxes pumping, screaming, and flailing at you, assaulting you in the confines of your listening room. You can sense that you are trapped in your small room with these individual speakers sonically assaulting you from various angles. These speakers sound too distorted, too unnatural, too screechy, too boomy, too loud, and above all, too localizable and too localized within the four walls of your small room. As the visual scene plays out before you on screen, your ears and brain keep reminding you that you are here, not there. You are here, trapped in a small room with multiple separate speakers assaulting you. But instead, you should be there, in the venue portrayed visually on screen. The inferior sound of this system won't let your brain believe. On the other hand, a home theater with superior sound can make your room aurally disappear. You can't hear where the speakers are within your room, or even that they are in your room, or indeed even that your room and its walls exist at all. You are aurally transported to the venue of the scene that's visually up on screen. The aural part of brain -- so crucially important that you can't turn it off (nature programmed you this way, so you'll hear a predator snapping a twig even when you're asleep) -- believes. And so you believe. In fact, a convincing sound system makes your brain's belief so strong that it actually improves the look and believability of the video you're seeing on screen. Good sound invites you in, and transports you to another venue, so you are there, not here in your small room. Bad sound assaults you in your room, and won't let you forget that you are here, trapped and being assaulted within the confines of your small room by multiple separate speakers.
Likewise, believable video helps you forget that you're in your small room, watching an image on a screen in your room. It helps you forget that you're even in this world, as it transports you to the other world portrayed on screen. On the other hand, poor quality video constantly reminds your eyes and brain that you're looking at an artifice within your small room. If the picture is too pallid, or too garish, has motion artifacts or grain or lines, then you're always aware that this is an artificial image painted within your small room. You never believe in the scene portrayed before you. You are never transported to that whole other world.
Imagine that there's a moderate sized rectangle on one wall of your room. Now, imagine firstly that this rectangle is a large photograph on paper. You look at the scene portrayed in the photograph, and you can easily tell that you're not looking at the real scene. You don't believe. The colors are too pallid, the contrast is too low, and the resolution isn't high or fine enough. Your brain isn't fooled for an instant into thinking the portrayed scene is real, and you are constantly aware that you're still trapped in your small room, looking at a photograph hanging on the wall within your room. Or, alternatively, imagine that this rectangle is a cel or print of a cartoon. You similarly don't believe that this is a real scene; the colors are too saturated and monotonic, the outlines are too straight and simple, and perspective is too flat or simplistic.
Now, imagine secondly that this rectangle in the wall of your room is a clear window, looking out into another world outside your house. You look at the scene portrayed via this rectangle, and you do believe. You believe that what you are seeing through this rectangle is real, and three dimensionally palpable (so you could reach out and touch it), even though the image formed on your retina is just as two dimensional as when you were looking at that photograph on the wall. You believe that you are now seeing another world outside the confines of your small room. And your attention, your interest, your fascination, your involvement with what you see within this rectangle is heightened tremendously by your believing in this other world.
Why do we treasure and gravitate toward those particular windows in our house that might have a view of mountains, lakes, meadows, or trees? Why do we take such pleasure and get such de-stressing relief from merely gazing aimlessly out through such a window? It's because we suspend disbelief, and allow ourselves to be invited into this other world we see beyond our window, as in our mind's eye we are metaphorically transported to this other world. Note that if being internally transported to that other world were not important to us, and if instead it were sufficient to merely look at trees or mountains, then it would suffice as well to merely hang a picture of trees or mountains up on our wall and gaze at that.
You can get that same soul nourishing transport to another world from video, if it is good enough to be believable.
If video is believable, then you can put it to all sorts of uses. Yes, believable video does increase the adrenalin rush of action flicks and sports even further. Yes, it can excite and entertain. But its powers are even more special when you put on a type of show you can relax to. There's nothing quite like the human feeling of relaxing and being swept away, of surrendering to a suspension of disbelief. That's magic. You're body is here, but your mind is there. Believable video can do this, because its quality is so believably good that it does nothing artificially wrong, to constantly remind your brain that you are merely looking at an artificial picture on the wall.
