Clear-Vision

{{Short description|Japanese analogue widescreen television broadcasting system}}

Clear-Vision is a Japanese EDTV (Extended Definition TV){{cite web |last=FUKINUKI |first=Takahiko |title=EDTV |date=March 1991 |url=https://search.ieice.org/bin/summary.php?id=e74-b_3_540}}{{cite web |date=February 5, 1992 |title=HI-Vision TV is given a low survival rating |url=https://www.afr.com/politics/hi-vision-tv-is-given-a-low-survival-rating-19920205-k4t0m |website=Australian Financial Review}} television system introduced in the 1990s, that improves audio and video quality while remaining compatible with the existing broadcast standard.{{cite news |last=Pollack |first=Andrew |date=September 15, 1994 |title=Japanese Taking to Wide-Screen TV |work=The New York Times |url=https://www.nytimes.com/1994/09/15/business/japanese-taking-to-wide-screen-tv.html |via=NYTimes.com}} Developed to improve analog NTSC,{{cite book |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1118-1-199710-W!!PDF-E.pdf |title=Recommendation ITU-R BT.1118-1 - Enhanced compatible widescreen television based on conventional television systems |publisher=ITU |year=1997}} it adds features like progressive scan, ghost cancellation and widescreen image format. A similar system named PALplus was developed in Europe with the goal of improving analog PAL broadcasts.{{cite web |url=https://hartj.pages.iu.edu/documents/dtveurjpn_000.pdf |title=Digital Television in Europe and Japan}}

The initial version of the system was called IDTV (Improved Definition Television,{{cite book |url=https://ntrs.nasa.gov/api/citations/19920002007/downloads/19920002007.pdf |title=JTEC Panel Report on High Definition Systems In Japan |publisher=U.S. Department of Commerce |year=1991}} or SuperNTSC{{cite book |last=Gerbarg |first=Darcy |date=January 31, 1999 |title=The Economics, Technology and Content of Digital TV |url=https://books.google.com/books?id=jqQuDKkdhgwC&dq=Wide-aspect+Clear-vision&pg=PA303 |publisher=Springer Science & Business Media |isbn=9780792383253 |via=Google Books}}) and was based on advanced signal processing on TV receivers. This allowed improvements such as progressive scan, ghost cancellation (reducing the effects of multipath propagation) and NTSC luminance and chroma crosstalk reduction (by way of filtering), without requiring any extra information being broadcast. These early studies were done by NTV,{{cite web |title=Corporate History |url=https://www.ntv.co.jp/english/an/ch.html |website=NIPPON TV}} under the direction of the MPT (Ministry of Post and Telecommunications) and the BTA (Broadcasting Technology Association).

This early standard was published as ITU-R recommendation BT.797 - "CLEARVISION".{{cite book |url=https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1298-0-199710-W!!PDF-E.pdf |title=Recommendation ITU-R BT.1298 - Enhanced wide-screen NTSC TV transmission system |publisher=ITU |year=1997}} Public broadcasting began on NTV in August 1989, under the name of EDTV-I or "Clear-Vision", ending on July 24, 2011.

Tests for an updated system known as EDTV-II{{cite journal |last1=Nakayama |first1=K. |last2=Kojima |first2=T. |last3=Miyaguchi |first3=H. |last4=Sawaragi |first4=T. |last5=Yaguchi |first5=Y. |date=August 5, 1995 |title=EDTV-II decoder by SVP2 (the 2nd generation of scan-line video processor) |url=https://ieeexplore.ieee.org/document/468089 |journal=IEEE Transactions on Consumer Electronics |volume=41 |issue=3 |pages=634–642 |doi=10.1109/30.468089 |via=IEEE Xplore |url-access=subscription}}{{cite web |title=The Journal of the Institute of Television Engineers of Japan |url=https://www.jstage.jst.go.jp/browse/itej1978/49/9/_contents/-char/en |website=www.jstage.jst.go.jp}} or "Wide-aspect Clear-vision" started in 1994.{{cite web |title=EDTV2 試験放送 画質評価用スライド放送 |url=https://www.youtube.com/watch?v=K7hFBvAHFq8 |via=www.youtube.com}} EDTV-II supported 480p{{cite book |date=January 1, 1997 |chapter=525-line progressive scan signal digital interface standard and equipment |chapter-url=https://digital-library.theiet.org/content/conferences/10.1049/cp_19971258 |pages=141–146 |doi=10.1049/cp:19971258 |via=digital-library.theiet.org|title=International Broadcasting Conference (IBC) |last1=Hori |first1=A. |volume=1997 |isbn=0-85296-694-6}} progressive scan,{{cite book |last=Noble |first=Gregory W. |date=September 5, 2018 |title=Collective Action in East Asia: How Ruling Parties Shape Industrial Policy |url=https://books.google.com/books?id=ZlpuDwAAQBAJ&dq=Wide-aspect+Clear-vision&pg=PA110 |publisher=Cornell University Press |isbn=9781501732034 |via=Google Books}} wide-screen{{cite journal |url=https://cir.nii.ac.jp/crid/1390282680042730624 |title=方式の標準化と審議経過 |first1=菊池 |last1=紳一 |first2=羽鳥 |last2=光俊 |date=July 9, 1995 |journal=テレビジョン学会誌 |volume=49 |issue=9 |pages=1117–1120 |via=cir-nii-ac-jp.translate.goog |doi=10.3169/itej1978.49.1117 |doi-access=free |url-access=subscription}} and digital audio. Public broadcasting began in July 1995 by NTV.{{cite web |title=Telecompaper |url=https://www.telecompaper.com/news/matsushita-firms-develop-edtv-camera--15229 |website=www.telecompaper.com}}{{cite journal |last=Masataka |first=Takahashi |date=July 5, 1996 |title=The Broadcasting Operation Of EDTV-II (Vide Clear Vision) Programs Especially Master Control Room |url=https://cir.nii.ac.jp/crid/1390001204521430144 |journal=ITE Technical Report |volume=20 |issue=3 |pages=41–45 |doi=10.11485/tvtr.20.3_41 |via=cir.nii.ac.jp}} The standard was published as ARIB STD-B9 - "Direct Coding for EDTV-II Television Signal" in 1997{{cite web |title=About obtaining ARIB Standards (STD-B9)｜Association of Radio Industries and Businesses |url=https://www.arib.or.jp/english/std_tr/broadcasting/std-b9.html |website=www.arib.or.jp}} and as ITU BT.1298 - "Enhanced wide-screen NTSC TV transmission system".

