1、 Approved July 6, 2016 Copyright 2016 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 SMPTE ST 2094-20:2016 SMPTE STANDARD Dynamic Metadata for Color Volume Transform Application #2 Page 1 of 23 pages Table of Contents Page Foreword 2
2、Intellectual Property . 2 Introduction 2 1 Scope 3 2 Conformance Notation 3 3 Normative References 3 4 Terms and Definitions . 4 4.1 input image essence . 4 4.2 uv chromaticity coordinates 4 4.3 Yuv color space. 4 5 Application Identification . 4 6 Extension of the Processing Window . 4 6.1 Selectio
3、n of Pixels for Processing 4 6.2 Luminance Range Specification . 5 6.3 Chromaticity Area Specification 5 7 Color Volume Transform. 6 7.1 Saturation Gain Function 6 7.2 Tone Mapping Input Signal Weights. 6 7.3 Local Slope Adjustments 7 8 Application Constraints . 8 8.1 Metadata Set 8 8.2 Processing W
4、indow Constraints . 9 Annex A Mapping of Application #2 to the Generalized Color Volume Transform Model (Informative) . 10 Annex B Dynamic Range Transform Method Description (Informative) . 11 B.1 Introduction . 11 B.2 Extension of the Processing Window . 11 B.3 Gamut Shaping 13 B.4 Tone Mapping Pro
5、cess 14 Annex C Bibliography (Informative) 23 SMPTE ST 2094-20:2016 Page 2 of 23 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
6、 members in 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 coopera
7、tes closely 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 2094-20 was prepared by Technology Committee 10E. Intellectual Property SMPTE draws attention
8、 to the fact that it is claimed that compliance with this Standard may involve the use of one or more patents or other intellectual property rights (collectively, “IPR“). The Society takes no position concerning the evidence, validity, or scope of this IPR. Each holder of claimed IPR has assured the
9、 Society that it is willing to License all IPR it owns, and any third party IPR it has the right to sublicense, that is essential to the implementation of this Standard to those (Members and non-Members alike) desiring to implement this Standard under reasonable terms and conditions, demonstrably fr
10、ee of discrimination. Each holder of claimed IPR has filed a statement to such effect with SMPTE. Information may be obtained from the Director, Standards a fine-tuning adjustment to the region-based tone mapping curve; and parameters that specify luminance-dependent color saturation correction. In
11、some cases, it could be desirable to limit the number of parameters used. This could be the case, for example, in a live broadcast scenario. Typically, only one or two of the parameters that define the region-based tone mapping curve will be used. These parameters could be set by an operator, or cou
12、ld be automatically generated on the basis of a scene analysis. SMPTE ST 2094-20:2016 Page 3 of 23 pages 1 Scope This standard specifies the content-dependent Color Volume Transform metadata set for Application #2, a specialized model of the color volume transform defined by the core components docu
13、ment SMPTE ST 2094-1. The Color Volume Transform is based on a tone mapping curve that operates on image data in a perceptually-uniform domain and a luminance-dependent saturation gain curve. Both the tone mapping curve and the saturation gain curve are fully characterized by a set of parameters. 2
14、Conformance 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, o
15、r added editorially 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 keyw
16、ords “shall“ 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
17、 or excluding 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
18、 the document. 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 implementatio
19、n according 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 specifie
20、d, the order 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; then formal languages; then figures; and then any other language forms. 3 Normative References The following standards c
21、ontain provisions which, through reference in this text, constitute provisions of this engineering document. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this engineering document are encouraged to investigat
22、e the possibility of applying the most recent edition of the standards indicated below. SMPTE ST 2086:2014, Mastering Display Color Volume Metadata Supporting High Luminance and Wide Color Gamut Images SMPTE ST 2094-1:2016, Dynamic Metadata for Color Volume Transform Core Components SMPTE ST 2094-20
23、:2016 Page 4 of 23 pages ISO 11664-1:2007(E) / CIE S 014-1/E:2006, Colorimetry Part 1: CIE Standard Colorimetric Observers ISO 11664-3:2012(E) / CIE S 014-3/E:2011, Colorimetry Part 3: CIE Tristimulus Values ISO 11664-5:2009(E), Colorimetry Part 5: CIE 1976 L*u*v* Colour Space and u, v Uniform Chrom
24、aticity Scale Diagram 4 Terms and Definitions For the purposes of this document, the terms and definitions given in SMPTE ST 2094-1 and the following apply. 4.1 input image essence image essence to which the color volume transform is applied and having three color components labeled R, G and B, wher
25、e the R component corresponds to the Mastering Display Color Volume Display Primary with the largest x chromaticity coordinate, the G component corresponds to the Mastering Display Color Volume Display Primary with the largest y chromaticity coordinate, and the B component corresponds to the remaini
26、ng Mastering Display Color Volume Display Primary 4.2 uv chromaticity coordinates chromaticity coordinates u and v in the CIE 1976 u, v uniform chromaticity scale diagram, as specified in ISO 11664-5 4.3 Yuv color space color space with coordinates Y, u, v, where Y is the Y component of the CIE 1931
