by Oleg Artamonov
10/26/2008 | 03:22 PM
We have recently published a review of Zalman’s Trimon ZM-M220W, a monitor that can produce a stereoscopic or three-dimensional image. You may remember that the images for the left and right eyes were separated in that monitor by means of interlaced polarization. When you wore special eyeglasses (a passive device without any electronics), one eye saw only odd-numbered lines of the screen and the other eye saw even-numbered ones.
This method of creating a stereo image is not without drawbacks. It produces a three-dimensional, full-color and absolutely sharp picture indeed, and you can also use the monitor for both games and work, but the vertical resolution of the screen is reduced by half in 3D mode, and the interlacing of odd and even-numbered lines is noticeable in 2D mode. It seems as if the distance between the lines of pixels is increased in the matrix and you can clearly see the gaps.
However, Zalman is not the only maker of universal stereo monitors that support both 2D and 3D mode. I will tell you about the Trimon’s main opponent in this review. It is called iZ3D.
While the Trimon employs a matrix whose even- and odd-numbered lines produce light with different directions of polarization, the iZ3D goes further and employs two LCD matrixes of the same size (22 inches) and resolution (1680x1050 pixels). The operating principle of this monitor is based on the ability of liquid crystals to turn the polarization plane of the passing light by an angle that depends on the position of the crystals. This property is in fact used in every regular LCD monitor: the panel with liquid crystals is nestled in between two polarizers and the turning angle of the crystals determines what percent of light can pass through those polarizers.
So, the first matrix in the iZ3D is an ordinary LCD panel that produces the image proper. The polarization plane of its light is the same for every pixel of the panel. Intensity of light differs only.
The second matrix on top of the first one lacks polarizers and cannot regulate the intensity of light, but it can rotate the polarization plane of light emitted by specific pixels of the first panel by a certain angle. The human eye cannot normally perceive polarization, so the second matrix of the iZ3D looks just like a gray translucent panel.
But when you put on eyeglasses with polarizers set at 90 degrees to each other, the picture will be different. Now the amount of light for each eye depends not only on the brightness of the first panel but also on the polarization angle of light which goes out of the second panel.
One solution you may think about is to create something like Zalman’s Trimon: the second panel can be set up in such a way that its odd- and even-numbered lines made up different pictures and the eyes saw different lines when wearing polarizing eyeglasses. But like with the Zalman, this would reduce the effective vertical resolution twofold. We might use a tessellated pattern instead of odd- and even-numbered lines, of course… Anyway, in this design we somehow forget that the second matrix is an ordinary LCD panel and its state can be changed independently for each individual pixel at any given moment.
The iZ3D developers didn’t forget that. In their design each pixel of the first panel shows a combined picture for both left and right eyes whereas the second panel separates them. It is better explained with examples. For example, the right-eye lens of the eyeglasses has a polarization direction of 0 degrees and the left-eye lens, 90 degrees.
Suppose we need to show white to the left eye and black to the right eye. In this case the first panel of the monitor displays white and the second panel is set to a polarization of 0 degrees. As a result, the left lens lets the light pass while the right lens obstructs it.
What if the picture is then inverted so that the right eye saw white? The first panel doesn’t have to change anything. It is only necessary to turn the polarization plane by 90 degrees in the second panel, and the eyeglasses will show you a different picture.
And what if both eyes must see gray? It is simple: if the polarization plane is rotated by 45 degrees with the second matrix, each lens will let half the light pass and each eye will see gray. Note that this can be done for each out of the 1,764 million pixels individually.
To cut it short, the adjustment of the angle of polarization with the second matrix from 0 to 90 degrees changes the distribution of light from the first matrix between the right and left eyes. Thus, two things are needed to create a stereoscopic image on the iZ3D:
The advantages of this design are obvious. To start with, this monitor can work as an ordinary 2D monitor. It has a full resolution of 1680x1050 for both 2D and 3D modes, and a full refresh rate of 60Hz in 3D mode. It works together with passive eyeglasses. One drawback can also be noted right away: the maximum brightness of the screen is not high, especially in 3D mode, because the light from the first matrix is distributed between the two eyes, so the effective brightness of the screen is reduced twofold. Some light is also additionally lost in the second matrix. This drawback is hardly serious, however. Ensuring a higher level of brightness for an LCD monitor is a technical problem that can be solved by employing more powerful backlight lamps.
Thus, the iZ3D represents an interesting solution and its method of creating a stereo image seems to be more promising than the one employed in the Zalman Trimon.