EDTV-II broadcasts are displayed in letterbox format (with black bands on the top and bottom of the screen) on regular 4:3 NTSC 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.{{cite book |last1=Suzuki |first1=N. |last2=Fukinuki |first2=T. |last3=Kageyama |first3=M. |last4=Ishikura |first4=K. |last5=Yoshigi |first5=H. |title=International Broadcasting Convention - IBC '94 |date=January 1, 1994 |chapter=Multiplexing scheme of helper signals on bars in EDTV-II |volume=1994 |chapter-url=https://digital-library.theiet.org/content/conferences/10.1049/cp_19940723 |pages=32–36 |doi=10.1049/cp:19940723 |doi-broken-date=7 December 2024 |via=digital-library.theiet.org}} This solution is similar to the one used on PALplus,{{cite book |last1=Mertzios |first1=B. G. |last2=Liatsis |first2=P. |date=November 8, 1996 |title=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 |url=https://books.google.com/books?id=qVun--RUP0UC&dq=EDTV-II+japan&pg=PA456 |publisher=Elsevier |isbn=9780080539768 |via=Google Books}} 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.

When introduced, EDTV-II was used on many shows by NTV such as Friday Road Show.{{cite web |url=https://ja.wikipedia.org/wiki/%E3%83%AF%E3%82%A4%E3%83%89%E3%82%AF%E3%83%AA%E3%82%A2%E3%83%93%E3%82%B8%E3%83%A7%E3%83%B3 |title=ワイドクリアビジョン - Wikipedia |website=ja.wikipedia.org}}{{Circular reference|date=September 2023}} At the time of TOKYO MX{{cite web |url=https://www.nicovideo.jp/watch/sm27191806 |title=TOKYO MX 開局の瞬間（199511） |date=September 20, 2015 |via=www.nicovideo.jp}} start in 1995, more than half of its broadcasts were in widescreen using EDTV-II, such as Tokyo NEWS. Interest was predicted to be high, with manufacturers such as Sony and Mitsubishi having 16 to 32 widescreen EDTV-II compatible TVs available that same year.{{cite book |url=https://www.sony.com/en/SonyInfo/IR/library/ar/ar_sony_1995.pdf |title=Annual Report 1995 |publisher=SONY |pages=16}}{{cite web |url=https://www.youtube.com/watch?v=Y5MZvIFC6Y4 |title=1995年懐かCM【三菱電機】 |via=www.youtube.com}} Yet, due to lack consumer interest, broadcasts returned to regular 4:3 over the years. NHK used the system occasionally, as it was more interested in promoting its own analog high-definition MUSE system. Widescreen EDTV-II broadcasts gradually disappeared, with World Heritage'', broadcast by Sony, being the last show shown using the format.{{cite journal |url=http://www.asahi.com/articles/ASH484Q33H48ULFA015.html |title=ソニー、TBS「世界遺産」スポンサー撤退 番組は継続 |date=April 9, 2015 |journal=朝日新聞}}

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.{{cite book |last=Hart |first=Jeffrey A. |date=February 5, 2004 |title=Technology, Television, and Competition: The Politics of Digital TV |url=https://books.google.com/books?id=R4j_Pmj_l9MC&dq=Wide-aspect+Clear-vision&pg=PA197 |publisher=Cambridge University Press |isbn=9781139442244 |via=Google Books}} The system was replaced by ISDB digital broadcasts after 2012.