1、Designation: E 2545 07Standard Test Method forObjective Measurement of Gingival Color Using Digital StillCameras1This standard is issued under the fixed designation E 2545; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe color of gingiva is an important parameter used to ascertain certain medical and estheticinformation. RGB color
3、 values for gingiva are derived from the native signals generated by a digitalstill camera, DSC, by broadband measurement of the reflectance of gingiva. This test method, E 2545,specifies the procedure used for the color measurement of gingival color at 45 relative to the sampleplane containing the
4、gingiva under a nearly equal energy illuminating at 45 and viewing at 0. Thismethod is appropriate for evaluating the color of facial gingiva.1. Scope1.1 This test method covers the procedure, instrumentalrequirements, standardization procedures, material standards,measurement procedures, and parame
5、ters necessary to makeprecise measurements of gingival color. In particular it ismeant to measure the color of gingiva in human subjects.1.2 Digital images are used to evaluate gingival color on thefacial labial or buccal surfaces of the gingiva. The marginalgingival tissue adjacent to natural teeth
6、 may be of particularinterest for analysis.All other non-relevant parts; such as teeth,tongue, spaces, dental restorations or prostheses, etc., must beseparated from the measurement and the analysis.All localizeddiscoloration; such as stains, inclusions, pigmentations, etc.,may be separated from the
7、 measurement and the analysis.1.2.1 The broadband reflectance factors of gingiva and thesurrounding tissue are measured. The colorimetric measure-ment is performed using an illuminator(s) that provides con-trolled illumination on the gingiva using a digital still camerato capture the digital image.1
8、.3 Data acquired using this test method may be used toassess personal gingival color for the purposes of identifyingoverall health status, health status at specific sites in the mouth,or to track changes in personal health status for individualsover time. Pooled data may be used to assess gingival c
9、olor,health and disease among populations in epidemiologicalsurveys, evaluation of comparative product efficacy, or safetyand treatment response in clinical trials involving gingivalhealth or disease.1.4 The apparatus, measurement procedure, and data analy-sis technique are generic, so that a specif
10、ic apparatus, measure-ment procedure, or data analysis technique may not be ex-cluded.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associat
11、ed with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 179 Guide for Selection of Geometric Conditions forMeasurem
12、ent of Reflection and Transmission Properties ofMaterialsE 284 Terminology of AppearanceE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE 1767 Practice for Specifying th
13、e Geometries of Observa-tion and Measurement to Characterize the Appearance ofMaterials1This test method is under the jurisdiction of ASTM Committee E12 on Colorand Appearance and is the direct responsibility of Subcommittee E12.06 on ImageBased Color Measurement.Current edition approved May 1, 2007
14、. Published July 2007.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 ISO Publications:3ISO 173211 Colour characterization of digital still cam-eras (DSCs) Part 1: Stimuli, metrology, and testproceduresISO/IEC 15441:2000 JPEG2000 Information technology JPEG 2000 image coding system Part 1:
16、 Core codingsystem, commonly known as JPEG 2000 jp2 file format2.3 ISCC Publications:4Technical Report 20031 Guide to Material Standards andTheir Use in Color Measurement2.4 Other Publications:5TIFF Tagged Image File Format3. Terminology3.1 Terms and definitions in Terminology E 284 are appli-cable
17、to this test method.3.2 Definitions: Terms included in this section are peculiarto this standard.3.2.1 angle of incidence, nu1and optional u2, the polarangle between the central ray of the illuminator(s), I1and I2,and the Z axis which is the optical axis of the camera.3.2.1.1 DiscussionThese are sho
18、wn in Fig. A1.1.3.2.2 bit depth, nthe number of digital bits used to storeinformation contained in each color channel of each pixel.3.2.2.1 DiscussionThe bit depth determines the maximumnumber of colors that may be encoded by the system. Forexample, a 24 bit system comprising 8 bits per channel cane
19、ncode 28by 28by 28or about 17 million; colors far more thanare distinguishable by the human observer.3.2.3 facial surfaces, nthe surfaces of teeth and gingivathat are oriented outward toward the lips (labial) and cheeks(buccal), and facing away from the tongue or roof of themouth.3.2.4 gingivitis, n
20、inflammation of the marginal gingiva inresponse to dental plaque accumulation on adjacent toothsurfaces.3.2.5 in-vivoadj, or adv, within a living body.3.2.5.1 DiscussionUsed to describe measurements madein a living body.3.2.6 polarization, nthe process by which vibrations oflight are given a definit
