Parallax barrier how does it work

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Post by dreamingawake » Tue Feb 01, am. Post by cybereality » Tue Feb 01, am. Privacy Terms. Skip to content. Quick links. To do this we are going to use what are called Parallax Barriers. This is the same technique used on the Nintendo 3DS. Please make sure to watch the video above so you have an idea of what we are doing here.

I also quickly explain what a Parallax Barrier is and how it works. Basically what it does is selective block certain pixels from one eye or the other. So with properly authored content, we are able to deliver one image to the left eye, and a different image to the right eye. This concept is actually not anything new, it had been discovered over years ago. However it is just recently being applied to commercial products. In the next year years I think there will be a lot of development in this space.

Specifically with portable devices like the Nintendo 3DS. But you don't have to wait for companies to bring this technology to the home. Well, technically, you do need a certain amount of supplies and tools in order to complete the project.

But the actual parallax barrier itself and the ink you use to print it will only cost a couple of bucks. Monitor Obviously you need a monitor in order to mod it.

Any LCD computer monitor can work, although it should be 24" or less. Although there is no technical reason a larger size wouldn't work with a parallax barrier, the problem is finding transparency film in that size and having access to a large-format printer which are prohibitively expensive.

Practically speaking, you are better off sticking to 24" or less, as that means standard Super B sized transparencies can be used. Larger sizes are possible using transparency film rolls, however this gets expensive real fast.

It can handle up to x dpi. The other printer I have is the Samsung ML mono laser printer. The Samsung can handle up to x dpi.

Although I was able to make good progress testing things on this Samsung printer, the accuracy was not good enough get the quality I wanted. So make sure you have a decent printer if you want to attempt this. Although the supplies are pretty cheap, so its not a big loss to try it even if you don't have the best printer. Since it can print wide-format 13" x 19" that means I can completely cover a 22" widescreen monitor with one single sheet. If your printer only supports 8. I have tested this, and you can still play games like this, although clearly the wide-format is a better option.

Keep in mind that the barrier pattern is just printed in solid black, so a monochrome printer is fine. Specifically the models for laser and for injet, both are 8.

Other brands should also work, just make sure you get the right kind for your printer. It is used to cut the transparency film so it will fit on the monitor or to get a nice clean edge if you are attaching multiple sheets. You will want to get a large one, I used a 16" with cork backing.

Transparency Tape I used some transparent tape to mount the barrier sheet onto the monitor. This is the glossy kind that is completely clear not the foggy matte finish you usually find. This program is used to create the parallax barrier pattern itself, so you will need to be able to define your own custom patterns.

We will also use it to print the pattern. The iZ3D driver is a commercially available 3rd party driver that hooks into DirectX and converts any off-the-shelf game into stereoscopic 3D. Although not every single PC game is supported, there are probably close to games that will work with it some to better effect than others.

We will be using the "Interleaved" mode in the "Vertical" setting. Its basically just a bunch of straight lines.

The difficult part is finding the exact width for the barrier line that is going to coincide with your monitor. If there is any inaccuracy all you will get is a muddied, discolored double-image with no 3D effect.

So the crux of this project is just finding this magic number. Pretty much all monitors will have their dot pitch listed in the spec sheet, so this gets us into the ballpark right off the bat.

However there are other factors that effect the sizing of the barrier, such as the thickness of the glass on the screen, the thickness of the transparnecy film, your interpupillary distance IPD; the distance between your eyes , and the distance you are sitting from the monitor although this can be easy changed. I'm sure someone smarter than me could have come up with some formula to take into account all these values.

However, at the end of the day, its all about what you percieve with your own eyes. So I developed this project mainly based on a trial and error method. There is, however, some math involved but it should be easy to follow. This is dependent on the DPI of your printer. You always want to be printing at the maximum DPI your printer can handle. Keep in mind that many printers have different horizontal and vertical DPI resolutions. So you may be limited by the lesser of the resolutions.

I recommend having at least dpi, although it may be possible at lower resolutions but I think the quality would suffer. Say your printer did dpi. If you used a ppb resolution, then there would be 6 opaque barriers per inch plus 6 transparent spaces the same size as the barriers. Unfortunately, the barriers must be a lot smaller than that, and more precise. They need to match up exactly to the width of a single pixel on the monitor actually less than that, since you have to take perspective into account.

So this is the magic number we are looking for. Dot Pitch The first thing you need to do is find the dot pitch of your monitor. This will be in millimetres. So what we need to do is convert this dot pitch into a pixel-per-barrier value.

Since printers use dpi dots-per-inch we need to convert millimetres into inches. This is pretty simple to do. We just need to figure out how width a pixel is in inches. You can simply type this into Google: "0. That will give you the width of each pixel in inches. Now to get the pixels-per-barrier we need to multiply that by the dots-per-inch of the printer. I am going to use the value of dpi, since that is what my Epson does. Note the actual value should be smaller than this, since the barrier is in front of the panel and we need to take perspective into account.

