Talk:Rec. 709

The BT

What to the letters "BT" stand for in the "recommendation"?

Broadcast, Television Cxw (talk) 20:01, 29 April 2010 (UTC)[reply]

It means Broadcasting service (television). 2A00:1370:812D:178D:E8D7:9054:9DC5:E243 (talk) 15:43, 9 April 2021 (UTC)[reply]

I'm thinking of moving (renaming) this page to BT.709. "Rec." is the historical prefix, from the days when the organization was CCIR (dealing with radio). CCIR and CCITT (which had its own Recs.) were incorporated into ITU. However, there are other "Recs." from ITU, such as ITU-T G.709. The cover page of the document itself reads "Recommendation ITU-R BT.709-5," so the Rec. and the 709 aren't contiguous. It seems to me that BT.709 is relatively unambiguous, and it matches the notation in the standard itself. Also, I propose the same treatment for Rec. 601. Comments? (talk) 20:29, 2 March 2012 (UTC-5)

HD SD convert

"Whenever SDTV is upconverted to HDTV, or HDTV is downconverted to SDTV, at the studio or at the consumers' premises, luma-chroma matrixing is required."

Quote:"The colours produced by red, green and blue signals, with each of the others turned off, should be within the EBU tolerance boxes in EBU Tech 3273 [13]. The difference between the gamuts of ITU-R BT.709 [2] (HDTV) and EBU (SDTV) [14] systems is so small as to be negligible." Source:EBU – TECH 3321

So I delete the Part. --88.78.4.253 (talk) 15:55, 3 June 2012 (UTC)[reply]

The above statements are both correct, the EBU one refers to colour correction matrixing (also known as masking)and the second one luma matrixing to convert Rec 709 to Rec 601 signals, two entirely separate operations, so your stupid deletion was nothing short of ignorant vandalism. You should not edit things about which you clearly understand absolutely nothing. — Preceding unsigned comment added by 92.237.213.154 (talk) 00:06, 20 March 2014 (UTC)[reply]

Also, if we are talking about NTSC 1953, it is not: color managment is not negligable. And for SMPTE C technically too. See: http://drag.wootest.net/misc/palgen.html 2A00:1370:812D:F205:7520:9495:D4E5:3C4B (talk) 23:08, 28 April 2021 (UTC)[reply]

approved in 1990 Earliest revision

The article says that 709 was first approved in 1990. However, 709-1, which is the first revision listed, is dated 11/93. I'm not completely sure what's going on here, but this is at least unclear - can anyone help clear this up? — Preceding unsigned comment added by 80.229.27.22 (talk) 15:36, 14 March 2017 (UTC)[reply]

The first Rec709 in 1990 was under the CCIR which was superseded in 1992 by ITU, which published BT.709-1 in November of 1993. These early published recommendations still had a number of unanswered questions, it wasn't till BT.709-3 circa 2000-ish that the standard looks mostly as it does today. I'll put this into a revised history to clear things up. --Myndex (talk) 13:46, 10 December 2020 (UTC)[reply]

Caption for figure of primaries on chromaticity diagram

The caption of the first figure, depicting the BT.709 primaries on the CIE 1931 x, y chromaticity diagram has numerous issues:

The current label refers to the "CIE 1931 color space;" the figure depicts the CIE 1931 x, y chromaticity diagram.
The current label incorrectly asserts the figure "shows the Rec. 709 (HDTV) color space".
Verbiage "in the triangle" is awkward.

Accordingly, I have edited the caption to remove the errors of fact and improve readability. Lovibond (talk) 23:44, 17 August 2017 (UTC)[reply]

Major edit on Dec. 10 2020

In looking at this article, and the talk page here, it became clear the article had never been updated to reflect the changes in BT.709-6. In addition, the article had gathered a lot os, eh, dust, errors, and even some unsupported/unreliable opinion. Did my best to bring it all into Wikipedia standards, and hopefully did not miss anything, I mainly targeted the "big chunks" and went for clarity. I'm certainly happy to discuss further if anyone has questions or comments. For background, I'm a professional in the Hollywood film and television industry, and this is a subject I am very familiar with.

Some things to do still: put the frame rates into a table, perhaps gamut comparisons with other formats, gamut mapping, the use as the canonical set of primaries for unbound formats like EXR, etc etc. --Myndex (talk) 18:21, 10 December 2020 (UTC)[reply]

And to ADD: I just saw that my note on what was changed did not post with the change in history ?!? Weird. Might have been due to using the visual editor. --Myndex (talk) 18:27, 10 December 2020 (UTC)[reply]

Does anybody have CCIR Rec. XA/11 1986-90f, a.k.a. IWP 11/6-2108 (Canada)?

