SMPTE ST 428-1-2006 D-Cinema Distribution Master Image Characteristics.pdf

1、 Table of contents Foreword Introduction 1 Scope 2 Normative references 3 Image structures 4 Colorimetry Annex A Digital cinema image aspect ratios Annex B Dynamic range usage of the DCDM Annex C Bibliography Foreword SMPTE (the Society of Motion Picture and Television Engineers) is an international

2、ly-recognized standards developing organization. Headquartered and incorporated in the United States 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 Techn

3、ology Committees. Participation in these Committees is open to all with a bona fide interest in their 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 i

4、ts Administrative Practices. SMPTE Standard 428-1 was prepared by SMPTE Technology Committee DC28. Page 1 of 8 pages SMPTE 428-1-2006 SMPTE STANDARD D-Cinema Distribution Master Image Characteristics Copyright 2006 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plai

5、ns, NY 10601 (914) 761-1100 Approved September 29, 2006 SMPTE 428-1-2006 Page 2 of 8 pages Introduction This standard describes the image characteristics of the Digital Cinema Distribution Master (DCDM). The image characteristics and parameters are not subject to any further image processing prior t

6、o the compression process described elsewhere. In order for content creators to convert a Digital Source Master (DSM) into a Digital Cinema Distribution Master (DCDM), this standard will define all of the metrics required for the image structure of the DCDM. This DCDM image structure may then be tra

7、nsported by being mapped into either real time interfaces or into file formats. In the process of creating theatrical releases, a Digital Source Master, or DSM, is produced from which many distribution elements are created, (e.g., Film Distribution Masters, Digital Cinema Distribution Masters (DCDM)

8、, Home Video Masters, Airline Version Masters and Broadcast Masters). It is not the goal of this specification to define the DSM. It is recognized that the DSM may consist of any color space, pixel matrix (spatial), frame rate (temporal), bit depth and many other metrics. This standard defines sets

9、of operational levels, in terms of the maximum number of pixels, H pixel count and V pixel count. In combination with the frame rate this determines the operational level, 1-3 as defined in Table 1. SMPTE 428-1-2006 Page 3 of 8 pages 1 Scope This standard defines the uncompressed image characteristi

10、cs for DCDM by specifying a pixel array, frame rate, pixel bit depth, and colorimetry. The DCDM image operational levels are defined by the maximum number of pixels and frame rate. 2 Normative references The following standards contain provisions which, through reference in this text, constitute pro

11、visions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. CIE Pub

12、lication15:2004, Colorimetry SMPTE 431-1-2006, D-Cinema Quality Screen Luminance Level, Chromaticity and Uniformity 3 Image structures The pixel array shall use equally sampled tristimulus code values to represent each pixel.1The maximum number of horizontal and vertical pixels shall be no greater t

13、han the limits of one of the operational levels as defined in Table 12. The number of pixels shall extend to the maximum in either one or both of the horizontal and vertical directions of the defined operational level. Table 1 DCDM operational levels Operational Level Maximum Horizontal Pixels Maxim

14、um Vertical Pixels Frames per Second 1 4096 2160 24 2 2048 1080 48 3 2048 1080 24 The pixel shall have an aspect ratio of 1:1. No anamorphic or other geometric distortions of the image data shall be permitted For operational level 1, the number of horizontal and vertical pixels shall be evenly divis

15、ible by four. For operational levels 2 and 3, the number of horizontal and vertical pixels shall be evenly divisible by two. 3.1 Pixel orientation and numbering The pixel orientation shall flow from left to right and top to bottom of the pixel array. The horizontal and vertical pixel count shall beg

16、in with 0. This is to mean that the top left pixel of the pixel array shall be notated as (0, 0). 1The pixel array is the set of pixels that are intended to be displayed on the cinema screen. 2Common film aspect ratios, unlike the native aspect ratio of the image boundaries shown in Table 1, shall b

17、e accommodated. Some examples of these are provided in the informative Annex A. SMPTE 428-1-2006 Page 4 of 8 pages 4 Colorimetry The color encoding of the Digital Cinema Distribution Master (DCDM) embodies a device-independent, XYZ color space as described in CIE Publication 15:2004, Colorimetry, 3r

18、d Edition. Because the DCDM incorporates all of the creative color decisions made in the mastering process, and these decisions are made on a calibrated projector in a controlled mastering room, it is by definition an output-referenced image state. The picture colorimetry is defined for its intended

19、 display on the cinema screen. 4.1 DCDM encoding primaries The DCDM shall use the CIE Publication15:2004, (x,y coordinates) to describe the color primaries X, Y, and Z as a gamut container. 4.2 Pixel bit depth The pixel bit depth for each code value for a color component shall be 12 bits. 4.3 Transf