The problem now is that there is no printer certainly not on the consumer market that can printer with that kind of accuracy. I mean, it seems really close to 16 pixels, but thats not good enough. Although at this point you should print out a barrier of 16px or whatever the closed integer is just to see where your at. Creating the pattern This is actually the easy part. Just fire up your favorite image editor. The eye tracking combined software provides right images for the respective eyes, therefore producing no pseudoscopic effects at its zone boundaries.

The viewing zone can be spanned over area larger than the central viewing zone offered by a conventional PB-based multiview autostereoscopic 3D display no eye tracking. Our 3D display system also provides multiviews for motion parallax under eye tracking. More importantly, we demonstrate substantial reduction of point crosstalk of images at the viewing zone, its level being comparable to that of a commercialized eyewear-assisted 3D display system.

The multiview autostereoscopic 3D display presented can greatly resolve the point crosstalk problem, which is one of the critical factors that make it difficult for previous technologies for a multiview autostereoscopic 3D display to replace an eyewear-assisted counterpart.

A stereoscopic display, the so-called three dimensional 3D display is the device that enables a viewer to perceive depth of an image of a given object as well as its two-dimensional one.

The conventional 3D display with the binocular parallax provides two different view images via mandating a viewer to wear the eyewear such as eyeglasses or a specially designed headset. This eyewear is designed to receive right images for respective eyes of a viewer by using optical polarization filtering spatial multiplexing of images by a polaroid [ 4 , 5 ] or time-resolved redistribution of two different images temporal multiplexing of images by a view-synchronized shutter [ 6 , 7 ].

Widening of the eyewear-based 3D display market has been in progress for cinemas, laptops and monitors. Thus, the eyewear-free 3D display, the so-called autostereoscopic 3D display has come to much attention, and the numerous types of autostereoscopic 3D displays have been proposed and demonstrated. Examples included an autostereoscopic 3D display by methods of temporal multiplexing of view images with light guiding optics [ 9 , 10 ], holography [ 11 — 13 ], by the focused light array FLA [ 14 ], and by the specially designed optical plate [ 15 — 19 ].

The temporal multiplexing method that could provide image resolutions similar to that of a 2D display, however, needed a sufficient speed at which display panel image signals render, their processing bandwidth being in proportion to the number of view images for a 3D display. The holography-based display was capable of providing the most natural 3D images. In the meantime, the FLA method that used the video raster scanning of light emerging from the co-focal point of image illuminance, where light arrays of different views were focused, offered an advantage of image resolution comparable to the current monoscopic 2D display.

However, this method exhibited drawbacks of high fabrication cost, the bulky system size, the point crosstalk much higher than a commercialized eyewear-based 3D display. The optical plates used for this purpose were usually subgrouped into two kinds, i.

The conventional methods that used optical plates, however, had encountered a serious problem, i. Reduction of point crosstalk in a multiview autostereoscopic 3D display has been achieved by various methods such as by using a V-shaped PB [ 21 ], by assigning variable weight factors to individual display pixel illuminance [ 22 ] and by reducing width of optical beams that emitted from multiple projectors via lenticular lenses [ 23 ].

However, the point crosstalk needed to be reduced to the typical level of an eyewear-assisted stereoscopic 3D display, i. Head tracking technologies have been combined with multiviews to offer autostereoscopic display to viewers of various interpupillary distance and the related analysis on the view numbers has been reported to provide 3D images without inter-view dark zones [ 27 , 28 ].

We control display pixels via software coding for display signal rendering upon real-time monitoring of eye positions of a viewer who is allowed to move within a limited range along a horizontal line at a given optimum viewing distance OVD from a display panel motion parallax. The proposed 3D system that offers improved uniformity of image brightness and greatly reduced point crosstalk at an enlarged viewing zone, benefits eye fatigue reduction and improved 3D image quality, thus being considered a possible replacement of an eyewear-assisted 3D display system.

In a conventional multiview autostereoscopic 3D display with an optical plate of binocular parallax, e. These distributions that exhibit triangle-shaped distributions including abrupt changes in illuminance around the so-called sweet spots, produce non-uniform brightness of images and therefore can cause considerable eye fatigues.

Movement of a viewer from the sweet spots of no point crosstalk, begins to produce rapid increase in overlap between adjacent view images, therefore rapid increase in point crosstalk, as checked in Fig.

DP denotes the display pixels. Different coordinate systems are used to distinguish horizontal positions between on display pixel surface and on a viewing zone. However, in this section, we assume triangular distributions of image illuminance to simplify our discussion to highlight PB engineering concept. Let us define the point crosstalk of the k -th view image k :integer at a given x of the viewing zone for a N -view autostereoscopic 3D display, i.

First, in order to improve uniformity of illuminance distributions at around their sweet spots, we enlarged the PB aperture size in spite of expected increase in point crosstalk. Figure 2 a illustrates schematic of a PB-based 3D display system with an aperture size as about twice as that of Fig. A uniform illuminance distribution for each view image can be expected over the substantial part of the viewing zone while strong point crosstalk being created over the entire viewing zone as depicted in Fig.