The case of the iZ3D is made from black matte plastic, a light band on the side panels being the single adornment. The case is rather massive. It is definitely heavier than most of modern flat models, obviously due to the two LCD matrixes.
The stand allows to adjust the tilt of the screen. You can’t adjust the height of the screen or turn it around the vertical axis. There is a massive steel plate in the sole of the stand, so it makes the monitor very steady.
You can fasten the monitor on a standard VESA mount using the threaded holes in the back panel.
The LCD matrix has a glossy coating: it reflects the interior of our test lab in the photo above. Comparing the iZ3D with the Trimon, the latter seems to be more mirror-like.
The bottom of the case curves forward a little, putting the controls at your disposal. The buttons are standard: opening the menu, moving up and down, automatic adjustment, and power on/off.
I was most surprised to find that the monitor’s menu consisted of only one setting of Brightness. There are no other items, sections or options in the menu besides what is shown above.
The iZ3D does not support software-based control, either. At least, Nicomsoft Display Tuner reported that it lacked a DDC/CI interface.
The Power indicator is located next to the corresponding button. It is blue at work and amber in sleep mode. Unfortunately, this indicator is blinking at a frequency of a few hertz, which is somewhat irritating. It is only shining constantly when the monitor and system are ready for stereo mode (I will explain this shortly). You cannot get rid of the blinking of the indicator in sleep mode.
The monitor is equipped with two digital DVI-I inputs and one analog D-Sub. It must be connected to the graphics card with two cables to enable stereo mode. That’s not a problem if you use a single-monitor configuration because modern mainstream and top-end graphics cards all have two DVI outputs. If you’ve got a dual-monitor configuration, you’ll have to buy a separate card for the second monitor. The Front and Back labels next to the connectors correspond to the front and back LCD matrixes of the monitor. The former rotates the polarization plane while the latter produces the image.
It is not easy to access the connectors. They are covered with the wide pole of the stand, and you have to lay the monitor on its side to attach the cables.
Two pairs of eyeglasses are included with the monitor. There are also clip-on lenses for people who wear ordinary glasses with diopters. The included eyeglasses have curved-in ends of the temples that press on your head behind the ears quite hard.
As I wrote above, the eyeglasses are two polarizers with polarization planes set at 90 degrees to each other. The monitor is working in ordinary 2D mode in the photo above: you can see that one lens is transparent while the other does not pass the light from the screen.
The iZ3D can work in 2D mode, being similar to a regular TN-based 22-incher then. It has a resolution of 1680x1050 and a refresh rate of 60Hz. The second matrix does not affect the image unless you take a look at the screen at a sharp angle from a side or from below: the screen then appears to have a specific shimmering texture under the glossy coating. This angle should be as sharp as 50-60 degrees to the normal, so it is virtually impossible to see this effect at normal work. The iZ3D is better than the Zalman in this respect because the latter’s screen appears to be ruled with thin horizontal lines.
For working in 2D mode you can just connect the monitor to your graphics card with one cable, using the Back connector. The monitor’s Power indicator will be blinking then, which is rather irritating. For the indicator to shine constantly, you must not only connect a second cable, but also extend Windows’ Desktop to the second monitor. This is not very handy. Although the second monitor is indeed present (it is the additional LCD matrix of the iZ3D), you can only see the picture it produces when you put on the polarizing eyeglasses. When working with the monitor in 2D mode, I would regularly lose the mouse pointer and I had to return it to the main display by moving the mouse left and up or put on the eyeglasses.
If Windows thinks that the graphics card’s main output is the one the additional matrix is connected to (via the Front connector), you will see an empty Desktop without any icons, Start button and mouse pointer. In this case you should exchange the cables or put on the eyeglasses (you’ll see the picture on the additional matrix then, even though somewhat vague), open the display properties window and mark the other display as the primary one.
The monitor is not calibrated well originally. Even without any tools I could see that its gamma was too low. The picture was faded, whitish, with too bright shadows.
And my measurements agree: the gamma curves all go higher than the ideal curve for gamma 2.2. As I noted above, the single setting in this monitor’s menu is Brightness. This is due to the necessity of accurate adjustment of the stereo mode driver for the monitor’s gamma curves. Any adjustment of the shape of the curves would require a modification of the driver’s operating algorithm. This is also the reason why all the color reproduction settings in the graphics card driver must be set at their defaults. The brightness is regulated by means of backlight modulation at a frequency of 271Hz and does not affect color reproduction. The iZ3D displays both darks and lights without problems through the entire range of the brightness setting. Color gradients are displayed without defects, too.