21、e orientation; also the state produced bythat process.3.2.7 polarizing filter, na component that blocks one ofthe two planes of vibration of an electromagnetic wave, thusproducing linearly polarized light.4. Summary of Test Method4.1 This test method describes the procedures for broadbandreflectomet
22、ry of gingival tissue. The standardization of theinstrument used to measure the tissue is defined. The images ofartifact standards and samples are captured with a DSC. TheRGB values of these images are read and stored. The results arereported as RGB values and can be converted to othercolorimetric c
23、oordinates such as CIELAB. Procedures forconverting the RGB camera values to component CIELABvalues are also presented.5. Significance and Use5.1 The color of gingiva or changes in gingival color can beobserved. The light reflected from the facial surfaces of thegingiva can be used to calculate colo
24、r coordinates. These datareveal information about the efficacy of a product, treatmentstudied, or epidemiology of anti-gingivitis treatments. Forexample, clinical studies of gingivitis treatment systems evalu-ate the efficacy of manufacturers products.5.2 The change in color of the facial surface gi
25、ngiva can beused to determine and optimize the efficacy of anti-gingivitistreatments. For example, the data can provide the answer to thequestion: “What product or system is the most efficacious inthe treatment of gingivitis?”5.3 Chronic inflammatory disease of the gingiva and peri-odontium results
26、in destruction of gingival connective tissue,periodontal ligament, and alveolar bone. Clinically, inflamma-tion is seen as redness, swelling, and bleeding observed uponprobing.5.4 This procedure is suitable for use in diagnosis andmonitoring, research and development, epidemiological orother surveys
27、, marketing studies, comparative product analy-sis, and clinical trials.5.5 Popular methods assess gingival inflammation via re-peated clinical examination of the gingival tissues.6,7Thesemethods typically quantify gingival color, which are used toassess gingival health or disease, at multiple intra
28、oral sites onthe gingiva using a simple non-linear scoring system or index.Assessment of gingival color is an important component ofhealth status for mild-to-severe gingival disease. These tech-niques are time-consuming, subjective, and often invasive, andfor archival purposes, separate intraoral ph
29、otographs must becollected to document gingival color and appearance. Variationbetween and among examiners may contribute to appreciabledifferences in measurement.86. Interferences6.1 The interferences identified below may be eliminatedand problems avoided by controlling and regulating each factorwi
30、thin the constraints of the allowable experimental error. Thevalues and limits for these factors are typically determinedexperimentally. If the standard laboratory conditions listedbelow change during the test or from test to test by anappreciable amount, these conditions may cause interferences,and
31、 the accuracy and precision requirements of this test methodmay not be achieved. In some cases these effects may only beobserved during the performance of the test.3Available from International Imaging Industry Association (13A), 701Westchester Avenue, Suite 317W, White Plains NY 10604, www.13a.org.
32、4Available from ISSC, Inter-Society Color Council, 11491 Sunset Hills Rd.,Reston, VA 20190, www.iscc.org.5TIFF, Tagged Image File Format, Adobe Systems Incorporated, San Jose, CA,http:/.6Loe H., and Silness, J., “Prevalence and Severity,” Journal Peridontal Diseasein Pregnancy, I, Acta Odontologica
33、Scand , 1963, 21:533-551.7Lobene, R. R., Weatherford, T., Ross, N. M., Lamm, R.A., and Menaker, L., “Amodified gingival index for use in clinical trials,” Clinical Prevention Dentistry,1986, 8:36.8McClanahan, S. F., Bartizek, R. D., and Biesbrock, A. R., “Identification andconsequences of distinct L
34、oe-Silness gingival index examiner styles for the clinicalassessment of gingivitis,” Journal of Periodontology, 2001, 72:38392.E25450726.1.1 Factors Affecting Test ResultsThe following envi-ronmental factors are known to affect the test results.6.1.1.1 Extraneous RadiationLight including near infra-
35、red from sources other than the illuminator(s) must be shieldedfrom the test apparatus.6.1.1.2 VibrationsMechanical oscillations that causecomponents of the apparatus to move relative to one andanother may cause errors in test results.6.1.1.3 Thermal ChangesTemperature changes occurringduring a test
36、 or differences in temperature between testinglocations may affect the reflectance factor of the standardiza-tion, calibration, and verification plaques, and the apparatusspectral response function.6.1.1.4 Power Input FluctuationsLarge changes in theline frequency or supply voltage may cause the app
37、aratus toreport erroneous results6.1.2 RetractorsThe surface finish of the retractors affectsthe experimental test results. It has been determined that aglossy finish on the surface of the retractors may introduce abias into the test results.6.2 The system must allow for successful standardization.