Unbelievable video is unbelievable because it can't fool your brain. It might look spectacular or hyped up, but it does something wrong that constantly reminds your eye/brain that it is artificial. No matter how much you try to enjoy the show, your brain can never truly suspend disbelief, so you can never fully relax and get swept away to another world.
Performance Factors to Look for:
-- Color Rendition
What are the chief factors that make video believable, that we should seek out in our video systems?
One of the most important is natural color rendition. Natural color rendition is dependent on both color range and color gradation. The video system's color range should be able to reproduce the strong, saturated colors sometimes seen in real world objects, and it should be able to do this well for all primary colors and all combinations thereof. Some video systems have trouble believably reproducing some portions of the color wheel (or matrix) with enough saturation or intensity, perhaps due to limitations in phosphors, etc. The video system's color gradation should be able to reproduce the subtle color gradations seen throughout the real world, e.g. in the complex color variations throughout the many flesh tones in each human face. Some video systems have trouble believably reproducing these subtle color gradations, and instead (for example) produce a single monotonic color for large patches of human flesh, resulting in (say) a human face that is too pallid (where the large patches are too pale) or alternatively too blotchy (where the large patches are too saturated).
Natural color rendition is so important to believability that one can forego other desiderata and still have a believable image, so long as the color rendition is executed superbly. We saw proof of this at CES, in an amazing demonstration modestly presented by Arcam, using their FMJ DV27 model DVD player. The film segment shown was unexciting - certainly not one of those high adrenalin action flicks typically used in demos to grab your attention and also to distract you with the film's exciting content, so you mistakenly think you're also seeing exciting, high quality video. Instead, this film segment merely showed a few human faces, and nothing exciting was happening in this scene. Thus, only the video quality was on display, honestly and without pandering distractions.
But this Arcam exhibit was riveting. We couldn't take our eyes off the video. Why? It wasn't the resolution. The video system presented only a modest 480 line vertical resolution, far less than the common 720 lines seen in most other exhibits, and far less than the state of the video art, as shown by Faroudja in their 1080p presentation. The display size was also modest, a mere 42" (diagonal) NEC plasma, whose image is actually only a puny 20" tall.
So what then was it about this Arcam/NEC display that riveted our attention? Quite simply, the believability of the human faces. In particular, the flesh tones were rich and yet subtly variegated within each face. The human flesh had an inner glow and a tactile reality you wanted to reach out and touch. That's believability!
On too many other video systems, flesh tones are too pallid and uniform, looking as if the makeup man had applied white flour to all the actor's faces. These other video systems sometimes brag about the high quality of their flesh tone, but they make the big mistake of speaking and thinking about flesh tone in the singular - and that's what their systems look like, as if all actors were wearing a mask with a single flesh tone painted over their whole face. Meanwhile, on some other video systems flesh tones are strongly saturated and distinctive, but are blotchy, lacking the subtle intermediate transition tones that allow subtle variation across every square millimeter of a human face, the very variation that's so crucial to allowing a face to look real.
Note that these other too pallid and the too saturated video systems share one flaw in common: they both lack subtle variations in flesh tone. We might not consciously look for this continual variation in color across a human face, when we passively watch (or even critically analyze) video systems, but we subconsciously instantly recognize the more believable reality it gives to human flesh when we finally see it done right. Without this continual subtle variation in flesh color, a human face looks almost two dimensional and flat, as if human flesh were only a superficial surface treatment painted onto faces. But when the flesh colors are properly variegated, they seem to glow from within (as a good pearl does), rather than merely residing on a surface, and then human flesh acquires a three dimensional palpability that you can reach out and touch, that you can believe in.