The color gamut is standard as today’s monitors go. It is somewhat larger than sRGB in greens and nearly coincides with it in reds and blues.
The iZ3D doesn’t offer any color temperature settings, so the table has only one column. The setup is sloppy: white is far warmer than gray, the difference between them amounting to 2500K.
The corresponding dots on the CIE diagram show that white has a greenish hue, but it is barely noticeable. The eye perceives parasitic hues in grays better, but there is almost no hue in gray here.
The maximum brightness in 2D mode is about 240 nits, which is more than enough for office applications and movies, but you should keep it in mind that the level of brightness is twice lower in 3D mode. Therefore it is preferable to play at this monitor in a dark room.
The minimum level of white is 107 nits whereas it is recommended to have a brightness of 70-100 nits, depending on ambient lighting, to work with text. To achieve this value you have to set the monitor’s brightness at 0 and then additionally lower it in the graphics card’s settings. You’ll have to reset the graphics card’s settings to their defaults before enabling stereo mode, though. Otherwise, there would be more artifacts in the 3D picture.
The monitor boasts superb uniformity of brightness. The average and maximum deflection of white brightness are 4.4% and 12.7%, respectively. For black brightness, the average and minimum are 3.0% and 8.9%, respectively. As the pictures based on the measurement results show you, the sides of the screen are somewhat darker than the rest of it on white. Black is totally uniform.
The monitor doesn’t have response time compensation and is not fast as the consequence. Its response time average is 14.4 milliseconds (GtG) with a maximum of 30 milliseconds. These are typical numbers of RTC-less monitors that have a specified response of 5 milliseconds. The iZ3D doesn’t differ from them in this respect.
So, even though the iZ3D is not set up perfectly, it does not have any fundamental problems due to its stereo ability. To remind you, the screen of Zalman’s Trimon seems to have thin but conspicuous horizontal lines or gaps in between the pixels.
Anyway, I wish iZ3D developers improved the initial setup of the monitor and equipped it with a full-featured onscreen menu. It would also be good to have a button for switching quickly between different levels of brightness (like MagicBright in Samsung’s monitors) because the effective brightness of the monitor is reduced twofold when you switch into 3D mode.
Zalman’s stereo monitor could only work with Nvidia’s GeForce 6 or higher graphics cards, but the iZ3D is free from this limitation. It is compatible with graphics cards from both Nvidia and ATI/AMD. I performed the tests of the monitor on my standard testbed with a Sapphire Radeon X1650 Pro card (I had had to assemble a new configuration with a GeForce for the Trimon tests). SLI and CrossFire configurations are not supported.
I performed my tests in two steps, on different computers. The first computer had a Sapphire Radeon X1650 Pro graphics card with Catalyst 8.9 driver, Windows XP Professional SP3 with DirectX 9.0c (updates from August 2008). The monitor’s driver version 1.09.beta2 (build 1.08.0023) was used.
The second computer had an ASUS EN8800GTS/HTDP card (GeForce 8800GTS/512, ForceWare 175.19) and 64-bit Windows Vista Ultimate SP1. The monitor’s driver version 1.09.beta4 (build 1.08.0032) was used.
The developers from iZ3D recommend updating the monitor’s driver regularly because its newer versions offer support for more games. The lack of support for a specific game in the driver doesn’t mean it will be incompatible with the stereo mode, but an outdated driver may provoke hang-ups, performance hit and other problems. You can download the latest version from the iZ3D website.
By the way, the stereo driver of the iZ3D only supports games that use Direct3D (DirectX) 8 or 9.
The driver has a control panel that can do the following:
You can choose the way of turning the stereo mode on: automatically as you launch a game, with a hot button (it is the asterisk * on the numpad by default), or disable it altogether.
You can also set up the behavior of the control panel itself.
Of course, you can set the driver up for specific games. Particularly, you can define hot keys for turning the stereo mode on and off, change stereo mode parameters (spatial depth and convergence of the left and right images). Three Preset buttons are meant to switch through several presets but you can only specify one preset in the control panel. The buttons do work, however, so in the process of playing you can indeed experiment with three different stereo mode presets, quickly switching between them.
The driver identifies games by the name of the executable file. There are also generic settings for all unidentified games.
The pictures on the monitor’s two matrixes can get out of sync without vertical synchronization (VSync), so the appropriate checkbox can be found in the control panel. Of course, you can turn VSync on in the graphics card’s or game’s settings. You can also specify the default spatial depth (Separation, i.e. the level of separation of the pictures for the left and right eyes), shift the space left or right (Separation mode), enable the iZ3D driver’s messages (they inform you about the turning on and off of the stereo mode and changes of its parameters), and display the frame rate. The last option is interesting, but the result is predictable: the frame rate is two times lower in the stereo mode.
