SMPTE ST 2065-3-2012 Academy Density Exchange Encoding (ADX) Encoding Academy Printing Density (APD) Values.pdf

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1、 Approved Copyright 2012 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved March 12, 2012 Table of Contents Page Foreword . 2 Intellectual Property 2 Introduction . 2 1 Scope . 3 2 Conformance Notation . 3 3 Normative References

2、 . 3 4 Terms and Definitions 4 5 Academy Density Exchange Encoding 4 Annex A Bibliography (Informative) . 8 Page 1 of 8 pages SMPTE ST 2065-3:2012SMPTE STANDARD Academy Density Exchange Encoding (ADX) Encoding Academy Printing Density (APD) Values SMPTE ST 2065-3:2012 Page 2 of 8 pages Foreword SMPT

3、E (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 over 80 countries on six continents. SMPTEs Engineering Documents, including Standards,

4、Standards 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 with other standards-developing organizations, including ISO, IEC and ITU. SMPTE Engineering Document

5、s are drafted in accordance with the rules given in Part XIII of its Administrative Practices. SMPTE ST 2065-3 was prepared by Technology Committee 10E. Intellectual Property At the time of publication no notice had been received by SMPTE claiming patent rights essential to the implementation of thi

6、s standard. 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 all such patent rights. Introduction This section is entirely informative and does not form an integra

7、l part of this Engineering Document. Academy Density Exchange Encoding (ADX) is an encoding of motion picture film color negative and internegative image data as Academy Printing Density (APD) values. ADX values encode image data as the APD printing density values of a color negative film designed t

8、o be printed on Kodak Visionfamily, Fujifilm Eternafamily, and Fujifilm F-CPcolor print films. It is expected that ADX will primarily be used to encode image data represented by the APD printing density values, or an approximation of the APD printing density values, from scanned film. The ADX equati

9、ons specified in this document provide conversions from APD values to digital code values as 10-bit or 16-bit integer color components. This document also specifies the method for converting between the 16-bit and 10-bit component value encoding metrics. Most color negative and internegative films r

10、equire no transformation in order to be compatible with the ADX encoding method, because most color negative and internegative films can be printed onto contemporary motion picture color print films with reasonable results. Color interpositive films are also compatible with the ADX encoding method a

11、s they are part of the negative reproduction chain. Some film stocks, such as scan-only color negative film (e.g. Eastman Kodak5299) and color print films, were not designed to be printed onto color print films. Printing a scan-only negative or color print film onto a contemporary motion picture col

12、or print film is not likely to yield a result that would be considered “good-looking.” Scanned density values from these materials require additional transformation, not covered by this specification, in order to achieve compatibility with the ADX encoding method. SMPTE ST 2065-3:2012 Page 3 of 8 pa

13、ges 1 Scope This Standard defines the Academy Density Exchange Encoding (ADX) including the encoding method, the 16-bit and 10-bit component value encoding metrics, and the method for converting between the 16-bit and 10-bit component value encoding metrics. 2 Conformance Notation Normative text is

14、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 editorially without affecting i

15、nteroperability. 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“ and “shall not“ indicate

16、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 excluding others; or that a certai

17、n 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 document. The keyword “reserved”

18、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. 3 Normative References The following standards contain provision

19、s which, through reference in this text, constitute provisions 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 r

20、ecent edition of the standards indicated below. SMPTE ST 2065-2:2012, Academy Printing Density (APD) Spectral Responsivities and Reference Measurement Device SMPTE ST 2065-3:2012 Page 4 of 8 pages 4 Terms and Definitions For the purposes of this document, the following terms and definitions apply. 4

21、.1 Academy Density Exchange Encoding (ADX): encoding of motion picture film color negative and internegative image data as APD. 4.2 Dmin: optical density of an area of a chemically processed photographic medium that has received zero exposure. Dmin corresponds to the optical density of film base and

22、 non-image density due to factors other than exposure to light. 4.3 scan-only color negative film: negative color photographic film primarily designed to be scanned by a motion picture film scanning device rather than printed on any photographic print medium. 4.4 transmittance factor: ratio of the m

23、easured flux transmitted by a specimen to the measured flux when the specimen is removed from the sampling aperture of the measuring device. 5 Academy Density Exchange Encoding 5.1 Specification The ADX equations specified in this section provide conversions from APD values to digital code values as

24、 10-bit or 16-bit integer color components. 5.1.1 Encoding Method ADX values shall encode image data as the APD values of a color negative film designed to be printed on contemporary motion picture color print films. Note: Contemporary motion picture color print films include Kodak Vision family, Fu

25、jifilm Eterna family, and Fujifilm F-CP color print films. 5.1.2 Encoding Metric The encoding data metric for the ADX shall be based on Dminsubtracted APD values. In the equations given below APDR, APDG,and APDB shallrepresent the red, green, and blue APD values respectively to be encoded. APDR_Dmin

26、,APDG_Dmin, and APDB_Dminshallrepresent the red, green, and blue APD values respectively of the assumed or measured Dmin of the sample. Note: Printing density values are always non-negative, as a value of 0 represents 100% transmission. Two component value encodings are specified (ADX16 andADX10). I

27、n ADX16each of the R, G, and B printing density values shall be stored as 16-bit unsigned integers. In ADX10each of the R, G, and B printing density values shall be stored as 10-bit unsigned integers. The 16-bit component value encoding metric (i.e. ADX16) shall allocate 2 bits of additional range a

28、nd 4 bits of additional precision as compared to the 10-bit component value encoding metric (i.e. ADX10). The 2 bits of additional range shall be allocated in the most significant bits. The 4 bits of additional precision shall be allocated in the least significant bits. Figure 1 illustrates the allo

29、cation of the additional bits in the 16-bit component value encoding metric as compared to the 10-bit component value encoding metric. SMPTE ST 2065-3:2012 Page 5 of 8 pages Figure 1 Bit allocations of ADX10 and ADX165.1.2.1 ADX16 The 16-bit Component Value Encoding Metric The ADX 16-bit component v

30、alue encoding metric shall be known as ADX16 or ADX16 where the use of subscripted text is not possible. ADX16code values shall be 16-bit unsigned integer values. The value range for ADX16shall be 0, 65535. ADX16code values shall be transformed from APD values using Equation 1. ADX16_R, ADX16_G,and

31、ADX16_B shall represent the red, green, and blue ADX16values respectively. ADX16_RMAX 0,MIN 65535,INT 1.00 APDR APDR _Dmin 80001520ADX16_G MAX 0,MIN 65535,INT 0.92 APDG APDG _Dmin 80001520ADX16_B MAX 0,MIN 65535,INT 0.95 APDB APDB _Dmin8000 1520Equation 1 where the INT operator returns the value of

32、0 for fractional parts in the range of 0 to .4999 and +1 for fractional parts in the range .5 to .9999, i.e. it rounds up fractions equal to or greater than 0.5, the MIN(a,b) operator returns the value of a if a=b, and the MAX(a,b) operator returns the value a if ab and b if a=b, and the MAX(a,b) op

33、erator returns the value a if ab and b if a 4) SMPTE ST 2065-3:2012 Page 8 of 8 pages Annex A Bibliography (Informative) Academy of Motion Picture Arts and Sciences (A.M.P.A.S.) Specification S-2008-002, Academy Density Exchange Encoding (ADX) and the Spectral Responsivities Defining Academy Printing Density (APD)