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1、Part 14 Grayscale Standard Display Function DICOM Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,
2、- Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- - Standard - PS 3.14-2004 Digital Imaging and
3、Communications in Medicine (DICOM) Part 14: Grayscale Standard Display Function Published by National Electrical Manufacturers Association 1300 N. 17th Street Rosslyn, Virginia 22209 USA Copyright 2004 by the National Electrical Manufacturers Association. All rights including translation into other
4、languages, reserved under the Universal Copyright Convention, the Berne Convention or the Protection of Literacy and Artistic Works, and the International and Pan American Copyright Conventions. Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=N
5、ASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 2 NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in th
6、e development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this document. NEMA standards and guideline publications, of which the document contained herein is on
7、e, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in t
8、he development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injur
9、y, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, expressed or implied, as to t
10、he accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or
11、 services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone
12、 using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available
13、 from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or inst
14、allations for safety or health purposes. Any certification or other statement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. Copyright National Electrical Manuf
15、acturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 3 Table of Contents NOTICE AND DISCLAIMER2 Table of Contents.3 F
16、OREWORD5 1. Scope and Field of Application .6 2. Normative References 6 3. Definitions .6 4. Symbols and Abbreviations 8 5. Conventions8 6. Overview .8 7 The Grayscale Standard Display Function11 7.1 GENERAL FORMULAS 12 7.2 TRANSMISSIVE HARDCOPY PRINTERS.13 7.3 REFLECTIVE HARDCOPY PRINTERS14 8 Refer
17、ences14 Annex A (INFORMATIVE) A DERIVATION OF THE GRAYSCALE STANDARD DISPLAY FUNCTION .16 A.1. RATIONALE FOR SELECTING THE GRAYSCALE STANDARD DISPLAY FUNCTION16 A.2. DETAILS OF THE BARTEN MODEL 17 A.3. REFERENCES19 Annex B (INFORMATIVE) TABLE OF THE GRAYSCALE STANDARD DISPLAY FUNCTION .21 Annex C (I
18、NFORMATIVE) MEASURING THE ACCURACY WITH WHICH A DISPLAY SYSTEM MATCHES THE GRAYSCALE STANDARD DISPLAY FUNCTION.28 C.1. GENERAL CONSIDERATIONS REGARDING CONFORMANCE AND METRICS 28 C.2. METHODOLOGY29 C.3. REFERENCES .31 Annex D (INFORMATIVE) ILLUSTRATIONS FOR ACHIEVING CONFORMANCE WITH THE GRAYSCALE S
19、TANDARD DISPLAY FUNCTION32 D.1 EMISSIVE DISPLAY SYSTEMS.32 D.1.1 Measuring the system Characteristic Curve 32 D.1.2 Application of the Standard Formula37 D.1.3 Implementation of the Standard37 D.1.4 Measures of Conformance.40 D.2 TRANSPARENT HARDCOPY DEVICES.41 D.2.1 Measuring the system Characteris
20、tic Curve .41 D.2.2 Application of the Grayscale Standard Display Function.42 D.2.3 Implementation of the Grayscale Standard Display Function43 D.2.4. Measures of Conformance.46 D.3 REFLECTIVE DISPLAY SYSTEMS 47 D.3.1. Measuring the system Characteristic Curve .48 D.3.2. Application of the Grayscale
21、 Standard Display Function48 D.3.3 Implementation of the Grayscale Standard Display Function48 D.3.4 Measures of Conformance.51 Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:
22、24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 4 Annex E (INFORMATIVE) REALIZABLE JND RANGE OF A DISPLAY UNDER AMBIENT LIGHT54 Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical St
23、andards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 5 FOREWORD The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) formed a joint committee to develop a
24、standard for Digital Imaging and Communications in Medicine (DICOM). While other parts of the DICOM Standard specify how digital image data can be moved from system to system, it does not specify how the pixel values should be interpreted or displayed. PS 3.14 specifies a function that relates pixel
25、 values to displayed Luminance levels. A digital signal from an image can be measured, characterized, transmitted, and reproduced objectively and accurately. However, the visual interpretation of that signal is dependent on the varied characteristics of the systems displaying that image. Currently,
26、images produced by the same signal may have completely different visual appearance, information, and characteristics on different display devices. In medical imaging, it is important that there be a visual consistency in how a given digital image appears, whether viewed, for example, on the display
27、monitor of a workstation or as a film on a light-box. In the absence of any standard which regulates how these images are to be visually presented on any device, a digital image which has good diagnostic value when viewed on one device could look very different and have greatly reduced diagnostic va
28、lue when viewed on another device. Accordingly, PS 3.14 was developed to provide an objective, quantitative mechanism for mapping digital image values into a given range of Luminance. An application which knows this relationship between digital values and display Luminance can produce better visual
29、consistency in how that image appears on diverse display devices. The relationship that PS 3.14 defines between digital image values and displayed Luminance is based upon measurements and models of human perception over a wide range of Luminance, not upon the characteristics of any one image present