Besides the gaming driver, the iZ3D has a special player for viewing 3D movies and pictures. Such content must be originally recorded as 3D content. The monitor cannot add depth to flat images.
The viewing angles are quite good in the stereo mode. You don’t have to keep a certain position of your head. The picture gets distorted only when you deflect your head far from the center of the screen. The iZ3D uses linear polarization of light, so the image quality is affected if you tilt your head left or right.
By the way, the marketing folks’ favorite picture of a monster sticking out of the screen has little to do with reality. Perhaps if stereo monitors take off for real and game developers take them into account, we will really see monsters jumping out of the screen, but in today’s games the game world goes back from the screen but does not cross it.
I checked the monitor out in a few different games. I selected the stereo mode settings manually for each game, so the value of Separation varied from 10 to 20%. The Convergence parameter was selected in such a way that distant objects did not double.
I stopped my tests at that as I saw the trend quite clearly. The stereo mode worked normally (in every of the mentioned games) but was accompanied with noticeable artifacts that made gaming uncomfortable.
I can illustrate this with two series of photographs of the screen captured during my play in Far Cry. The first photo is each series is the monitor’s screen as it is. The second photo shows the same scene through one lens of the eyeglasses, and the third – through the other lens.
As you see in the first photo, the monitor really displays two images at once, showing the game world from two different points of view. The picture looks a fuzzy mess to an unaided eye.
The second photo shows the same screen for the left eye. There is one picture now, but not quite… You can see elements of the second picture, too: the red silhouette of the hand with the rifle, the white outline of the palm tree, and the blue outlines of the buildings. Thus, the left eye sees its picture and also a ghost of the picture intended for the right eye. Moreover, the picture has become warmer. This effect is not due to the camera’s settings as I processed all the photos with the same point of white.
The third photo shows the picture for the right eye. Again, there are traces of the other image, and the colors are now colder than the original ones! In other words, the eyeglasses bring distortions into the monitor’s color reproduction.
So, the overall result is unsatisfactory. Although the monitor gives you a depth of space, it also produces numerous artifacts that show up as shadows around both distant and close objects. As a result, you should not look at the weapon in your hands at all in Far Cry, for example. The picture gets noisy, making it hard to aim. And the eyes get tired in half an hour of play.
Right now the developers at the iZ3D forum report about a new model of the eyeglasses that should solve the mentioned problems. Judging by the latest posts, this model is ready to be released. I hope the improvements will be significant. The 3D image in games is indeed very impressive. If the iZ3D gets rid of the artifacts, it will be a most interesting product for every gamer.
The iZ3D stereo monitor left me with contradicting impressions. Its technology has superb potential but is currently accompanied with noticeable drawbacks.
As an ordinary “flat” monitor, the iZ3D doesn’t boast high quality of setup, yet it is better than the Zalman Trimon. As opposed to the latter, the iZ3D doesn’t have such artifacts that cannot be corrected with calibration. If set up accurately, it will be just as good as a regular 22-inch LCD monitor. So I have no doubts that the iZ3D is a truly universal monitor.
The stereo mode works, too. Unlike with the Zalman monitor, graphics cards from both AMD/ATI and Nvidia are supported, which makes the iZ3D far more appealing for those who have already bought a top-end card from AMD/ATI and do not want to replace it. The monitor supports Windows XP and Vista whereas Nvidia’s driver employed by Zalman can work only with Vista. The 3D picture has a resolution of 1680x1050 pixels and a refresh rate of 60Hz. Moreover, the iZ3D allows playing at nonnative resolutions stretched out to full screen whereas the Zalman Trimon can only produce the stereo effect when displaying the picture on pixel-per-pixel basis.
Unfortunately, these advantages are all negated by one defect. The left and right pictures are not separated fully, which leads to conspicuous and eye-straining artifacts in every game I have tried. Alas, this problem is so serious that I can’t recommend the iZ3D as a gaming monitor until the new version of the polarizing eyeglasses is released. Right now, both stereo monitors I have tested, the Zalman Trimon and the iZ3D, make you cry “wow” at first glance, but do not suit for continuous work or play either in 2D or in 3D mode due to various image quality problems. However, if the new eyeglasses help solve the mentioned defects, the iZ3D can prove to be far superior to Zalman’s model in both modes.