查看“︁基于感知的量化器”︁的源代码

'''基于感知的量化器'''（{{lang-en|Perceptual Quantizer}}）或'''感知量化'''（{{lang-en|Perceptual Quantization}}）是一种用于[[高動態範圍]]（HDR）图像的[[传递函数]]<ref name="DolbyVisionWhitePaper">{{Cite web|title=Dolby Vision Whitepaper|url=http://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf|last=Dolby Laboratories|url-status=live|archive-url=https://web.archive.org/web/20160604120415/http://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-white-paper.pdf|archive-date=2016-06-04|access-date=2016-08-24}}</ref>。它可用于亮度水平在0.0001[[尼特]]到10000尼特间的图像的复现。<ref name="DolbyVisionWhitePaper" />

PQ是一种基于人类视觉对[[色彩帶|条带]]的感知的非线性传递函数，它在编码HDR内容时较{{Tsl|en|ITU-R_BT.1886|4=BT.1886}}更为高效。仅使用12位[[色彩深度|色深]]，PQ便可以将条带控制在人类可感知的范围外。而同等峰值亮度下，BT.1886需要15位色深才能达到类似效果。<ref name="HPATechFebruary2014">{{Cite news|author=Adam Wilt|date=2014-02-20|title=HPA Tech Retreat 2014 – Day 4|publisher=DV Info Net|url=http://www.dvinfo.net/article/trip_reports/hpa-tech-retreat-2014-day-4.html|accessdate=2014-11-05|archiveurl=https://web.archive.org/web/20141101213814/http://www.dvinfo.net/article/trip_reports/hpa-tech-retreat-2014-day-4.html|archivedate=2014-11-01}}</ref>

PQ由[[杜比實驗室|杜比]]<ref name=":52">{{Cite web|title=Dolby Vision Whitepaper - An introduction to Dolby Vision|url=https://professional.dolby.com/siteassets/pdfs/dolby-vision-whitepaper_an-introduction-to-dolby-vision_0916.pdf|website=|date=|last=Dolby|access-date=2021-02-14}}</ref>开发，2014年由[[电影电视工程师协会|电影电视工程师协会（SMPTE）]]标准化为SMPTE ST 2084<ref name="SMPTE2084HDR2014">{{Cite news|title=ST 2084:2014|publisher=[[IEEE Xplore]]|url=https://ieeexplore.ieee.org/document/7291452|accessdate=2020-07-24|archiveurl=https://web.archive.org/web/20200724211453/https://ieeexplore.ieee.org/document/7291452|archivedate=2020-07-24|doi=10.5594/SMPTE.ST2084.2014|isbn=978-1-61482-829-7}}</ref>'''。'''2016年，[[国际电信联盟|ITU]]在{{Tsl|en|Rec.2100}}中推荐HDR TV使用{{Tsl|en|Hybrid_log–gamma|4=HLG}}和PQ两种传递函数。<ref name="Recommendation2100">{{Cite news|author=|first=|date=2016-07-04|title=BT.2100 : Image parameter values for high dynamic range television for use in production and international programme exchange|work=|publisher=International Telecommunication Union|url=https://www.itu.int/rec/R-REC-BT.2100|accessdate=2021-01-25|archiveurl=https://web.archive.org/web/20190427004028/https://www.itu.int/rec/R-REC-BT.2100|archivedate=2019-04-27}}</ref><ref name="ITUAnnouncesHDRJuly2016">{{Cite news|date=2016-07-05|title=ITU announces BT.2100 HDR TV standard|publisher=Rasmus Larsen|url=https://www.flatpanelshd.com/news.php?subaction=showfull&id=1467719709|accessdate=2016-07-26|archiveurl=https://web.archive.org/web/20160710015254/http://www.flatpanelshd.com/news.php?subaction=showfull&id=1467719709|archivedate=2016-07-10}}</ref>

