Tuesday 24 July 2012

Super Hi-Vision

         British Broadcasting Corporation will test broadcast London 2012 Olympics footages in the latest Super Hi-vision (SHV) television format. This format has 16 times the resolution of the existing High Definition TV format and with 22.2 multichannel surround sound. This provides a amazing picture quality and viewers feel a strong sense of reality. One can watch Olympics in Super Hi-vision theaters in  BBC Broadcasting House in London , BBC Pacific Quay in Glasgow and  National Media Museum, in Bradford.  SHV was developed by NHK (Nippon Hōsō Kyōkai) in English it is Japan Broadcasting corporation.


This ultra high definition televsion format has 4000 scanning lines and it contains 7680x4320 pixels per frame. SHV camera uses 8 megapixel CCD camera. It uses four channels Green1, Green2, Red, Blue, instead of traditional Red, Green, Blue channels. Thus around 32 mega pixel data is generated for every frame. It uses MPEG-2 video compression format with 4:2:2 sampling format. AVC/H.264 codec are reconfigured to transport SHV signals to mobile devices. SHV has a angular resolution 40 to 50 degrees, which gives the sense of realness. It has 60 frames per second instead of the conventional 25 frames in PAL and 30 frames in American NTSC colour system.

It needs 24 speakers to create a 3D spatial impression to the viewers. This helps to augment the sense of reality. It has 9 speakers in upper layer frequency, 10 speakers for middle layer frequency, three speakers in lower layer frequency and at last two speakers for  low frequency effect . It uses 48 KHz sampling rate, 24 bit Pulse Code Modulation which results in 28 Mbps or Dolby-E systems having 7 Mbps.

Researchers at NHK used to phychological methods to figure out the relationship between sense of reality verses the viewing angle. They found  higher the viewing angle more the feel the reality. Viewing angle below 40 fail to provide any reality feel. From 40 to 80 sense of reality increases with the viewing angle. Increase in viewing angle beyond 80, do not dramatically increase the 'feel'.

In 1953 televisions had a screen size was 12 inch.  Fourteen inch colour  TV's  emerged after 1960. Size grew to 20 inch in 1975 and it reached 29 inch in 1990. Beyond this size conventional Cathode Ray Tube (CRT) cannot be manufactured. So 50 inch LCD or LED Flat screens were developed in 2006. Viewing distance and resolution has a direct relationship. Optimal viewing distance of conventional TVs are four to six times the diagonal of the TV. For a TV having a diagonal size of 21 inch, needs a viewing distance of seven feet.  Thus size of the room limits the size of TV screen.  So it becomes necessary to increase resolution to have bigger screens at home.

An uncompressed SHV signals require around 50 Gbps and with digital compression bit rate requirement will be between 200 Mbps to 400 Mbps.The present 12 GHz systems can handle upto 52 Mbps. So they move to 21GHz range of frequency (21.4 GHz-22.0 GHz). But at this frequency rain act as a spoilsport. Non-real time broadcasting is used to combat rain attenuation effects.

 Khushu National Mueseum's  SHV theater was inaugurated in October 2005.  This  is the first time  SHV  system was deployed for public use.

SOURCE:
  • Steps Towards the Practical use of Super Hi-vision by M. Maeda et al from NHK Science and technical Research laboratories.
  • "Super Hi-Vision -  research on future ultra HDTV system", article by Masayuki Sugawara, NHK, EBU Technical Reveiw - 2008 Q2
  • S.Sakaida, N. Nakajima, A. Ichigaya, and M. Kurozumi, "The Super Hi-Vision Codec," Proceedings of ICIP 2007, pp. 21-24.
  • Transmission Techniques for Broadcast Satellites in the 21-GHz Band aiming for "Super Hi-Vision" Broadcasting, Broadcast Technology No.24, Autumn 2005 pp 8--13
  • http://www.bbc.co.uk/blogs/bbcinternet/2012/07/super_hi_vision_ultra_hd.html

