SMPTE ST 2084-2014 High Dynamic Range Electro - Optical Transfer Function of Mastering Reference Displays.pdf

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1、 Copyright 2014 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved August 16, 2014 Table of Contents Page Foreword . 3 Intellectual Property 3 Introduction 3 1 Scope . 4 2 Conformance Notation . 4 3 Terms . 4 3.1 Color Value 4 3.

2、2 Digital Code Value . 4 3.3 Electro-Optical Transfer Function (EOTF) . 4 3.4 High Dynamic Range . 5 3.5 Linear Color Value . 5 3.6 Nonlinear Color Value 5 4 Reference EOTF 5 4.1 Linearization and Scaling . 5 4.2 EOTF Linearization Equation . 5 4.3 EOTF Level Calibration Equation 6 4.4 Mastering Ref

3、erence Viewing Environments . 6 5 Reference Inverse-EOTF . 6 5.1 Linearization and Scaling . 6 5.2 Inverse-EOTF Normalization Equation 6 5.3 Inverse-EOTF Nonlinear Encoding Equation . 7 Annex A Example Digital Representations (Informative) 8 A.1 Digital Representations 8 A.2 Full Range Code Value Ma

4、pping . 8 A.3 Inverse Full Range Code Value Mapping 8 A.4 Reserved Code Values 8 A.5 SDI Range Code Value Mapping . 9 A.6 Inverse SDI Range Code Value Mapping 9 A.7 Narrow Range Code Value Mapping . 10 A.8 Inverse Narrow Range Code Value Mapping 10 A.9 Clamping Function for Inverse Code Value Mappin

5、g . 10 A.10 Inverse SDI Range Code Value Mapping with Clamping . 10 A.11 Inverse Narrow Range Code Value Mapping with Clamping 11 Page 1 of 14 pages SMPTE ST 2084:2014 SMPTE STANDARD High Dynamic Range Electro-Optical Transfer Function of Mastering Reference Displays SMPTE ST 2084:2014 Page 2 of 14

6、pages Annex B Example Reference Viewing Environments (Informative) . 12 B.1 Consistency with Traditional Program Production Environments 12 B.2 Reference Viewing Environment for HDTV 12 B.3 Reference Viewing Environment for Digital Cinema 12 Annex C Example Inverse-EOTF Use Case (Informative) . 13 A

7、nnex D Bibliography (Informative) 14 SMPTE ST 2084:2014 Page 3 of 14 pages Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an internationally-recognized standards developing organization. Headquartered and incorporated in the United States of America, SMPTE has members in

8、over 80 countries on six continents. SMPTEs Engineering Documents, including Standards, Recommended Practices, and Engineering Guidelines, are prepared by SMPTEs Technology Committees. Participation in these Committees is open to all with a bona fide interest in their work. SMPTE cooperates closely

9、with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in its Standards Operations Manual. SMPTE ST 2084 was prepared by Technology Committee 10E. Intellectual Property At the time of publication no notice

10、 had been received by SMPTE claiming patent rights essential to the implementation of this Engineering Document. However, attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. SMPTE shall not be held responsible for identifying any or a

11、ll such patent rights. Introduction This section is entirely informative and does not form an integral part of this Engineering Document. This standard defines an electro-optical transfer function (EOTF) with a high luminance range capability of 0 to 10,000 cd/m2. Because this EOTF is referenced to

12、absolute luminance, the display is assumed to be operating in a specified reference viewing environment, two examples of which are given in Annex B of this document. The EOTF does not impart a preferred rendering appearance for any particular viewing environment. Image modifications needed for viewe

13、r contrast, colorfulness, highlight details, and visible detail in shadows at any particular output level must be chosen as part of the mastering process. This EOTF is intended to enable the creation of video images with an increased luminance range; not for creation of video images with overall hig

14、her luminance levels. For consistency of presentation across devices with different output brightness, average picture levels in content would likely remain similar to current luminance levels; i.e. mid-range scene exposures would produce currently expected luminance levels appropriate to video or c

15、inema. With this EOTF, the upper range of scene exposures would not need to be highly compressed as in traditional video and images with increased realism and sense of presence can be presented. The reference EOTF is specified by an equation with four independent parameters. With a foundation based

16、on human visual perception, this EOTF creates an efficient mapping from digital code values containing as few as 10 bits to a large, absolute luminance range of 0 to 10,000 cd/m2. System implementations that utilize this EOTF will be able to represent a luminance level of 10,000 cd/m2 at their nativ

