In the home theater world, there is discussion of 4K video for the home. In fact, a number of the companies that make displays and projectors for home theater have announced their intent to deliver a 4K video experience to the home. As the monitors used as displays in video conferencing are based on these high-end displays and technology, is 4K coming to video conferencing soon? While it may not mean more resolution for the video stream, the use of 4K displays in video conferencing rooms may have great value in video conferencing rooms.
For those unaware, the 4K in "4K video" is based on the image having 4,000 (actually 4,096) pixels in screen width versus the 1,920 of today's "2K" HD displays. While today's typical top of the line display is 1080x1920 pixels, a 4K image is 2180x4096. The result is 4 times as many pixels on the screen. 4K is becoming common in theaters as it allows customers to sit closer to the screen and not see pixels. The first figure here (click here for larger version) shows a typical home theater and a commercial theater with viewing angles based on the Society of Motion Picture and Television Engineers (SMPTE) viewing angles. As can be seen, in the home, the viewers tend to sit at about the same distance from the screen, while in the theater there is a much broader range of distances. For this reason, 4K is needed for the closest customers.
While writing a white paper "Video Conferencing Display System Sizing and Location" (available at pkeconsulting.com), it became clear to me that for non-telepresence video rooms, the additional resolution of 4K displays could be very valuable. To understand why, reviewing the limitations of today's video displays in typical video conferencing rooms is required. The figure to the left (click here for larger version) shows the useable viewing range of a standard 60 inch diagonal HD (1080x1920) video display. This is shown in two ways; the angles show the acceptable minimum and maximum distances defined by the SMPTE. These are a minimum of 30 degrees and a maximum of 60 degrees. 40 degrees is the ideal viewing angle as defined by the THX video standard, considered the optimum in home theater. So the ideal seating for best viewing of a screen of this size is a little less than 6 feet from the screen. The blue box shows the range of viewing from minimum to maximum based on the SMPTE angles, and the solid blue line is the THX viewing distance (for more detail, read the white paper). The challenge with this is that the range of viewing distances for the typical video monitor is relatively limited. If you sit beyond the 30 degree mark (about 8 feet for a 60 inch diagonal display), you will begin to lose the detail. If you sit closer than about 3.75 feet you will begin to see pixels.
This becomes a significant challenge as shown in the next figure (click here for larger version). Here a typical 11x14 conference room with a video system is shown with the acceptable viewing distances for 4 sizes of monitors. Even with a table optimized for video, the issues of viewing range are clear. While the 65 and 70 inch monitors are best, both--especially the 70 inch--will have visible pixels for the closest viewers. And only the 70 inch delivers detail to the farthest participants.
One of the key reasons that telepresence rooms have better perceived experiences is that all of the viewers are typically located at a common distance from the displays as shown in the telepresence figure here (click here for larger version). As can be seen, a 65 inch monitor delivers ideal (40 degree) viewing in this type of system. By fixing the viewers to one side of a fixed distance table, the experience is optimized. However, this has two significant drawbacks: it limits the number of participants and imposes a relatively fixed nature on the space--i.e., it's not ideal for enabling non-video meetings in that room.
The potential of 4K in the video conferencing arena is shown in the figure (click here for larger version) that contrasts 2K and 4K video ranges. While the viewing angles do not change, the difference is that, just like in the theater, pixels will not be visible until the viewer gets half the distance closer to the screen. The smaller 60 degree angle illustrates this. So the short-distance viewing area is now extended 50% closer to the screen as shown in the right-hand blue box for the 4K display. Much like the vaunted "retinal displays" of tablets and smartphones, even sitting fairly close to the 4K monitor will not reveal pixels.
The last figure (click here for larger version) shows a comparison of 65-and 70-inch 2K and 4K displays in the same conference room shown in the 3rd figure. As can be seen, the 70 inch display provides the best overall viewing for almost all of the participants. The farthest participant is just beyond the 30 degree arc, and the closest participants will not see pixels. In fact, an 80-inch display would be ideal, but these are not yet common in video conferencing due to their high cost. The point is that for video conferencing, bigger displays are generally better, unless you are sitting too close. 4K displays solve that issue.
With the video display vendors moving to 4K, this is a real potential. Both Sony and JVC have shown 4K projectors that use interpolation to create a seamless 4K image from a 2K video stream. And Canon has announced a commercial 4K flat panel display for video mastering that is claimed to not be pixel-visible, regardless of distance. It is of relatively small size, only 30 inches, and more tuned to desktop use (the same issues apply for a large display at short viewing distances). LG has indicated they plan on introducing at least one 4K LCD/LED flat panel display late in 2012. With challenges in how to differentiate and compete in video displays becoming clear, 4K is probably the next frontier of competition.
As it is probable that the video conferencing stream will stay 2K due to bandwidth and the cost of codecs, the adoption of 4K displays will really just eliminate the pixel visibility for close viewers. However, this still would represent a significant impact on the perceived quality of the viewing experience in non-telepresence video conferencing rooms. For telepresence rooms with their fixed viewing distances, the 4K displays may be of little value.
