1、 Copyright 2011 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved April 6, 2011 Table of Contents Page Foreword . 2Intellectual Property 2 Introduction 2 1 Scope . 3 2 Conformance Notation . 3 3 Normative References . 3 4
2、Input Requirements 4 5 Initial Conditions . 4 6 Environment . 4 6.1 Ambient Level 4 6.2 Screen Characteristics . 4 6.3 Reference Viewing Position for Color Grading 4 7 Image Parameters 5 7.1 7.1 Pixel Count 5 7.2 Luminance Uniformity 5 7.3 Calibration White Point and Luminance . 5 7.4 Color Uniformi
3、ty of White Field 5 7.5 Sequential Contrast 5 7.6 Intra-frame (Checkerboard) Contrast . 5 7.7 Transfer Function . 6 7.8 Color Gamut . 6 7.9 Color Accuracy . 6 Annex A Normative Tables . 7 Annex B Subjective Parameters (Informative) . 10 B.1 Grayscale Tracking 10 B.2 Contouring 10 B.3 Temporal Artifa
4、cts 10 Annex C Xenon Color Primaries, White Point and Color Conversions (Informative) . 11 C.1 Color Primaries 11 C.2 White Reference 11 C.3 Brightness 11 C.4 Color Conversion to XYZ . 11 Annex D Bibliography (Informative) . 14 Page 1 of 10 pages SMPTE RP 431-2:2011 Revision of RP 431-2-2007 SMPTE R
5、ECOMMENDED PRACTICE D-Cinema Quality Reference Projector and Environment SMPTE RP 431-2:2011 Page 2 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 Sta
6、tes of America, SMPTE has 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 t
7、heir work. SMPTE cooperates closely with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Documents are drafted in accordance with the rules given in Part XIII of its Administrative Practices. SMPTE RP 431-2 was prepared by SMPTE Technology Committee 21DC on Di
8、gital Cinema. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rights essential to the implementation of this Standard. However, attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights.
9、SMPTE shall not be held responsible for identifying any or all such patent rights. Introduction The creation and exhibition of a Digital Cinema Distribution Master (DCDM) requires the definition of a Reference Projector and controlled environment, as well as carefully calibrated projectors for Revie
10、w Rooms and Theaters. This document defines the Reference Projector and specifies the tolerances around the critical image parameters for Review Rooms and Theaters so that consistent and repeatable color quality can be achieved. After initial publication of this Recommended Practice, there was confu
11、sion concerning the alignment of the luminance at a given white point. Practice in the field made the assumption either that the Mastering White was Calibration White (48 cd/m2at x=0.314, y=0.351) or that projectors aligned to Calibration White would support other DCDM Mastering Whites properly with
12、out clipping. In the former case there was content being mastered at different white points and in the latter case both alignment procedures and internal test signals were incorrectly applied causing some projectors to clip the highlight portion of the content. Recognizing this, SMPTE formed a White
13、 Gamut Practices Study Group which, upon concluding its work, recommended modifications to this Recommended Practice to include a White Gamut that incorporates the set of possible Mastering Whites that can be reproduced by the Reference Projector at a luminance of 48 cd/m2. Along with this a new ter
14、m was introduced, Virtual White, defined within Table A-1. Virtual White is only a mathematical result and is not intended for display or measurement because it might be clipped by a display system. Virtual White is used to define the relative balance of display primaries so that the White Gamut wil
15、l be displayed with a luminance of 48 cd/m2. For more detail and explanation on this topic please refer to the White Gamut Practices Study Group Report. SMPTE RP 431-2:2011 Page 3 of 14 pages 1 Scope This document defines the Reference Projector and its controlled environment, along with the accepta
16、ble tolerances around critical image parameters for Review Room and Theatre applications. The goal is to provide a means for achieving consistent and repeatable color image quality. The Reference Projector is a practical device. The nominal (Reference Projector) parameters are based on industry expe
17、rience and have been demonstrated by commercially available projectors in controlled environments. Two levels of tolerances are specified, a tighter tolerance for Review Rooms1where critical color judgments are made, and a wider tolerance for satisfactory reproduction in Theaters used for general pu
18、blic exhibition. 2 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
19、removed, changed, or 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 wi
20、th “Note:” The keywords “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,
21、 without mentioning 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 w
22、ithin the limits of 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. Unless
23、otherwise specified 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, followed by formal languages, then figures, and then any other language forms. 3 Normative References N
24、ote: All references in this document to other SMPTE documents use the current numbering style (e.g. SMPTE ST 428-1:2006) although, during a transitional phase, the document as published (printed or PDF) may bear an older designation (such as SMPTE 428-1-2006). Documents with the same root number (e.