38、Ifthe system cannot be standardized, a series of checks must beperformed (lighting, camera, etc.) to identify the reason. Thecomponent of the system in error will be adjusted or replacedto bring the system back into calibration.7. Apparatus7.1 GeneralThe components described in this section aredescr
39、ibed generically. The intention is not to exclude anycomponent from being used, or to exclude any type ofinstrument that may be available commercially. Between 4 and6 different components or component assemblies are requiredto accomplish the measurement.7.2 GeometryThe geometry of the system is 45:0
40、 asdescribed in Practice E 1767. The DSC System Geometry(Coordinate System) and Angular Convention are shown inFig. A1.1 included in Annex A1.7.3 ComponentsA block diagram of these componentassemblies is shown diagrammatically in Fig.A1.2, included inAnnex A1.7.3.1 Source Illumination AssemblyContai
41、ns the sourceof illumination and associated optics to produce irradiance, E,on the sample over a specified spot area, designated A. Thesource is broadband and continuous in nature. A diagrammaticrepresentation of the components of a typical source illumina-tion assembly Unit is shown in Fig. A1.3, i
42、ncluded in AnnexA1.7.3.2 Spectral Power DistributionThe light source shouldbe spatially uniform over the area of interest, and have aspectrum that approximates CIE Illuminant D50 over thespectral range of the DSC, a choice that is customary andachieves the uniformity of practice. Commonly used light
43、sources include incandescent lamps with filters to simulate astandard illuminant, flash xenon with filters, or white-LEDlamps to realize the approximate color temperature of 5000K.7.3.3 PolarizerThe linear polarizer provides and controlsthe polarization state of the incident light. This polarizer on
44、 theilluminators plus a cross polarizing filter on the lens system ofthe DSC eliminates glare caused by reflection of the subjectsgingiva tissue during imaging. Wavelength range, extinctionratio, transmittance, and beam deviation are important param-eters of the components and must be selected.7.3.4
45、 Heat Rejection FiltersThese filters remove undes-ired near infrared (IR) radiation including heat that adverselyaffects the subject, and provide spectral shaping of the spectralpower distribution of the source illumination7.3.5 Selective Blue FiltersThese filters condition thespectral power distrib
46、ution of the illumination so that thespectral power distribution is similar to Illuminant D50.7.3.6 Sample Plane HolderThe sample plane holder pro-vides a secure mount so that it positions the subjects incisorsnormal to the Z axis, and centered along the X and Y axes. Thismust be done so that the gi
47、ngival tissue is presented to the DSCin a repeatable and reproducible manner. The sample mountmust be kept unobtrusive so that it is “friendly” and notintimidating to the subjects. A chin rest is used to preciselyposition the subjects relative to the instrumentation (Fig. 1).The subjects place their
48、 chin on a chin rest which is aquarter-cup shaped rig, as shown in Fig. 2.7.3.6.1 Lip retractors9(Fig. 3) are used to expose themajority of the subjects gingiva to the DSC system. Subjects9Retractors with a matte finish have been found satisfactory for this purpose.FIG. 1 Subject Positioned in Instr
49、umentationFIG. 2 Chin RestE2545073hold their head straight, join the tips of their upper and lowerincisors together and place their tongue against the top of theirmouth. The facial surface of the central incisors should bealigned with a line marked on the chin rest indicating the centeralong the X axis.7.4 Detector Optical Elements:7.4.1 The typical detector optical elements are shown in Fig.A1.4, included in Annex A1.7.4.2 The linear cross polarizer provides and controls theplane of polarization, which is the plane spanned by t