17、e white point, but can not represent that luminance level at all other chromaticity points. An example of this would be an XYZ system implementation, which could represent 10,000 cd/m2 at the equal energy white point E, but could only represent about 9187 cd/m2 at D65. The reference EOTF and its inv

18、erse represent an efficient encoding system for high luminance range data. Though an idealized display device could follow this EOTF exactly, in real world displays the EOTF can be thought of as a nominal target. Actual displays can vary from the absolute curve due to output limitations and effects

19、of non-ideal viewing environments. SMPTE ST 2084:2014 Page 4 of 14 pages 1 Scope This standard specifies an EOTF characterizing high-dynamic-range reference displays used primarily for mastering non-broadcast content. This standard also specifies an Inverse-EOTF derived from the EOTF. 2 Conformance

20、Notation Normative text is text that describes elements of the design that are indispensable or contains the conformance language keywords: “shall“, “should“, or “may“. Informative text is text that is potentially helpful to the user, but not indispensable, and can be removed, changed, or added edit

21、orially without affecting interoperability. Informative text does not contain any conformance keywords. All text in this document is, by default, normative, except: the Introduction, any section explicitly labeled as “Informative“ or individual paragraphs that start with “Note:” The keywords “shall“

22、 and “shall not“ indicate requirements strictly to be followed in order to conform to the document and from which no deviation is permitted. The keywords, “should“ and “should not“ indicate that, among several possibilities, one is recommended as particularly suitable, without mentioning or excludin

23、g others; or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited. The keywords “may“ and “need not“ indicate courses of action permissible within the limits of the documen

24、t. The keyword “reserved” indicates a provision that is not defined at this time, shall not be used, and may be defined in the future. The keyword “forbidden” indicates “reserved” and in addition indicates that the provision will never be defined in the future. A conformant implementation according

25、to this document is one that includes all mandatory provisions (“shall“) and, if implemented, all recommended provisions (“should“) as described. A conformant implementation need not implement optional provisions (“may“) and need not implement them as described. Unless otherwise specified, the order

26、 of precedence of the types of normative information in this document shall be as follows: normative prose shall be the authoritative definition; tables shall be next; followed by formal languages; then figures; and then any other language forms. 3 Terms The following terms are described only as use

27、d in this context of this document: 3.1 Color Value A number corresponding to the amount of a specific color component (such as R, G, B, or Y) for an image element. 3.2 Digital Code Value Digital representation of an image signal value. Usually representative of a nonlinear color value. 3.3 Electro-

28、Optical Transfer Function (EOTF) Relationship between the nonlinear color values provided to a display device and the linear color values produced by the device. SMPTE ST 2084:2014 Page 5 of 14 pages 3.4 High Dynamic Range A term used to describe an image or imaging device that spans or is capable o

29、f spanning a range of luminance levels greater than the range of luminance levels spanned by traditional imaging systems. This standard assumes a peak luminance level limited to 10,000 cd/m2. 3.5 Linear Color Value Color Value abbreviated as L, normalized to the range 0,1, that is directly proportio

30、nal to the optical output of a display device, and which is not directly proportional to the encoded signal representation. 3.6 Nonlinear Color Value Color Value abbreviated as N, normalized to the range 0,1, that is directly proportional to the encoded signal representation, and which is not direct

31、ly proportional to the optical output of a display device. 4 Reference EOTF 4.1 Linearization and Scaling The EOTF transforms a nonlinear color value N into an optical output value C. The EOTF transform shall be split into two steps: a linearization equation followed by a level calibration equation

32、as defined in Sections 4.2 and 4.3. 4.2 EOTF Linearization Equation The linear color values proportional to the desired optical output denoted by L are related to the nonlinear color values proportional to an input signal denoted by N. This relationship shall be defined by the EOTF linearization equ

33、ation: Equation 4.1 ( ) )where N denotes a nonlinear color value L denotes the corresponding linear color value m1 is the number m2 is the number c1 is the number c2 is the number c3 is the number SMPTE ST 2084:2014 Page 6 of 14 pages 4.3 EOTF Level Calibration Equation The EOTF linearization equati

34、on 4.1 was constructed to align with human visual contrast sensitivities over a specific range of luminance values, therefore the absolute optical output shall be defined as: Equation 4.2 where L denotes the linear color value C denotes the corresponding optical output value C represents luminance i