Obviously, we should begin using this parameter as a yardstick for gauging and comparing video systems; we should begin expecting and demanding better believability in reproducing the subtle, manifold variations in color of human flesh. When it's done right, human actors suddenly become believable. And then the drama of the plot gains additional force and cogency, because our eyes and brains now subconsciously believe in the reality of the characters on screen. Of course, a video system that can delineate the manifold subtle variations of human flesh colors can also be superior at portraying the naturally varying textures of all inanimate objects, so they become more believably real as well, thereby giving the entire film content and our entire video experience the believability that is our holy grail and ultimate goal.
That's the kind of believability we saw at this Arcam exhibit, and that's what made this demo so riveting and exciting, even though the demo system modestly had less than state of the art resolution and picture size.
-- Luminance Rendition
A second factor crucial to believability is natural reproduction of the luminance scale (the variation from light to dark). This is dependent on maximum achievable brightness, on maximum achievable contrast (from the blackest extreme to the brightest extreme), and most of all on the ability to portray subtle variations in brightness or luminance throughout the broad range in between the two extremes.
When you look out a window at the real world, you believe in what you see largely because there is often tremendous dynamic range in brightness, and infinite subtlety in the variations of brightness. Our eye and brain can take in and appreciate this large dynamic range and subtle nuance. But our video systems cannot reproduce an equally large dynamic range, and most also have difficulty reproducing varied brightness nuances (the gray scale) with sufficient discrimination, well within their dynamic range.
The era of black and white films forced us to learn to manipulate, modulate, and employ the luminance scale to advantage. The luminance scale, in the hands of master film lighting experts, can be so important that it becomes a frame of reference, a foundation for the whole story of the film (luminance contrast is the visual foundation of expressionist 1930s films and film noir, and the portrayal of what you don't see, in the huge dark areas and patterns, is as important as what you do see). The luminance scale can even become a virtual character in the film (for example, the shadow of bars across the heroine's face personified Fate pre-determining her destiny; or the absence of light in the form of an unusual oblique shadow across the face could personify the character's subconscious dark, nefarious thoughts). Even when a black and white film seeks to portray a scene and human faces in a straightforward manner, master film lighting experts can modulate the luminance across a face or object so that it becomes extraordinarily three dimensional, glowing with a palpable reality you could reach out and touch.
It's worth noting that many color films fail to employ the same scene lighting mastery, perhaps from a mistaken belief that color variation is enough and obviates the need for creative luminance variation, so they merely light a scene flat (fully, without selective modulation), and as a result many color films look two dimensional, less believable and engrossing than their black and white brethren that do carefully modulate luminance. But a color film done with creative lighting could be just as three dimensional as a black and white film, indeed even more so, since the color variations produced by creative lighting can add even further dimension to the luminance variations. Colors change dramatically when exposed to different lighting (especially as seen by the camera, even more so than as seen by the naked eye which is inexorably connected to our color compensating brain). Thus, creative lighting allows the colors to subtly, gradually change across the span of a filmed object or human face, thereby giving it an extra measure of three dimensional believability and palpability. This creative modulation of color also applies to overall landscapes as well as single objects. For example, when you look at a real landscape, the colors for distant parts of the landscape are more muted than for nearby parts, due to natural effects by our atmosphere, and this change in color between nearby vs. distant portions subliminally tells our brain to believe in the three dimensional distance of the two dimensional image actually being formed on our retina.
The challenge for our video systems is to bring to us this believability that creative film (and video) makers have encoded in the luminance scale of their works. To get this three dimensional believability from luminance, your video system must have a wide dynamic range in its luminance scale, and also must be able to discriminate among subtle luminance variations within that overall dynamic range.
The practical dynamic range of a video system is determined by its maximum brightness capability and its maximum achievable contrast (which essentially tells us how black the blackest blacks can be, relative to the brightest output). Home video systems are usually severely challenged in trying to deliver sufficient brightness and contrast to portray a believable dynamic range of luminance. Issues of cost, practicality, technology, and consumer acceptance (for example, the brightest systems require loud cooling fans), all conspire to handicap home video systems in this
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