30、ation device or of any one imaging modality. It is also not dependent upon user preferences, which can be more properly handled by other constructs such as the DICOM Presentation Lookup Table. PS 3.14 was reviewed by other standardization organizations including CEN TC251 in Europe and JIRA in Japan
31、, and by other organizations including IEEE, HL7, and ANSI in the USA. PS 3.14 was developed according to NEMA procedures. PS 3.14 is structured using the guidelines established in the following document: ISO/IEC Directives, 1989 Part 3 : Drafting and Presentation of International Standards. Copyrig
32、ht National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 6 1. Scope and Field of Application
33、PS 3.14 specifies a standardized Display Function for display of grayscale images. It provides examples of methods for measuring the Characteristic Curve of a particular Display System for the purpose of either altering the Display System to match the Grayscale Standard Display Function, or for meas
34、uring the conformance of a Display System to the Grayscale Standard Display Function. Display Systems include such things as monitors with their associated driving electronics and printers producing films which are placed on light-boxes or alternators. PS 3.14 is neither a performance nor an image d
35、isplay standard. PS 3.14 does not define which Luminance and/or Luminance Range or optical density range an image presentation device must provide. PS 3.14 does not define how the particular picture element values in a specific imaging modality are to be presented. PS 3.14 does not specify functions
36、 for display of color images, as the specified function is limited to the display of grayscale images. Color Display Systems may be calibrated to the Grayscale Standard Display Function for the purpose of displaying grayscale images. . 2. Normative References The following standards contain provisio
37、ns 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 possibilities of applying the mos
38、t recent editions of the standards indicated below. ISO/IEC Directives, 1989 Part 3 - Drafting and presentation of International Standards. 3. Definitions For the purposes of PS 3.14 the following definitions apply. Characteristic Curve: The inherent Display Function of a Display System including th
39、e effects of ambient light. The Characteristic Curve describes Luminance versus DDL of an emissive display device, such as a CRT/display controller system, or Luminance of light reflected from a print medium, or Luminance derived from the measured optical density versus DDL of a hard-copy medium and
40、 the given Luminance of a light-box. The Characteristic Curve depends on operating parameters of the Display System. Note: The Luminance generated by an emissive display may be measured with a photometer. Diffuse optical density of a hard-copy may be measured with a densitometer. Contrast Sensitivit
41、y characterizes the sensitivity of the average human observer to Luminance changes of the Standard Target. Contrast Sensitivity is inversely proportional to Threshold Modulation. Contrast Threshold: A function that plots the Just-Noticeable Difference divided by the Luminance across the Luminance Ra
42、nge. Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMALicensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/19/2007 08:24:16 MDTNo reproduction or networking permitted without license from IHS -,-,- PS 3.14 -2004 Page 7 Digital Driving Level
43、(DDL): A digital value which given as input to a Display System produces a Luminance. The set of DDLs of a Display System is all the possible discrete values that can produce Luminance values on that Display System. The mapping of DDLs to Luminance values for a Display System produces the Characteri
44、stic Curve of that Display System. The actual output for a given DDL is specific to the Display System and is not corrected for the Grayscale Standard Display Function. Display Function: A function that describes a defined grayscale rendition of a Display System, the mapping of the DDLs in a defined
45、 space to Luminance, including the effects of ambient light at a given state of adjustment of the Display System. Distinguished from Characteristic Curve, which is the inherent Display Function of a Display System. Display System: A device or devices that accept DDLs to produce corresponding Luminan
46、ce values. This includes emissive displays, transmissive hardcopy viewed on light boxes, and reflective hardcopy. Illuminance: Light from the environment surrounding the Display System which illuminates the display medium. It contributes to the Luminance that is received by an observer from the imag
47、e display. Ambient Light reduces the contrast in the image. Just-Noticeable Difference (JND): The Luminance difference of a given target under given viewing conditions that the average human observer can just perceive. JND Index: The input value to the Grayscale Standard Display Function, such that
48、one step in JND Index results in a Luminance difference that is a Just-Noticeable Difference. Luminance is the luminous intensity per unit area projected in a given direction. The Systme Internationale unit (used in PS 3.14) is candela per square meter (cd/m2), which is sometimes called nit. Another unit often used is footlambert (fL). 1 fL = 3.426 cd/m2. Luminance Range: The span of Luminance values of a Display System from a minimum Luminance to a maximum Luminance. P-Value: A device independent value defined in a perceptually l