3-D Cinema Becomes More Realistic

Experts and analysts have unanimously declared 3-D as the top emerging technology. Developments in 3-D projection technology and invention of DLP cinema technology have brought about a revolutionary change in 3-D user experience.


I remember after a long wait of nearly three weeks, I finally managed to get  the tickets for Hollywood 3-D flick Avatar. Avatar has certainly marked the beginning of the 3-D era. Technology becomes more acceptable when people start to understand  it. I too wanted to know how is it possible to be present in the scene with the Navis on the Padora moon when I was not there for the shooting!

"3-D  has  finally  come  to  live through Avatar," feels S. Ganesh, business development manager, DLP products, Texas Instruments. The advent of new technology to capture and project 3-D has enhanced user acceptance and experience. "New technologies have made 3-D presentation more realistic with natural look and feel," adds Ganesh.

Senthil  Kumar,  director  and  co- founder,  Real  Images,  says, "3-D is the  technology  of  this  decade.  As  it comes  to  theatre,  people  want  it  at their  homes  too.  But  for  anything  to happen  on  the  small  screen,  it  has  to first happen and be successful on the big screen."

The advancement in micro-mirror technology and  fast responsive software to play 3-D video has certainly enhanced 3-D user experience.  You can  watch  3-D  without  eye-fatigue or  headache,  which  was  not  possible earlier. "The technology of playing the 3-D  content  is  almost  perfect  today," claims Senthil.

3-D projection technologies
The  3-D  projection  technology  was introduced  way  back  in  1950s.  But the process of setting up two cameras projecting on the same screen was extremely  tedious  and  synchronisation was  a  big  problem.  Advancement in  presentation  technology  with  the help of digital projection has elevated stereoscopic  3-D  to  a  quality  of  user experience for the first time.

There  are  many  technologies  to create and view 3-D images, primarily based  on  how  each  eye  receives the image  by  variable-intensity  light  and how the brain processes and combines the information to perceive the third-dimension depth.

"The  most  commonly  deployed technologies  in  Indian  theatres  for 3-D  are  the  dual projector technology,  colour wheel  technology  and XpanD technology," informs Amitabh Vardhan, CEO, PVR Cinemas. All the technologies  basically  project  the  3-D content  containing  left-eye  and  right-eye  images  on  the  same  screen. You need  to  wear  glasses  to  separate  the left- and  right-eye  view  just the way it's done naturally.

"In  dual  projector  set-up,  we have two digital projectors: one gives the  left-eye  view  and  the  other  the right-eye  view,"  shares  Rajiv  Kumar, regional  manager  (engineering),  PVR Cinemas.  Each projector  is  connected to the playback server and receives the data through BNC (Bayonet Neill-Con- celman) cable at the rate of 24 frames per  second  (fps).  "Each  projector  has a  separate  filter  that  polarises  the light  and  the  eye-glass  has  the  corresponding filter for each eye," explains Senthil. This  is a  stable  arrangement, suitable  for  big-screen  theatres  and auditoria.

Another  3-D  technology  based on polarisation is the colour wheel. It requires a single projector. "A colour/ filter wheel placed in front of the projector spins at the rate of 4320 rotations per minute (rpm)," shares Senthil. The technology  patented  by  MasterImage 3-D uses a high-efficiency circular polarisation  filter to separate the left and right images.

"Both  the  dual  projector  and  colour  wheel  technologies  require  silver screen  or  ZScreen--a  high-definition (HD)  screen  that  preserves  the  light and  doesn't  dissipate  it," says  Vardhan. "Regular screen cannot preserve the  light  polarisation  that  is  used  by both  the  technologies," adds  Senthil. The screen is a mirrored surface, silver in colour, hence the name silver screen.

Single-projector-based XpanD technology  is  apparently  the  most easy  for  2-D  to  3-D  transition.  The benefit  of  this  technology  is  that  it does not require a silver screen. This greatly  saves  the  cost  involved  in second projector or the silver screen. However, you need active filter glasses with electronics to view the image. There are infrared (IR) emitters in the auditoria that  are  synchronised  with the  active  left  and  right  eye-glasses to  open  and  shut  them  (glasses)  alternately When  a  left-eye  image  is projected,  the  infrared  emitter  sends a signal to open the left-side glass and shut the right and vice-versa.

In terms  of  quality  and  performance, all the technologies are almost equal.  "We  have  experimented  and found that with the same intensity of digital projector, the dual projector and colour  wheel  technologies  are  more suitable for big theatres and auditoria than the XpanD, which works well in small areas. So we have implemented XpanD in the PVR Gold," inform Rajiv and team from PVR.

Digital projectors
"Digital  light  processing  (DLP)  has  a predominant  market  share  in  projection technology for 3-D cinema," says Ganesh. Its slight variant DLP cinema technology adheres to the Digital Cinema Initiatives (DCI) standards laid by a team of Hollywood studios. The DCI standards  were  introduced  to  ensure that  the  quality  is  not  compromised while transitioning to digital.

The  DLP  technology  from  Texas Instruments  can  project  3-D  images using a single projector. TI's DLP chip is  used  in  digital  projectors.  "Marco, NEC and Christie  are  the  leading manufacturers of DLP cinema projectors," shares Ganesh.