Note that care has to be taken to design the display pixels and PB to ensure that more than one view images should be present between two eyes at the viewing zone. Then, we can anticipate that the removal of all view images by turning off corresponding pixels except images viewed by two eyes at the viewing zone can greatly reduce point crosstalk zero as shown in Fig. According to simulation, achievement of vanishing point crosstalk over a widened region of viewing zones at OVD is valid for W greater than approximately twice the subpixel size.

In addition, it is noted that this removal of view images that include those adjacent to view images seen by two eyes also can be expected to enhance uniformity of illuminance distribution around sweet spots.

DP: display pixels, PB: parallax barrier. For motion parallax, we employ cameras to track two eye positions, thus allowing the display system to determine which pixel is the closest to the center of two eyes. We exploit a software feedbacked from the position tracking cameras, which is coded to determine which pixels of a display panel to turn on while switching off the rest of them.

The software that renders signals to pixels upon tracked positions, then enables motion parallax to be provided, maintaining both substantial reduction of point crosstalk and greatly improved uniformity of image brightness at around sweet spots.

The software used consists of both the Face API and a self-developed software. The self-developed software recalibrates information from the Face API to refresh the image information at the speed of 15—30 Hz. It is obvious that the the area of a viewing zone remains similar when the slit size changes by two fold. However the wider slit size shown in b produces more number of yellow color shaded optical rays that converge from an entire area of a given display pixel surface through the slit on a given point within a viewing zone shown in a.

This optical property supports the widened viewing zone that exhibits uniform illuminance of a given view image. It is also found that a viewing zone shrinks in a horizontal sense at a viewing distance different from the OVD. This implies that the aforementioned benefits of using a widened slit of a PB under a dynamic eye tracking can be optimized at OVD. The viewing zone area remains similar as the slit size changes by twice.

However, the fact that the case of b allows more number of yellow shaded regions of optical rays which emit from an entire area of a pixel surface and converge on a point within a viewing zone than the case of a indicates the presence of a widened viewing zone that produces uniform illuminance of a given view.

We designs an 8-view autostereoscopic 3D display with the set of display parameters given in Table 1 for a given size of a subpixel of a laptop computer. The air gap needs to be carefully adjusted for view image formation at OVD. Based on this design, we conduct computer simulation of optical ray tracing from display panel pixels through PB slits to a viewing zone to obtain theoretical estimation of the 3D display characteristics which is compared with those achieved from experimental measurement of illuminance of the 3D display images of the same set of parameters.

First, we take a PB with its slit aperture of Simulation provides the illuminance distributions of view images at a viewing zone separated from the display panel by mm OVD of mm as shown in Fig. As mentioned above, we could observe Gaussian distributions of view image illuminance due to a PB orientation in relative to a DP, as shown in simulation and experimental measurements.

It is highly probable that the the value of a computed OVD designed to serve a viewer with minimum point crosstalk of view images cannot be the OVD mm in a practical setup due to both geometrical mismatch between the designed gap and fabricated one and presence of the medium glass in between.

We find that even the sweet spots of distributions produces We may attribute the difference in point crosstalk at sweet spots between simulation and experiments, to factors that include the slit period error of the fabricated PB and misorientation of a PB with respect to a DP. The point crosstalk is We enlarge the PB slit aperture from Figures 5 a and 5 b show simulation results of illuminance distributions of view images versus x at OVD of mm before and after elimination of 3 intermediate view images, respectively.

Note that the centers of the nearest neighboring view image distributions are separated by about Thus removal of 3 intermediate view images between view images seen by two eyes of a viewer, produces no point crosstalk over a zone of about 44 mm width around each eye of a viewer and these zero point crosstalk zones feature perfectly uniform distribution around their centers, as shown in Fig.

The two advantageous properties of illuminance, reduced point crosstalk and enhanced brightness uniformity, are beneficial for better image quality and mitigation of an eye fatigue.

Note that Fig. The software redistribution of images includes aforementioned elimination of intermediate view images. In this case, there are no pseudoscopic effects thanks to eye tracking combined software that provide right images to the respective eyes.

Point cross talk averaged over each viewing zone bounded by the dotted lines is given in blue for a left eye and in red for a right eye. Figures 6 a and 6 b show measured distribution of view image illuminance at OVD of mm, before and after removal of 3 intermediate view images between both eyes of a viewer.

It is noted that, unlike simulation results of Fig. Never could the significant point crosstalk be absent even at around the centers of illuminance distributions of view images before eliminating those intermediate view images, as illustrated in Fig.

We also observe approximately uniform distribution of view images at around centers of both eyes of a viewer despite the overall change in illuminance along the horizontal axis due to the Lambertian light source as addressed above. Similarly to Fig. However, the further enlargement of the slit aperture, i. Furthermore, removing 3 intermediate view images between both eyes of a viewer generates a viewing zone of no point crosstalk as wide as Receive Erratum Email Alert.

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