It derived BT.709 primaries. By B. Powell. Also there is some paper from him: "Influence of display primaries on the colorimetric characteristics of colour television", that is by Australian broadcasting corporation, report No 136. 2A00:1370:812D:F205:108B:718F:EEAD:CC70 (talk) 06:53, 27 April 2021 (UTC)[reply]

Irrellevant uncited junk and other damage to these articles

This article has become a total train wreck of irrelevant information. It is now composed of a ton of edits by editors where english is not their first language, and whose IP addresses originate in Russia, and have added unsupported opinion, and mangled or made so much of this into irrelevant babble it is shocking. What is going on? This is happening with a number of other related color articles. Myndex (talk) 01:43, 5 November 2021 (UTC)[reply]

"Editors" It was only me, in particluar alpha and beta info, etc. Please be more particular about what you do not like. I wanted to add more cites about 2.35 gamma. I do have them... I fully rewrote BT.2020, Pantone, BT.2100, modified BT.601, wrote a lot of xvYCC article, corrected key parts of Photo CD article, modified HDR articles, etc. 2A00:1FA0:4664:8ED4:CC39:8CA2:453B:D575 (talk) 21:05, 7 November 2021 (UTC)[reply]

What I "don't like" is random junk, and poorly written, passive voice, confusing, tangential, or irrelevant information that does not help the article nor pertain directly to BT.709. Myndex (talk) 13:58, 27 November 2021 (UTC)[reply]

You did not clarify what you don't like, are you saying that bt709 history is not complicated and its derivation is not important? Valery Zapolodov (talk) 12:40, 24 December 2021 (UTC)[reply]

Needs a better title

The title of this article is extremely nerdish jargon. It should be changed to "ITU-R BT.709 color space" or something of the sort.
Wikipedia is not a resource for specialists only. A Wikipedia article should be written and titled so as to be helpful to any reader who has a legitimate need to know about its topic. While editors must assume that the reader has enough background knowledge of math, physics, computers etc. to make sense out of the article, that assumed level should generally be well below that of an expert in the field. Jorge Stolfi (talk) 21:23, 19 December 2024 (UTC)[reply]

The article desribes the specification specifically (sorry) though. In fact some even started removing a lot of references here on key information from other Rec. and reports of ITU. Kinda bad. I do not like it. Valery Zapolodov (talk) 14:25, 11 February 2025 (UTC)[reply]

Key issues

No mention of 1.2 end-to-end system gamma concept, removed mention of dim surround effect. No mention of camera function OECF/OOTF, no mention of ITU Rec. 2035, no mention of BT.2390, mention of scene light removed in just 1 of 2 places, a lot of cites removed that were talking about it. Finally, no mention of 100 nits standard in the industry, 48 nits in cinema, and 108 nits in Dolby Cinema. Explain that 2.0 gamma in under the sun, 2.2 in artificial light office, 2.4 in dim room and 2.6 is for dark room like cinema. Maybe use Deepseek R1 to check all of these out and find sources and help to write an article. Older revision was quite chaotic, I agree, I did fix outright silly mistakes today: https://en.wikipedia.org/w/index.php?title=Rec._709&diff=prev&oldid=1174694776 Valery Zapolodov (talk) 14:47, 11 February 2025 (UTC)[reply]

Non-linear decoding is misleading in the age of LCD's

"In order to display the colors on a device, such as a HDTV monitor, the encoded values should be converted back to physical intensities of the primaries. Mathematically, the inverse of the non-linear encoding above would be: (goes on to show the inverse OETF)" I think this section is very misleading, but I'm not confident enough to correct the article as I only started to learn about this topic about a month ago. As I understand it LCD HDTV's do not apply a reverse rec. 709 OETF. As I understand it the OETF was chosen to produce a subjectively better looking picture in conjunction with display technology of the time. Flat panel TV's were then produced to match the EOTF characteristics of CRT's so the picture would look the same. If flat panel TV's instead applied the inverse OETF first they'd be undoing the camera's color adjustment and the picture would look different compared to a CRT. Maybe during the time when TV broadcasts were just camera signals spliced together applying an inverse OETF would be an acceptable way to get linear light intensities, which I doubt because the OETF was probably not implemented that precisely. But in modern times especially, camera's are digital and content is produced on a BT. 1886 display. That means the OETF is no longer relevant for anything. The only purpose I can think of is if you want linear light intensities out of a perfect analogue bt. 709 compliant camera for color grading. Unless an expert can explain that I am misunderstanding something I think the section should be rewritten to make it clear that the "Non-linear decoding" using the inverse OETF is not sensible or perhaps the section should be removed entirely and the article should explain the implicit color adjustment that happens in a traditional analog rec. 709 system from camera to display. Goeiecool9999 (talk) 16:12, 20 February 2025 (UTC)[reply]

Rec.709 displays use a OETF formula that generally matches CRT displays. This is mentioned in the article: "A suggested corresponding reference electro-optical transfer characteristic function for flat panel displays used in HDTV studio production has been specified in ITU-R BT.1886 and EBU Tech 3320." If you check BT1886 ( https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.1886-0-201103-I!!PDF-E.pdf ) you find the EOTF formula on the last page, and this text: "With the introduction of new display technologies which have entirely different characteristics to the CRT displays, it is necessary to define the EOTF of new devices that emulate that of the CRT displays." So the article is correct. 4throck (talk) 17:42, 20 February 2025 (UTC)[reply]

OETF cannot match a display, that is a EOTF... What are you even talking about? Valery Zapolodov (talk) 16:39, 25 February 2025 (UTC)[reply]