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Clear-Vision

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Clear-Visionis a Japanese EDTV (Extended Definition TV)[1][2]television system introduced in the 1990s, that improves audio and video quality while remaining compatible with the existing broadcast standard.[1][3]Developed to improveanalog NTSC,[4]it adds features likeprogressive scan,ghost cancellationandwidescreenimage format. A similar system namedPALPluswas develop in Europe with the goal of improvinganalog PALbroadcasts.[5]

The initial version of the system was calledIDTV[5](Improved Definition Television,[6]or SuperNTSC[7]) and was based on advanced signal processing on TV receivers. This allowed improvements such as progressive scan, ghost cancellation (reducing the effects ofmultipath propagation) and NTSCluminance and chroma crosstalkreduction (by way of filtering),[6]without requiring any extra information being broadcast. These early studies were done byNTV,[8]under the direction of the MPT (Ministry of Post and Telecommunications) and the BTA (Broadcasting Technology Association).[1][5]

This early standard was published asITU-R recommendation BT.797 - "CLEARVISION".[9]Public broadcasting began on NTV in August 1989, under the name ofEDTV-Ior "Clear-Vision",[8][1][5]ending on July 24, 2011.

Tests for an updated system known asEDTV-II[10][11]or "Wide-aspect Clear-vision"[1][3]started in 1994.[12]EDTV-II supported480p[13]progressive scan,[14]wide-screen[15]anddigital audio.Public broadcasting began in July 1995 byNTV.[8][16][17][5][2]The standard was published asARIBSTD-B9 - "Direct Coding for EDTV-II Television Signal" in 1997[18]and as ITU BT.1298 - "Enhanced wide-screen NTSC TV transmission system".[9]

EDTV-II broadcasts are displayed inletterboxformat (with black bands on the top and bottom of the screen)[14]on regular4:3NTSC receivers with no decoding ability. Information to reconstruct the original image signal is transmitted as helper signals - HH (horizontal high), VH (vertical high) and VT (vertical-temporal) - placed on the black bars.[19][9]This solution is similar to the one used on PALplus,[20]a comparable system to improve analog PAL broadcasts. On compatible TV sets, broadcasts are seen in 16:9 wide-screen retaining the full original 480 line resolution.[9]

When introduced, EDTV-II was used on many shows by NTV such asFriday Road Show.[21][circular reference]At the time ofTOKYO MX[22]start in 1995, more than half of its broadcasts were in widescreen using EDTV-II, such asTokyo NEWS.[21]Interest was predicted to be high, with manufacturers such asSonyandMitsubishihaving 16 to 32'' widescreen EDTV-II compatible TVs available that same year.[23][24]Yet, due to lack consumer interest, broadcasts returned to regular 4:3 over the years.NHKused the system occasionally, as it was more interested in promoting its own analog high-definitionMUSEsystem.[21]Widescreen EDTV-II broadcasts gradually disappeared, withWorld Heritage,broadcast bySony,being the last show shown using the format.[25]

Other than widescreen broadcasts, the system gave a limited improvement in image quality, mostly noticeable on larger TV sets. Yet these TVs benefited more from true HDTV broadcasts using the MUSE system, also available at the time.[5][26]The system was replaced byISDBdigital broadcastsafter 2012.

Technical details[edit]

The EDTV-II "Clear-Vision" transmission system is based on the following elements:[9][27]

  • Vertical conversion of the original full resolution 480 lines widescreen image to a 360-line 16:9 letterbox picture.Highandlow-passfilters are used.
  • Recovery of original vertical image resolution using helper signals (VH, VT). Taking advantage of the letterbox black bands, these are modulated on thecolor subcarrier,with visibility minimized on regular 4:3 televisions. The vertical helper (VH) carries the missing verticalluminancedetails in motionless portions of the picture. The vertical temporal helper (VT) carries information allowing the receiver to reconstruct the original progressive scanning.
  • Recovery of original horizontal image resolution using a helper signal (HH), taking advantage of the “Fukinuki hole”. Horizontal luminance between 4.2 - 6 MHz is transmitted by frequency divisionmultiple xinginto the active area of the letterbox signal.
  • Awide-screen signalingsystem, according to recommendationsEIAJCPX1204 / ITU BT.1119;[28]
  • Thechrominancesignal is transmitted in the active area of the letterbox (360 lines).