25、g. 428-1) and publication year (e.g. 2006) are functionally identical. The following standards contain provisions which, through reference in this text, constitute provisions of this recommended practice. At the time of publication, the editions indicated were valid. All standards are subject to rev
26、ision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. SMPTE ST 428-1:2006, D-Cinema Distribution Master (DCDM) Image Characteristics 1The use of the term “Review Room” in
27、cludes the mastering environment where creative color decisions are made on a projected image. SMPTE RP 431-2:2011 Page 4 of 14 pages SMPTE ST 431-1:2006, D-Cinema Quality Screen Luminance Level, Chromaticity and Uniformity CIE Publication 15.2 (1986), Colorimetry CIE Publication 15:2004, Colorimetr
28、y, 3rdEdition 4 Input Requirements The Reference Projector shall support the DCDM image structures, and at a minimum, DCDM operational level 3, as defined in SMPTE ST 428-1. 5 Initial Conditions The projector shall be turned on (including the lamp house) and allowed to thermally stabilize for 20 to
29、30 minutes prior to all measurements. The room lights shall be turned off, with the exception of the minimal lighting provided for working or safety reasons. The projector shall be calibrated to the target image parameters in Table A.1 before final measurements are made. 6 Environment 6.1 Ambient Le
30、vel Stray light reflected from the screen should be minimized. Black, non-reflective finishes on all surfaces other than the screen, along with recessed lighting, should be used. With the projector turned off (or with the lamp house doused), measure the luminance of the center of the screen. For Rev
31、iew Rooms, the ambient light level reflected by the screen should be less than 0.01 cd/m2(0.0029 ft L ). For Exhibition Theaters, the ambient light level reflected by the screen should be less than 0.03 cd/m2(0.01 ft L). Safety regulations and the placement of exit lights or access lights may result
32、 in a higher ambient light level, but it should be noted that this will reduce the contrast of the projected image. 6.2 Screen Characteristics The screen shall reflect energy uniformly across all angles, such that the color of the reflected light does not change with viewing angle. If the design of
33、the room requires the placement of speakers behind the screen, it may be necessary to use perforations; however, care should be taken to ensure that the perforation structure does not beat against (alias with) the projectors display structure. The screen shall have adjustable black masking that can
34、be adjusted to tightly frame the projected image, for both 1.85:1 and 2.39:1 image formats. 6.3 Reference Viewing Position for Color Grading The reference viewing position for color grading shall be at a viewing distance of 1.5 to 3.5 screen heights (for constant height presentation), or if constant
35、 width is used for both 2.39:1 and 1.85:1 aspect ratios, then this viewing distance refers to the height of the 1.85:1 picture. Lighting on work surfaces or consoles should be masked and filtered to eliminate any spill onto the screen. SMPTE RP 431-2:2011 Page 5 of 14 pages 7 Image Parameters All im
36、age parameters shall be measured as reflected light from the screen, with the measurements made from the reference viewing position in the Review Room, or from the center of the normal seating area in an Exhibition Theatre. The nominal (Reference Projector) parameters and the tolerances for Review R
37、ooms and Exhibition Theaters are summarized in Table A.1. 7.1 7.1 Pixel Count The sampling structure of the displayed picture (pixel count) shall be a minimum of 2048 (2k) horizontal and 1080 vertical pixels. 7.2 Luminance Uniformity The lamp house shall be aligned such that the luminance fall-off f
38、rom center to corners is within the specified tolerances. The measured luminance of the corners and sides in a 3 by 3 grid shall be within the tolerances specified by SMPTE ST 431-1. 7.3 Calibration White Point and Luminance When the projector is sent a full frame Reference White image with the code
39、 values 3794 X 3960 Y 3890 Z2, the white point chromaticity coordinates of the center of the screen shall be specified by SMPTE ST 431-1. These code values shall produce a screen reflected luminance as specified by SMPTE ST 431-1 and SMPTE ST 428-1. 7.4 Color Uniformity of White Field The chromatici
40、ties of the center points of a equally spaced 3x3 grid shall be within the tolerances specified in SMPTE ST 431-1. 7.5 Sequential Contrast The sequential contrast ratio shall be computed by dividing the white luminance (of a peak white field as defined in Section 7.3) by the black luminance (of a co
41、de value zero black field), with the measurements made in-situ including the contributions of ambient light. It shall not be appropriate to subtract the room black (ambient light) when computing sequential contrast. The nominal value for the sequential contrast should be a least 2000:1 (in a darkene
42、d room). The tolerances for Review Rooms and Exhibition Theaters are shown in Table A.1. In order to eliminate unwanted detail or discoloration in near blacks, Review Rooms used for color grading should have an equal or higher sequential contrast than the best of Exhibition Theaters. 7.6 Intra-frame
43、 (Checkerboard) Contrast Using a 4x4 checkerboard target, intra-frame contrast shall be computed by summing the luminances of the white patches and dividing by the sum of the luminances of the black patches. The nominal (Reference Projector) value for intra-frame contrast shall be minimum contrast o
44、f 150:1. The tolerances for Review Rooms and Exhibition Theaters are shown in Table A.1. Note: Infra-frame contrast is reduced by many factors including projection lens flare, port glass flare, ambient light spilling on the screen and back-reflections from the room itself. This measurement is made w
45、ith the projector “in situ”, with the screening room or theatre in full operating mode. 2At the time of the writing of this Recommended Practice, the XYZ code values specified are for the white point chromaticity coordinates of (0.314 x, 0.351 y. If this white point chromaticity is changed, the best
46、 practice is to change XYZ code values accordingly. SMPTE RP 431-2:2011 Page 6 of 14 pages 7.7 Transfer Function The encoding transfer function shall be defined in terms of output-referred CIE XYZ tristimulus values, as described in SMPTE Standard for D-Cinema Distribution Master- Image Structure. T
47、he projector transfer functions are: 6.24095/=XLPX 6.24095/=YLPY 6.24095/=ZLPZ where P = 52.37, and L shall be the Reference White Luminance. The peak luminance as shown in the transfer function equation shall be 52.37 cd/m2. The extra headroom is reserved to accommodate a range of white points incl
48、uding D55, D61and D65, while still supporting the reference white luminance of 48 cd/m2 as specified in SMPTE ST 431-1. Note 1: In practice, Luminance at the bottom end of the transfer function is skewed by ambient light and finite projector sequential contrast. This transfer function does not attem
49、pt to correct for the resulting deviation from a pure power law., as tests have shown that corrections can produce undesirable clipping artefacts. Linearity and sensitivity of the photometer are critical for useful measurements. Note 2: If the data is transported over SMPTE ST 372 (SDI dual link), code values 0-15 and 4080-4095 are reserved (illegal) code values and these code values will be clipped. 7.8 Color Gamut In an additive display, the color gamut is a cuboid with vertices determined by the XY