35、n candelas per square meter (cd/m2) when all three component values of a linear additive tristimulus system are equal to L or a system contains a linear luminance component value Y that is equal to L, and any other color components are set to their native white point These relationships simply state

36、: When a system is set to make an output at the systems native white point at some normalized level L lying in the range 0 to 1, the target optical output C in cd/m2 of the ideal reference display is 0 cd/m2 to 10,000 cd/m2. 4.4 Mastering Reference Viewing Environments A reference display using the

37、EOTF equations 4.1 and 4.2 and operating in a defined mastering reference viewing environment can contribute to visual consistency. Some examples of mastering reference viewing environments are presented in Annex B. 5 Reference Inverse-EOTF 5.1 Linearization and Scaling An Inverse-EOTF transform con

38、verts an optical output value C to a nonlinear color value N. The inverse EOTF transform shall be split into two steps: a normalization equation followed by a nonlinear encoding equation as defined in Sections 5.2 and 5.3. 5.2 Inverse-EOTF Normalization Equation The Inverse-EOTF normalization equati

39、on shall be defined as follows: Equation 5.1 where C denotes an optical output value L denotes the corresponding linear color value SMPTE ST 2084:2014 Page 7 of 14 pages C represents the luminance in candelas per square meter (cd/m2) when all three component values of a linear additive tristimulus s

40、ystem are equal to L or a system contains a linear luminance component value Y that is equal to L, and any other color components are set to their native white point 5.3 Inverse-EOTF Nonlinear Encoding Equation The Inverse-EOTF nonlinear encoding equation shall be defined as follows: Equation 5.2 (

41、)where L denotes a linear color value N denotes the corresponding nonlinear color value m1 is the number m2 is the number c1 is the number c2 is the number c3 is the number SMPTE ST 2084:2014 Page 8 of 14 pages Annex A Example Digital Representations (Informative) A.1 Digital Representations Three e

42、xample digital representations are shown which encode nonlinear component values into digital code values. The first representation utilizes all available code values, while the second and third representations are constructed such that reserved code values for traditional video signaling purposes a

43、re not used, while maintaining range consistency among multiple bit depths between 10 and 16 bits per component. A.2 Full Range Code Value Mapping Full range digital code values are computed as follows: Equation A.1 ( ) ) where N is the nonlinear color value from zero to unity CVF is the resulting f

44、ull range digital code value b takes a value between 10 to 16 inclusive, corresponding to the number of bits per code word The unary function Floor yields the largest integer not greater than its argument. This scaling places the extrema of N at code words 0h(0) and 3FFh(1023) in a 10-bit representa

45、tion, code words 0h(0) and FFFh(4095) in a 12-bit representation, code words 0h(0) and 3FFFh(16,383) in a 14-bit representation, or code words 0h(0) and FFFFh(65,535) in a 16-bit representation. A.3 Inverse Full Range Code Value Mapping Normalized nonlinear color values N are computed from their ful

46、l range digital code values as follows: Equation A.2 ( ) where CVF is the components full range digital code value N is the nonlinear color value from zero to unity b takes a value between 10 to 16 inclusive, corresponding to the number of bits per code word A.4 Reserved Code Values For some serial

47、digital interfaces currently in use, such as SMPTE ST 292-1, code values having the 8 most-significant bits all zero or all one for example, 10-bit codes 000h(0) through 003h(3) and 3FCh(1020) through 3FFh(1023) in the case of a 10-bit system, or 12-bit codes 000h(0) through 00Fh(15) and FF0h(4080)

48、through FFFh(4095) in the case of a 12-bit system are employed for synchronizing purposes and are SMPTE ST 2084:2014 Page 9 of 14 pages excluded from video or ancillary data/signals. By extension, equivalent ranges for 14-bit and 16-bit systems would also be excluded from use for picture information

49、. The excluded values are: System Bit Depth Low Excluded Values High Excluded Values 10-bit systems 000h(0) through 003h(3) 3FCh(1020) through 3FFh(1023) 12-bit systems 000h(0) through 00Fh(15) FF0h(4080) through FFFh(4095) 14-bit systems 0000h(0) through 003Fh(63) 3FC0h(16,320) through 3FFFh(16,383) 16-bit systems 0000h(0) through 00FFh(255) FF00h(65,280) through FFFFh(65,53