PQ是多种HDR视频格式的基础（如[[杜比视界]]<ref name="DolbyVisionWhitePaper" /><ref name=":332">{{Cite web|title=Dolby Vision Profiles and Levels Version 1.3.2 - Specification|url=https://professional.dolby.com/siteassets/content-creation/dolby-vision-for-content-creators/dolbyvisionprofileslevels_v1_3_2_2019_09_16.pdf|website=|date=|last=Dolby|url-status=dead|archive-url=https://web.archive.org/web/20200929014520/https://professional.dolby.com/siteassets/content-creation/dolby-vision-for-content-creators/dolbyvisionprofileslevels_v1_3_2_2019_09_16.pdf|archive-date=2020-09-29|access-date=2021-02-12}}</ref>、[[HDR10]]<ref name=":02">{{Cite web|title=CEA Defines 'HDR Compatible' Displays|url=https://www.cta.tech/News/Press-Releases/2015/August/CEA-Defines-‘HDR-Compatible’-Displays.aspx|website=|date=2015-08-27|last=Consumer Technology Association|url-status=live|archive-url=https://web.archive.org/web/20190611151620/https://www.cta.tech/News/Press-Releases/2015/August/CEA-Defines-%E2%80%98HDR-Compatible%E2%80%99-Displays.aspx|archive-date=2019-06-11|access-date=2021-02-12}}</ref>和[[HDR10+]]<ref name=":22">{{Cite web|title=HDR10+ System Whitepaper|url=https://hdr10plus.org/wp-content/uploads/2019/08/HDR10_WhitePaper.pdf|website=|date=2019-09-04|last=HDR10+ Technologies, LLC|access-date=2021-02-12}}</ref>），也被用于HDR静态图像格式<ref name=":15">{{Cite web|title=AV1 Image File Format (AVIF)|url=https://aomediacodec.github.io/av1-avif/|website=aomediacodec.github.io|access-date=2021-01-31}}</ref><ref name=":16">{{Cite web|title=Canon EOS-1D X Mark III Review|url=https://www.the-digital-picture.com/Reviews/Canon-EOS-1D-X-Mark-III.aspx|website=The-Digital-Picture.com|access-date=2021-02-15}}</ref>。PQ与BT.1886 EOTF（即SDR使用的[[伽瑪校正|伽马曲线]]）不兼容，而HLG与后者相兼容。

== 技术细节 ==
PQ EOTF（{{Tsl|en|Transfer_functions_in_imaging|4=电光传递函数}}）如下：<ref name="Recommendation2100"/><ref>{{Cite web|title=BT.2124 : Objective metric for the assessment of the potential visibility of colour differences in television|url=https://www.itu.int/rec/R-REC-BT.2124/en|website=www.itu.int|access-date=2021-04-29}}</ref>

<math>F_D = EOTF[E'] = 10000 \left( \frac{\max[ (E'^{1/m_2} - c_1), 0]} {c_2 - c_3 \cdot E' ^ {1/m_2} } \right) ^ {1/ m_1}
</math>

PQ逆EOTF如下：

<math>E' = EOTF^{-1}[F_D] = \left( \frac{c_1 + c_2 \cdot Y^{m_1}}{1 + c_3 \cdot Y^{m_1} } \right)^{m_2}</math>

其中：

* <math>E'</math>代表非线性信号值，范围为<math>\left[0, 1 \right]</math>。
* <math>F_D</math>代表显示亮度，单位为cd/m<sup>2</sup>（[[坎德拉每平方米|坎德拉/平方米]]）
* <math>Y = F_D/10000</math>是[[标准化 (统计学)|标准化]]的线性显示值，范围为[0:1]（其中<math>Y = 1</math>代表峰值亮度10000cd/m<sup>2</sup>
* <math>m_1 = \frac{2610}{16384} = \frac{1305}{8192} = 0.1593017578125</math>
* <math>m_2 = 128 \frac{2523}{4096} = \frac{2523}{32} = 78.84375</math>

* <math>c_1 = \frac{3424}{4096} = \frac{107}{128} = 0.8359375 = c_3 - c_2 + 1 </math>
* <math>c_2 = 32 \frac{2413}{4096} = \frac{2413}{128} = 18.8515625</math>
* <math>c_3 = 32 \frac{2392}{4096} = \frac{2392}{128} = 18.6875</math>

== 扩展阅读 ==

* {{Tsl|en|Transfer functions in imaging|4=应用在图像中的传递函数}}
* {{Tsl|en|High-dynamic-range_television|4=HDR电视}}

== 参考 ==
{{Reflist}}

[[Category:传递函数]]