1、Designation: D7298 06 (Reapproved 2017)Standard Test Method forMeasurement of Comparative Legibility by Means ofPolarizing Filter Instrumentation1This standard is issued under the fixed designation D7298; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides an objective means to com-paratively measure the ease of r
3、eading printed matter for use inpackage labeling.1.2 This test method is not intended to quantify the legibilityof a printed item against a standard but to compare its legibilityagainst other items.1.3 This test method uses human subjects to view printedmatter mounted in a specialized instrument.1.4
4、 The user of this test method must be aware that resultsmay differ from one age group of subjects to another.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
5、 and health practices and determine the applica-bility of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Stan
6、dards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D996 Terminology of Packaging and Distribution Environ-ments3. Terminology3.1 DefinitionsTerms and definitions used in this testmethod may b
7、e found in Terminology D996.3.2 Definitions of Terms Specific to This Standard:3.2.1 age groupsubjects are grouped by ages in a specifiedrange.3.2.2 analyzera moveable polarizing filter; the subjectoperates a hand wheel to rotate the analyzer (see Fig. 1 and Fig.2).3.2.3 degrees of rotationthe angle
8、 of rotation of theanalyzer where 0 is equivalent to no light transmission and 90is equivalent to full light transmission.3.2.3.1 DiscussionAt 0 rotation, the analyzer and polar-izer optical axes are perpendicular to one another.3.2.4 easellocated on top of the moveable stage; it is aplatform where
9、printed matter is placed to be read (see Fig. 1and Fig. 2).3.2.5 hand cranka crank located at the front of theinstrument that adjusts the distance of printed matter bymoving the stage and easel. When it is rotated clockwise, itmoves the moveable stage closer to the subject, and when it isrotated cou
10、nterclockwise it moves the stage away from thesubject (see Fig. 1 and Fig. 2).3.2.6 hand wheela wheel subjects turn to rotate theanalyzer. Counterclockwise rotation increases the light trans-mitted and raises the legibility index. Clockwise rotationdecreases the light transmitted (see Fig. 1 and Fig
11、. 2) andlowers the legibility index.3.2.7 legibilitythe ease of deciphering or reading printedmatter, as measured by the legibility index in this test method.3.2.8 legibility indexthe name given to the degrees ofrotation of the analyzer, the reporting unit for the measurementof legibility. The first
12、 point where the printed matter becomeseasy forthe subject to read.3.2.9 moveable stagea device topped with an easel that ismounted on a track within the legibility instrument that adjuststhe distance between the subject and the easel.3.2.10 polarizera fixed polarizing filter, mounted in theinstrume
13、nt (see Fig. 1 and Fig. 2).3.2.11 subjectthe person viewing the printed matter in theinstrument and controlling the rotation of the analyzer.3.2.12 testerthe person conducting the experiment.1This test method is under the jurisdiction of ASTM Committee F02 on PrimaryBarrier Packaging and is the dire
14、ct responsibility of Subcommittee F02.50 onPackage Design and Development.Current edition approved Dec. 15, 2017. Published January 2018. Originallyapproved in 2006. Last previous edition approved in 2011 as D7298 06 (2011)1.DOI: 10.1520/D7298-06R17.2For referenced ASTM standards, visit the ASTM web
15、site, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Stat
16、esThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Tra
17、de (TBT) Committee.13.2.13 training referenceAstandard message created in an8 point font. Subjects view the training reference before datacollection begins so that they become accustomed to theinstrument without affectingtest results.NOTE 1*Analyzer and polarizer are actually just inside the front w
18、all of the instrument; subject looks through them using a shielded eyepiece (Seephoto in Fig. 2). They are shown in the schematic to give researchers a clear idea of the instruments construction.FIG. 1 Schematic of the Legibility InstrumentFIG. 2 Photo of Legibility InstrumentD7298 06 (2017)24. Summ
19、ary of Test Method4.1 This test method describes a means for evaluating thelegibility of printed matter such as package labeling, printedinserts, and carton graphics by defining a standard procedurefor measuring the comparative legibility of printed matterunder consistent, controlled light condition
20、s by the use of aspecialized instrument.5. Significance and Use5.1 This test method assists in evaluating the effect oflayout, typeface, type size, color, and background on thelegibility of printed matter.5.2 Previous research3has shown that results are moresignificantly impacted by subject age than
21、 any other effect.Older subjects tend to require more light when using thisinstrument. Because subjects age at different rates as a result oflifestyle and genetics, variability of data tends to increase withincreasing age. This test method was developed using subjectsof ages 19 to 28 years. It is ad
22、vised that subjects age 19 to 28be used in cases where variability needs to be kept to aminimum.5.3 Testers can compare legibility between various groupsof subjects (by age, light intensity, distance, vision character-istics of the subjects) and one against other label configurationswithin groups of
23、 subjects6. Apparatus6.1 The legibility instrument4(see Fig. 1 and Fig. 2)isarectangular structure designed to minimize light leakage and toprovide an internal platform to hold printed matter to be tested.6.2 The interior shall have a gray or black matte surface tominimize internal light reflection.