20、er function The CIE XYZ3tristimulus values shall each be normalized with a constant that sets the Y tristimulus value equal to 1.0 for the reference luminance (L) where both X and Z values are multiplied by the same constant.4With this specification of the color, the following equations define the e

21、ncoding transfer function5, where X, Y, Z are the tristimulus values above black6. =6.2137.52*4095XLINTCVX=6.2137.52*4095YLINTCVY=6.2137.52*4095ZLINTCVZ3XYZ are the linear tristimulus values and are linear with light. XYZ are the symbols used in place of CVX, CVY, and CVZ. 4The peak luminance as sho

22、wn in the transfer function equation is 52.37 cd/m2. The extra headroom is reserved to accommodate a range of white points including D55, D61and D65, while still supporting the reference luminance (L) of 48 cd/m2 as specified in SMPTE 431-1,Table 5.2 for Digital Cinema-Screen Luminance Level, Chroma

23、ticity and Uniformity. 5The INT operator returns the value of 0 for fractional parts in the range of 0 to 0.4999 and +1 for fractional parts in the range 0.5 to 0.9999, i.e. it rounds up fractions above 0.5. 6This equation specifies luminance relative to the screen black level of the mastering envir

24、onment (the projectors response to a zero code value 0,0,0 input signal plus the operating ambient light of the room). Because tristimulus values are additive, the absolute luminance of the image seen can be found by adding the XYZ of the content to the XYZ of the black. SMPTE 428-1-2006 Page 5 of 8

25、 pages CVX: Code Value of X CVY: Code Value of Y CVZ: Code Value of Z L: Reference Luminance INT: Integer operator SMPTE 428-1-2006 Page 6 of 8 pages Annex A (informative) Digital cinema image aspect ratios Some examples of the accommodation of images of various aspect ratios are shown in Table A.1.

26、 Where: AR = the aspect ratio of the image (ratio of width to height, expressed as a decimal.) Ph = total number of horizontal pixels in image Pv = total number of vertical pixels in image Table A.1 Example image aspect ratios Level Ph Pv AR1 4096 1716 2.39:11 3996 2160 1.85:12&3 2048 858 2.39:12&3

27、1998 1080 1.85:1NOTE The Ph and Pv values must comply with the rules established in 3. SMPTE 428-1-2006 Page 7 of 8 pages Annex B (informative) Dynamic range usage of the DCDM The DCDM image characteristic specifies 12 bits resolution for each pixel and permits the range of values from 0 to 4095 (de

28、cimal). The 12-bit resolution is specified after a gamma transfer characteristic has been applied, thus the 12 bit digital samples represent the optical amplitude in a non-linear manner. This has a particular impact around low amplitude levels. B.1 Black and white levels SMPTE RP 431-2 defines the c

29、alibration white point of the Reference projector as having x y Y values of 0.314, 0.351, 48.00. The XYZ tristimulus values that are associated with these x y Y values are: X=42.94, Y=48.00, Z=45.82 Although the DCDM encoding is defined for XYZ above black, the white is so far above black that the b

30、lack can be ignored for the white calculations. From the DCDM encoding equations, the code values for this white point are: CVx= 3794, CVy= 3960, CVz= 3890. None of these values exceed the maximum value of 4095 and the headroom for the value 3960 is 135 code values. The minimum DCDM code value allow

31、ed is 0. Because the DCDM encoding is defined for XYZ above black, the set of DCDM code values CVX = 0, CVY=0, and CVZ = 0 defines a luminance above black of 0, which means theater black. Assume a projector and theater have a 2000:1 or a 4000:1 contrast ratio. For a 2000:1 contrast ratio the delta X

32、YZ values above black that are one JND (Just Noticable Difference) above black are approximately: delta X = 0.00043, delta Y = 0.00048, delta Z = 0.00046 and CVX= 45, CVY= 47, CVZ= 46 The headroom is 45 code values. For a 4000:1 contrast ratio the delta XYZ values above black that are one JND (Just

33、Noticeable Difference) above black are approximately: delta X = 0.00021, delta Y = 0.00024, delta Z = 0.00023 and CVX = 35, CVY= 36, CVZ = 36 The headroom is 35 code values. B.2 Impact on signal processing All equipment should be able to handle any signal over the full range of 0 to 4095. However, c

34、ertain signal processing operations may cause a signal that has been processed to overshoot these 12-bit integer minimum and maximum values. For example, a filtering operation may result in transient overshoots and undershoots. SMPTE 428-1-2006 Page 8 of 8 pages Annex C (informative) Bibliography SMPTE RP 431-2, D-Cinema Quality Reference Projector and Environment for the Display of DCDM in Review Rooms and Theaters SMPTE EG 432-1, Digital Source Processing Color Processing for D-Cinema