27、 standard colorimetric system defined in ISO 11664-1, and u, v are CIE 1976 chromaticity coordinates as defined in ISO 11664-5. 5 Application Identification The ApplicationIdentifier value shall be 2 and the ApplicationVersion value shall be 0. These two values identify this document as the defining
28、 document for the metadata set specified in Section 8.1. 6 Extension of the Processing Window 6.1 Selection of Pixels for Processing The extended processing window shall be the intersection of the ProcessingWindow as defined in SMPTE ST 2094-1 and a pixel selector. The pixel selector shall be a colo
29、r volume in the Yuv color space defined by the luminance range of Section 6.2 and the chromaticity area of Section 6.3. Zero or more extended processing windows shall be defined. Each extended processing window shall be associated with a set of metadata as defined in Section 7. SMPTE ST 2094-20:2016
30、 Page 5 of 23 pages 6.2 Luminance Range Specification 6.2.1 Luminance Lower Bound The LuminanceLowerBound shall be in the range 0, 4095 and in multiples of 1. The luminance lower value cd/m2 is calculated according to: Luminance Lower Value = 10(/1000) 1 (1) 6.2.2 Luminance Upper Bound The Luminance
31、UpperBound shall be in the range 0, 4095 and in multiples of 1. The value shall be no less than the LuminanceLowerBound. The luminance upper value cd/m2 is calculated according to: Luminance Upper Value = 10(/1000) 1 (2) 6.2.3 Luminance Range Selector The LuminanceRangeSelector shall be true to spec
32、ify that the Luminance Range is the closed range from Luminance Lower Bound to Luminance Upper Bound (including the bounds). The Luminance Range Selector shall be false to specify that the Luminance Range is the union of the open ranges below Luminance Lower Bound and above Luminance Upper Bound (ex
33、cluding the bounds). 6.3 Chromaticity Area Specification 6.3.1 Chromaticity Disk Center The Chromaticity Disk shall be a disk in the uv chromaticity plane. The ChromaticityDiskCenter shall specify the center of the Chromaticity Disk. The value shall be a uv chromaticity coordinate. The u and v value
34、 shall be in the range 0, 1023/1632 and in multiples of 1/1632. 6.3.2 Chromaticity Disk Radius The ChromaticityDiskRadius shall be the radius of the Chromaticity Disk. The value shall be in the range 0, 1023/1632 and in multiples of 1/1632. 6.3.3 Chromaticity Area Selector The ChromaticityAreaSelect
35、or shall be true to specify that the Chromaticity Area is the closed extent of the Chromaticity Disk. The Chromaticity Area Selector shall be false to specify that the Chromaticity Area is the open area outside the Chromaticity Disk. SMPTE ST 2094-20:2016 Page 6 of 23 pages 7 Color Volume Transform
36、7.1 Saturation Gain Function The SaturationGainFunction shall be a sampled function as defined in SMPTE ST 2094-1. It maps a luminance based input value to a saturation scaling factor. The first pair ( 0, 0 , where 0 = 0) may be omitted, in which case the first pair shall have the default value 0.0,
37、 0.0 . The last pair ( z, z , where z = 1 and +1 being the length of the list) may be omitted, in which case this last pair shall have the default value 1.0, 1.0 . This sampled function shall have no more than 6 pairs, excluding omitted pairs. The and values of the sampled function shall be multiple
38、s of 1/255. Before interpolation, the list of pairs shall be converted to a list of pairs, where: , = 215 , (3) The list of pairs shall be appended with a pair 0.0, 0.0 . The = () values shall be obtained through interpolation. The interpolation shall be linear interpolation. The processing of = ()
39、is: = + ( 1 ) ( 1 ) (4) where: = output value = input value = element in the list = element in the list = index into the list, such that . SMPTE ST 2094-20:2016 Page 19 of 23 pages () = , 0 2 + + , + 1 , 1 (18) = 0, = 00.5 , (19) = 0, = 01 + + 2 , (20) = 0, = 0( ) 2(1 )28 ( ) , (21) =1 2 (22) =1 +2
40、(23) =4 + 0.5 (24) = (,) where: = Maximum Display Mastering Luminance = TargetedSystemDisplayMaximumLuminance (25) = (26) =4 (27) =2 (28) = () (29) SMPTE ST 2094-20:2016 Page 20 of 23 pages Is adapted by the fine-tuning curve to arrive at . = (), 0 1, (30) The is linearly interpolated between given
41、, pairs as defined in ToneMappingOutputFineTuningFunction in Section 7.3.7. It is a sampled function that uses the generic Interpolation Between Samples method as described in SMPTE ST 2094-1. An example of the is depicted in Figure B.8. Figure B.8 Example ToneMappingOutputFineTuningFunction curve T
42、hen is calculated as per equation (32), using the Maximum Luminance of the targeted system . Equation (31) is the mathematical inverse function for equation (14). A graphical example of equation (32) is depicted in Figure B.9. (,) = () 1() 1 )2.4(31) = (,) where: = TargetedSystemDisplayMaximumLumina
43、nce (32) SMPTE ST 2094-20:2016 Page 21 of 23 pages Figure B.9 Example curve from perceptual to linear based on 100 cd/m2 The value of is calculated from a division of by the input : = , = 0 max( ,1), (33) Applying the Tone Mapping process As the final step of the HDR to SDR processing, the pixel com
44、ponents RHDR_S, GHDR_S, BHDR_S are multiplied by to produce the pixel components RSDR, GSDR, BSDR. () = (_) (34) SMPTE ST 2094-20:2016 Page 22 of 23 pages Overview The result of cascading all the operations in Annex B.4, is a curve as depicted on the bottom side of Figure B.10, taking linear light signals as input and producing linear light signals as output. The top side of Figure B.10 depicts again the control