24、6.3 An end panel shall have a polarizer and an analyzermounted in its center, controlled by a hand wheel (see Fig. 1).6.4 The analyzer is capable of being rotated to a maximumof 90 (relative to the polarizer). This rotation allows the filtersto go from total light blockage to full light transmission
25、(sensitivity is to be 0.1 of rotation).6.5 The instrument shall have a moveable stage. On top ofthe moveable stage is an easel that is angled so its surface andthe surface of the filter are parallel (see Fig. 1 and Fig. 2). Theeasel holds the reference copy.6.5.1 The stage is capable of moving from
26、a distance of 15in. (38 cm) from the subjects eyes to a distance of 22 in. (56cm) from subjects eyes.6.5.2 A hand crank on the front panel of the instrument isused to move the stage.6.5.3 Two incandescent flood lamps, capable of achievingthe desired light level, shall illuminate the instruments inte
27、rior.Light is projected toward the easel, and is controlled by arheostat. The instrument should be constructed so that theangle of the light source relative to the easel does not produceglare.6.5.4 The instrument shall have a light sensor, whichmeasures the illumination incident on the easel.6.5.5 T
28、he instrument shall have an eye shield to position thetest subjects eyes and shield the filters from ambient light.6.5.6 The instrument is not capable of accommodating theheight of the subject. Chair height shall be adjustable by thesubject.7. Equipment Controls and Monitors7.1 Analyzer rotation con
29、trol (hand wheel), capable ofrotating the analyzer through a full 90, from total lightblockage to full transmission.7.2 Analyzer rotation measurement (readout of legibilityindex), having a sensitivity of 0.1.7.3 Rheostat, capable of providing variable light levels.7.4 Built-in light sensor (readout
30、of light level), a digitalreadout instrument capable of measuring light levels to 0.1 fc.7.5 Stage distance, measurable to an accuracy of 61cm(0.4 in.).8. Procedure8.1 Using the hand crank, the tester adjusts the moveablestage so that the distance from the easel to the subjects eyesfalls between 16
31、in. (41 cm) and 20 in. (51 cm).8.2 The tester shall measure and record the visual acuity ofthe subject, using a near distance visual acuity card with theSnellen visual acuity5scale.8.3 The tester shall record the subjects gender and age8.4 The tester rotates the analyzer to a position of 0 ofrotatio
32、n (so that no light passes through).8.5 With the door of the instrument closed, the rheostat isused by the tester to adjust the light level inside the instrumentto 25 6 1 fc.8.6 The tester places the training reference onto the easel.8.6.1 The reference should be flat against the easel and notcurled
33、.8.7 The subject is instructed by the tester to wear anyeyewear that they would normally use to read package labelsand to look into the eye shield, and allow time for his/her eyesto adjust. It is important to note that some subjects that wear bior tri-focals may have difficulty using the instrument.
