1、Designation: D7298 06 (Reapproved 2011)1Standard 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.1NOTEMinor editorial corrections were made to Sections 3.2.5, 3.2.6, and 7.3 in April 2011.1. S
3、cope1.1 This test method provides an objective means to com-paratively measure the ease of reading 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 t
4、est method uses human subjects to view printedmatter mounted in a specialized instrument.1.4 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 it
5、s 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:2D996 Terminology of Packaging and Distribution Environ-ments3. Terminol
6、ogy3.1 DefinitionsTerms and definitions used in this testmethod may be found in Terminology D996.3.2 Definitions of Terms Specific to This Standard:3.2.1 age groupsubjects are grouped by ages in a speci-fied range.3.2.2 analyzera moveable polarizing filter; the subjectoperates a hand wheel to rotate
7、 the analyzer (see Fig. 1 and Fig.2).3.2.3 degrees of rotationthe angle 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.
8、3.2.4 easellocated on top of the moveable stage; it is aplatform where 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, itmo
9、ves the moveable stage closer to the subject, and when it isrotated counterclockwise 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
10、. Clockwise rotation1This test method is under the jurisdiction of ASTM Committee D10 onPackaging and is the direct responsibility of Subcommittee D10.32 on Consumer,Pharmaceutical and Medical Packaging.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 2006. Last pr
11、evious edition approved in 2006 as D7298 06. DOI:10.1520/D7298-06R11E01.2For 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 AS
12、TM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.decreases the light transmitted (see Fig. 1 and Fig. 2) andlowers the legibility index.3.2.7 legibilitythe ease of deciphering or reading printedmatter, as measured by the le
13、gibility 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 point where the printed matter becomeseasy forthe subject to read.NOTE 1*Analyzer and polarizer are actually just inside t
14、he front wall 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 (201
15、1)123.2.9 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 theinstrument (see Fig. 1 and Fig. 2).3.2.11 subjectthe person viewing the
16、 printed matter in theinstrument and controlling the rotation of the analyzer.3.2.12 testerthe person conducting the experiment.3.2.13 training referenceA standard message created inan 8 point font. Subjects view the training reference before datacollection begins so that they become accustomed to t
17、heinstrument without affectingtest results.4. Summary 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
18、matterunder consistent, controlled light conditions 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
19、are moresignificantly impacted by subject age than 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 develo
20、ped using subjectsof ages 19 to 28 years. It is advised 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
21、against other label configurationswithin groups of 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 m
22、atte surface tominimize internal light reflection.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 fr
23、om total light blockage to full light transmission(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 referen
24、ce copy.6.5.1 The stage is capable of moving from 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
25、light level, shall illuminate the instruments interior.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, whichmeasu
26、res the illumination incident on the easel.6.5.5 The 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. Equipm
27、ent Controls and Monitors7.1 Analyzer rotation control (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 variabl
28、e light levels.7.4 Built-in light sensor (readout 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 fr
29、om the easel to the subjects eyesfalls between 16 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
30、 rotates the analyzer to a position of 0 ofrotation (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 refere
31、nce should be flat against the easel and notcurled.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 tr
32、i-focals may have difficulty using the instrument.8.7.1 Any corrective eyewear that is used by the subject willbe recorded.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
33、 the Lockhart Legibility Instrument, aninstrument developed by Dr. Hugh Lockhart 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 (2011)138.8 The tester instructs the subject to rotate the
34、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 degrees ofrotation required by the subject.8.9.1 This value will not be reported, but is recorded so thatsubjects are not aw
35、are that it is a training reference.8.10 The tester returns the analyzer to the 0 (no lighttransmission) position.8.11 Steps 8.6-8.9 are repeated for a second training refer-ence. An analysis of residuals3revealed that the first tworeadings using this instrument tended to be higher than thosethat fo
36、llowed, due to an “adjustment period” as people becameaccustomed 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 th
37、e stage andnot curled.8.13 The subject is instructed 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 wit
38、hout straining their eyes.”8.15 The tester records the 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 th
39、at subjects can affectresults by “learning” the message. 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 le
40、gibility index.9.3 The report shall contain the standard 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 f
41、rom this test method must be noted inthis report.10. 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
42、 measured by 19 subjects to develop astatement regarding 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 effect7
43、at a=0.05. Messages were printed in ablack on white contrast 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
44、subject to the card wasfixed at 18.5 in. and subjects 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 ar
45、e muchsmaller when they are examined on a per subject 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
46、 this reason thatusing narrow age ranges when testing 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; l
47、abel; legibility; legibility index; light level;polarizer; 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 (2011)14ASTM International takes no position res
48、pecting 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 own responsibility.This
49、standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known t