Saturday 14 July 2012

Embedded Vision Systems

       Microsoft Kinect product is used as  novel input interface for 'XboX 360' game console.  Kinect is a perfect example for embedded vision system. Eight million Kinect sold, just within two months of the launch. It shows the  power of embedded vision system.
     Embedded Vision can be defined as a microcontroller based system that incorporate vision sensor (ex. camera) and able to understand the environment through the sensor. Digital camera is a microcontroller based system that contain vision sensor . Outcome of digital camera will be pictures. But camera is incapable of interpret the pictures it took. So digital camera is NOT a embedded vision system. System on Chip (SoC), Graphical Processing Unit(GPU) , Digital Signal Processor(DSP) and Field Programmable Gate Array (FPGA) can be used in place of Microcontrollers. General purpose personal computer strictly No-No. Smart phones, tablet computers and surveillance system can be upgraded to embedded vision system.
Applications:
  • To find a child that is struggling in swimming pool.
  • To find intruder(s)
  • To detect whether lane change has occurred  or not and if occurred then warn driver of automobile.
Embedded vision system will carry out following three functions
1. Image acquisition and optimization
  •  Noise reduction, image stabilization and colour space correction
  • Outcome of optimization stage, need not be aesthetically pleasing pictures but they should be easily processable by further stages.
2.  Building objects through pixels
  •  First level operations used are  Image  filtering, Haar filters, Edge detection, Histogram, Optical flow, Erosion and dilation, Thresholding.
  • Second level operations used are Connected component labelling, contour tracing, clustering and hough transform

     3. Object analysis and interpretation
    • object movement tracking, classification, obstacle detection
    • Kalman filters as predictive filters, hidden markov models correlation, finite state models, neural networks All the above operations are  computation intensive. Extensive DSP algorithms are also used.                                                                                                                                                         
    Embedded Vision Alliance  is a organisation that look into every aspect of embedded vision.  It's website address is  http://www.embeddedvision.com/ . In the website go to 'Industry analysis' in that go to 'Market Analysis'. This section seems to be very informative. 'News' section gives a reasonable  amount of information.  'Technical Articles' section needs registration. Most of the website content, directs us where information available than providing them. There are no advertisement section. Website has professional look. It is worth visiting the site.

     The following link gives how much importance IEEE gives embedded vision technology.
    A note on DSP
    linear filtering is an convolution operation. After the advent of Fast Fourier Transform (FFT) it became desirable to transform the signal into frequency domain and multiply with desired frequency response (In time domain it is called impulse response)  and transform back the resultant signal in time domain. If it is a image signal will be transformed to spatial-frequency domain and after multiplication, resultant image will be converted back to spatial domain.  FFT was proposed by Coolie and Tukey in 1965. It was too mathematical. In 1967 Tom Stockham and Charlie Rader gave flow graph representation for FFT. I thing it is called 'Butterfly diagram' nowadays. 
    Courtesy:
    • Eye Robot: embedded vision the next big thing in DSP, by Brian Dipert and Amit  Shoham,  IEEE  Solid State Circuits Magazine,  Vol. 4, No. 2, Spring 2012. [doi : 10.1109/MSSC.2012.2193077]
    • A note on DSP from the above magazine issue page number 36
    • Special thanks to Mr. B. Srinath

    Monday 2 July 2012

    Machine Vision Magazines

    I searched a lot and found out that only three machine vision magazines are available.

    1. Vision Systems Design



    • Magazine articles are crisp in nature
    • "White paper" section needs registration.
    • Back volumes are available from  September 1996.
    • If we register ourselves then we can get the Digital/Print issue free of cost. Registration process seems to less cumbersome.


     Link: http://www.vision-systems.com/index.html

    2. Imaging and Machine Vision Europe 

     

    • From the home page go to "feature" section (http://www.imveurope.com/features/)   to find back  volumes. They are available from April 2006 onwards. It is an bimonthly (once in two months).
    • Sections like 'Webcast' and "white paper" need registration.
    • The layout is good. 
    • Articles are little bit lengthy.
    Link : http://www.imveurope.com/

    3. Inspect 

    • Without registration, I was able to download PDF files from 'White paper' section .  I have to register myself to get the same content from other magazines.
    • Publication  started from 2009 onwards.
    • It is bimonthy magazine with an additional special issue magazine. So totally seven issues per year. It costs around 54 euro per year subscription.
    • It is available in English as well as German. It is published by Wiley & Sons .
    • They have a print circulation of 20000. Germany consumes 70% of the printed copies.
    • Looking into the archives, need registration. I thing one get a PDF version of the book after registration.The registration is very simple. It asks for your name, a password and CAPTCHA to ensure registration done by humans only. 
    • Archives are from year  2009 onwards. Year 2011 is not available. Why?