Some elements are optional, but the standard requires that at least one helper and the wide-screen signaling are used.[9]

EDTV-II "Clear-Vision" technical details[20][19][29]
Aspect Ratio 16:9 letterbox
Active area 360 lines
Black area 120 lines
Horizonal Resolution 0 - 4.2 MHz
Vertical Resolution 0 - 360 lines/height
Vertical High Resolution Helper (VH) 360 - 480 lines/height
Vertical-Temporal Helper (VT) 180 - 360 lines/height
Horizontal Helper (HH) 4.2 - 6.0 MHz
Scanning 576 lines progressive / interlaced

See also[edit]

References[edit]

  1. ^abcdeFUKINUKI, Takahiko (March 1991)."EDTV".
  2. ^ab"HI-Vision TV is given a low survival rating".Australian Financial Review.February 5, 1992.
  3. ^abPollack, Andrew (September 15, 1994)."Japanese Taking to Wide-Screen TV".The New York Times– via NYTimes.
  4. ^Recommendation ITU-R BT.1118-1 - Enhanced compatible widescreen television based on conventional television systems(PDF).ITU. 1997.
  5. ^abcdef"Digital Television in Europe and Japan"(PDF).
  6. ^abJTEC Panel Report on High Definition Systems In Japan(PDF).U.S. Department of Commerce. 1991.
  7. ^Gerbarg, Darcy (January 31, 1999).The Economics, Technology and Content of Digital TV.Springer Science & Business Media.ISBN9780792383253– via Google Books.
  8. ^abc"Corporate History".NIPPON TV.
  9. ^abcdefRecommendation ITU-R BT.1298 - Enhanced wide-screen NTSC TV transmission system(PDF).ITU. 1997.
  10. ^Nakayama, K.; Kojima, T.; Miyaguchi, H.; Sawaragi, T.; Yaguchi, Y. (August 5, 1995)."EDTV-II decoder by SVP2 (the 2nd generation of scan-line video processor)".IEEE Transactions on Consumer Electronics.41(3): 634–642.doi:10.1109/30.468089– via IEEE Xplore.
  11. ^"The Journal of the Institute of Television Engineers of Japan".jstage.jst.go.jp.
  12. ^"EDTV2 thí nghiệm truyền họa chất bình 価 dùng スライド truyền"– via youtube.
  13. ^Hori, A. (January 1, 1997)."525-line progressive scan signal digital interface standard and equipment".International Broadcasting Conference (IBC).Vol. 1997. pp. 141–146.doi:10.1049/cp:19971258.ISBN0-85296-694-6– via digital-library.theiet.org.
  14. ^abNoble, Gregory W. (September 5, 2018).Collective Action in East Asia: How Ruling Parties Shape Industrial Policy.Cornell University Press.ISBN9781501732034– via Google Books.
  15. ^Thân một, cúc trì; quang tuấn, vũ điểu (July 9, 1995)."Phương thức の chuẩn hoá と xem xét kinh quá".テレビジョン học được chí.49(9): 1117–1120.doi:10.3169/itej1978.49.1117– via cir-nii-ac-jp.translate.goog.
  16. ^"Telecompaper".telecompaper.
  17. ^Masataka, Takahashi (July 5, 1996)."The Broadcasting Operation Of EDTV-II (Vide Clear Vision) Programs Especially Master Control Room".ITE Technical Report.20(3): 41–45.doi:10.11485/tvtr.20.3_41– via cir.nii.ac.jp.
  18. ^"About obtaining ARIB Standards (STD-B9)｜Association of Radio Industries and Businesses".arib.or.jp.
  19. ^abSuzuki, N.; Fukinuki, T.; Kageyama, M.; Ishikura, K.; Yoshigi, H. (January 1, 1994)."Multiple xing scheme of helper signals on bars in EDTV-II".International Broadcasting Convention - IBC '94.Vol. 1994. pp. 32–36.doi:10.1049/cp:19940723– via digital-library.theiet.org.
  20. ^abMertzios, B. G.; Liatsis, P. (November 8, 1996).Proceedings IWISP '96, 4–7 November 1996; Manchester, UK: Third International Workshop on Image and Signal Processing on the Theme of Advances in Computational Intelligence.Elsevier.ISBN9780080539768– via Google Books.
  21. ^abc"ワイドクリアビジョン - Wikipedia".ja.wikipedia.org.
  22. ^"TOKYO MX khai cục の nháy mắt ( 199511 )".September 20, 2015 – via nicovideo.jp.
  23. ^Annual Report 1995(PDF).SONY. p. 16.
  24. ^"1995 năm hoài かCM【 tam lăng điện cơ 】"– via youtube.
  25. ^"ソニー, TBS “Thế giới di sản” スポンサー lui lại phiên tổ は継続 ".Mặt trời mới mọc tin tức.April 9, 2015.
  26. ^Hart, Jeffrey A. (February 5, 2004).Technology, Television, and Competition: The Politics of Digital TV.Cambridge University Press.ISBN9781139442244– via Google Books.
  27. ^Kageyama, Masahiro (2010).Thesis Research on high image quality and high functionality of television(PDF).
  28. ^CS4954/55 NTSC/PAL Digital Video Encoder(PDF).Cirrus Logic, Inc. 2006.
  29. ^Multiple xing Scheme for Helper Signals in Top and Bottom Bars in EDTV-II.Journal of the Institute of Television Engineers of Japan. 1994.
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