Explaining the technology, Ganesh says, "DLP is an optical semiconductor  that  has  millions  of  tiny  mirror particles.  It  is  called  DLP  or  DMD (digital micro-mirror device). This optical semiconductor manipulates light using  images  that  are  sent  out  from the  server  and  the  image  is  formed on  the  screen."  The  tiny  mirrors  are individually  controllable  and  move extremely  fast.  When  the  coloured light  falls  on  this  chip,  the  image  is generated on the chip and magnified using  optical  components  to  project on the large screen.

Texas Instruments offers two chipsets with different resolutions, 2K and  4K.  "2K  chip  is  used  for  screens normally  up  to  21.33m  (70-feet)  size and 4K does well  for  screens  up  to 30.48m (100-feet) wide," says Ganesh. "Around 14,000 cinema theatres have adopted  DLP  technology  worldwide, out  of  which  7000  are  3-D-enabled. Out  of  14,000,  approximately  200  are in  India,  and  nearly  50  of  them  are 3-D-enabled."

Cinema playback servers
In  digital  cinema,  you  need  a  digital playback  server  to  play  the  digital video file. "Digital cinema server is a computer, essentially a  secured  play- back  device,"  explains  Senthil.  The digital  movie  is  loaded  on  the  server for playback.

When  you  get  the  digital  movie file in DCI-compliant J2K format, the server first loads the file on its internal storage.  While  playing,  it  decrypts the movie as the file is encrypted. "It puts  the  water  mark  (date  and  time) on  the  movie  and  then  encrypts  it back. The encrypted signal is sent to the projector over a serial link called high-definition  serial  data  interface (HDSDI),"  says  Senthil.  Unless  the projector  knows  decryption  keys, which  are  sent  over  Ethernet,  it  will not be able to decrypt the video. This protects against piracy.

QubeXP-D from Qube is one of the commonly used servers. It is based on Microsoft's Windows XP -- a modular embedded operating system -- to maximise reliability and security. The server can be managed and operated locally or remotely via a powerful, highly interactive Web-based user interface. "We configure the channels to play either 2-D or 3-D content," explains Rajiv. Doremi is another popular vendor of playback servers in India.

3-D digital format
The fundamental working principle of 3-D is projecting left and right eyeview separately. As the 3-D movie carries the information of both images (left- and right-view), the 3-D file is almost double the size of 2-D file. Digital movie files come in DCI JPEG 2000 (J2K) file format created by Joint Photographic Experts Group. J2K supports a very high resolution and flexibility of decoding algorithms and scalability. Earlier, MPEG file format was used and even today some of the films come in MPEG format.

"MPEG file for a 2-D version takes up to 80GB space, while J2K occupies up to 190-220 GB," shares Vardhan. Digital 3-D content is distributed in 48fps format.

3-D glasses

The 'D' and 'E' of cinema In digital 2-D cinema, there are two variants, D-cinema and E-cinema. For D-cinema, projectors and servers need to be DCI-compliant. To run a Hollywood movie, you have to satisfy this requirement. Also, currently for 3-D, you need the D-cinema set-up. E-cinema is an initiative of the Indian film makers to release the Indian movies digitally. "For a drop of around 10 per cent in quality, we have huge price reduction in the E-cinema," explains Senthil. QubeXP-E is used for digital 2-D E-cinema. "The projectors use the DLP technology (not the DLP cinema technology) but do not adhere to DCI standards," adds Ganesh. These aren't 3-D-ready.

The perception of depth is possible only when you view the left- and right-eye images differently. All the 3-D technologies discussed so far work on the same principle. The passive polarisation technology used in dual projectors and colour wheel uses a passive glass filter. It uses polarised lenses for each eye and makes it possible to receive the images separately. RealD is the market leader in these types of glasses. MasterImage 3-D too uses a similar technology.

You need to wear active glasses to view 3-D in XpanD technology. "The active glasses are called active because these have active electronics consisting of IR receiver and the battery," explains Ganesh. "The glass is a thinfilm transistor liquid-crystal display (TFT LCD) that opens and shuts the LCD shutter for each eye in sync with the left and right projection so each eye sees the appropriate frame of the image."

Talking about the cost, Ganesh said that the passive glasses cost around 40-50 cents, whereas active glasses cost around $50. Passive glasses are one-time-use, while active glasses can be cleaned and used again. "Till now, there is no technology that supports 3-D viewing without wearing glasses in theatres," says Ganesh. Many shopping malls, however, are showing 3-D without glasses, which has some sort of grids visible.

3-D cinema ecosystem
The 3-D ecosystem is the combination of technology and content. The technology has almost reached a sophisticated level, but the content is still in infancy. "Creating 3-D content is a major challenge," exclaims Senthil. "Just like the move from B&W to colour, a move is required for cinematographers, editors and directors to understand the rules of 3-D and what makes it interesting to the audience." Highly responsive image processing software are required to create 3-D content.

Animation and live-action content will hit the market first. "Some of the older classics like Titanic are already in process to be released in 3-D," claims Senthil. "We received a very good response for 3-D Avatar and we expect a lot more titles to be released in 3-D this year. Some Indian movies too are expected to hit the market in 3-D by the end of the year," informs Vardhan.