34、8.7.1 Any corrective eyewear that is used by the subject willbe recorded.8.8 The tester instructs the subject to rotate the hand wheelcounterclockwise “until the first point that the subject caneasily read printed matter without straining their eyes.”8.9 The tester records the legibility index, the
35、degrees ofrotation required by the subject.3Bix, L., Gilliland, D., Chen, B., and Sung, H., from unpublished file, “Using thePolariscope as a Measure of Legibility,” December,1997.4Information presented here was based on the Lockhart Legibility Instrument, aninstrument developed by Dr. Hugh Lockhart
36、 at Michigan State University. Forfurther information, contact Hugh Lockhart at lckhrtmsu.edu.520/20, 20/30, 20/40, 20/50, 20/60, 20/80, 20/100, 20/200.D7298 06 (2017)38.9.1 This value will not be reported, but is recorded so thatsubjects are not aware that it is a training reference.8.10 The tester
37、 returns the analyzer to the 0 (no lighttransmission) position.8.11 Steps 8.6 8.9 are repeated for a second trainingreference. An analysis of residuals3revealed that the first tworeadings using this instrument tended to be higher than thosethat followed, due to an “adjustment period” as people becam
38、eaccustomed to the instrument. As a result of this finding, theuse of two training references per test has been included in thistest method.8.12 The tester places the printed matter onto the stage.8.12.1 The test material should be flat against the stage andnot curled.8.13 The subject is instructed
39、by the tester to look into theeye shield, and allow time for the eyes to adjust. (See 8.7.)8.14 The tester instructs the subject to rotate the hand wheelcounterclockwise “until the first point that the subject caneasily read the printed matter without straining their eyes.”8.15 The tester records th
40、e degrees of rotation required bythe subject as the legibility index.8.16 The tester returns the analyzer to the 0 (no lighttransmission) position.8.17 Steps 8.11 8.15 are repeated until the test material isexhausted. Research to date indicates that subjects can affectresults by “learning” the messa
41、ge. Therefore, experimentaldesign should be carefully considered to eliminate the learningeffect.9. Report9.1 The report shall contain the age range of each test groupand the subjects ages within each group.9.2 The report shall contain the mean legibility index.9.3 The report shall contain the stand
42、ard deviation.9.4 The report shall contain the test location, test date, andtime of day.9.5 The subjects visual acuity and gender shall also berecorded.9.6 The subjects use of eyewear, and the type of eyewear,shall be recorded.9.7 Any deviations from this test method must be noted inthis report.10.
43、Precision and Bias10.1 Precision:10.1.1 Because there is only one legibility instrument,results presented in this precision statement represent standarddeviations obtained from subjects tested at Michigan StateUniversity only.10.1.2 Six cards were measured by 19 subjects to develop astatement regard
44、ing precision. Each card was printed in 10point Helvetica Light using a Hewlett Packard 722 Ink Jetprinter. Each card contained a different message; messages hadbeen shown in previous studies to have statistically marginal6or insignificant effect7at =0.05. Messages were printed in ablack on white co
45、ntrast and were centered ona3by4in.indexcard. Test matter as large as approximately 12 in. across and 8in. high has been measured using this instrument. It is advisedthat test matter no larger than this be tested.10.1.3 Viewing distance from the subject to the card wasfixed at 18.5 in. and subjects
46、were asked to rotate the handleuntil the first point that they could “easily read the words on thecards without straining their eyes.”10.1.4 The coefficient of variation across all subjects and allmessages was 47.6 %. Coefficients of variation are muchsmaller when they are examined on a per subject
47、basis (see Fig.1). When the coefficients are measured between subjects, asreported here, they are much larger. It is important to note thatmuch of the variability of observations is attributable to thedifferences in subjects themselves. It is for this reason thatusing narrow age ranges when testing
48、is advised.10.1.5 The graph in Fig. 3 shows the coefficients of varia-tion by subject, across all six messages.10.2 BiasThe bias for this test method has not beendetermined because there is no know reference available.11. Keywords11.1 analyzer; label; legibility; legibility index; light level;polari
49、zer; test6Bix, L., “The Effect of Subject Age on Legibility,” Masters Thesis, MichiganState University, 1998.7Lockhart, H. and Bix, L. from unpublished file, “Color Contrast Studies,” 1996.D7298 06 (2017)4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their o
