1、I BSI BS*ISO*7565 93 3624bb9 0393942 436 BRITISH STANDARD Implementation of IS0 7565 : 1993 Micrographics - Readers for transparent microforms - Measurement of characteristics 7565 : 1993 BS IS0 BSI BS*IS0*7565 93 3b24bb 0393943 372 BS IS0 7565 : 1993 National foreword This British Standard reproduc
2、es verbatim IS0 7565 : 1993 and implements it as the UK national standard. This British Standard is published under the direction of the Information and Documentation Standards Policy Committee whose Technical Committee DOT/16 has the responsibility to: - aid enquirers to understand the text; - pres
3、ent to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; - monitor related international and European developments and promulgate them in the UK. NUTE. International and European Standards, as well as overseas standards,
4、 are available from Customer Services, Publications, BSI, Linford Wood, Milton Keynes, MK14 6LE. Compliance with a British Standard does not of itself confer immunity from legal obligations. I NTERNATIONAL STANDARD IS0 7565 First edition 1993-09-01 Micrographics - Readers for transparent microforms
5、- Measurement of character ist ics Micrographie - Appareils de lecture de microformes - Mesurage des caractristiques Reference number IS0 7565:1993(E) BSI BS*ISO*75bS 93 = 1624bb 0371945 145 IS0 7565:1993(E) Contents Page 1 Scope 2 Normative references . 3 Definitions . 4 Magnification . 4.1 Apparat
6、us 4.2 Procedure . 5 Resolution 5.1 Test charts 5.2 Magnifier . 5.3 Procedure . 6 Geometric distortion 6.1 Test film 6.2 Procedure . 7 Screen luminance 7.1 General conditions 7.2 Procedure . 8 Screen contrast . 8.1 Apparatus 8.2 Screen contrast measurements . 9 Film gate temperature measurements . 9
7、.1 Apparatus 9.2 Procedure . 1 1 1 1 1 3 3 3 3 3 3 3 3 5 5 6 6 6 7 8 8 8 O IS0 1993 All rights reserved . No part of this publication may be reproduced or utilized in any form or by any means. electronic or mechanical. including photocopying and microfilm. without per- mission in writing from the pu
8、blisher . International Organization for Standardization Case Postale 56 CH-1 21 1 Genve 20 Switzerland Printed in Switzerland II BSI BS*IS0*7565 93 3b24669 039394b 081 IS0 7565:1993(E) Annexes A Importance of the luminance measurement . 9 A.l Screen characteristics 9 A.2 Screen observation 9 A.3 Ev
9、aluation of screen diffusion characteristics . 9 B Field method using a luxmeter 12 B.l Presentation . 12 B.2 Method . 12 . III BSI BS*ISO*75b5 73 M Lb24bb9 039L747 TL M IS0 7565:1993(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards
10、 bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organiza
11、tions, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circu
12、lated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard IS0 7565 was prepared by Technical Committee ISOflC 171, Micrographics and optical memories for document and image recording,
13、 storage and use. Annexes A and B of this International Standard are for information only. IV BSI BS*IS0*7565 93 m 3624669 0393948 954 m INTERNATIONAL STANDARD IS0 7505:1993(E) Micrographics - Readers for transparent microforms - Measurement of characteristics 1 Scope This International Standard spe
14、cifies methods and in- struments for measuring the characteristics for readers specified in IS0 6198. It applies to magni- fication, resolution, distortion, screen luminance, screen contrast and film gate temperatures. 2 Normative references The following standards contain provisions which, through
15、reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applyi
16、ng the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 5-1 : 1984, Photography - Density measurements - Part 1: Terms, symbols and notations. IS0 5-2:1991, Photography - Density measurements - Part 2
17、: Geometric conditions for transmission density. IS0 5-3: 1984, Photography - Density measurements - Part 3: Spectral conditions. I SO 5-4: 1983, Photography - Density measurements - Part 4: Geometric conditions for reflection density. IS0 446:1991, Micrographics - IS0 character and IS0 test chart N
18、o. 1 - Description and use. IS0 3334: 1 989, Micrographics - IS0 resolution test chart No. 2 - Description and use. IS0 61 96-1 :1980, Micrographics - Vocabulary - Section 01: General terms. IS0 6196-2:1982, Micrographics - Vocabulary - Section O.?: Image positions and methods of recording. IS0 61 9
19、6-3:1983, Micrographics - Vocabulary - Part 03: Film processing. IS0 61 96-4:1987, Micrographics - Vocabulary - Part 04: Materials and packaging. IS0 61 96-5:1987, Micrographics - Vocabulary - Part 05: Quality of images, legibility, inspection. IS0 61 96-6:1992, Micrographics - Vocabulary - Part 06:
20、 Equipment. IS0 61 96-7: 1992, Micrographics - Vocabulary - Part 7: Computer micrographics. IS0 61 98:-”, Micrographics - Readers for trans- parent microforms - Performance characteristics. CIE Publication No. 17.4:1987, International lighting vocabulary. 3 Definitions For the purposes of this Inter
21、national Standard, the definitions given in IS0 6196 apply. 4 Magnification 4.1 Apparatus 4.1.1 Magnification test target, consisting of a transparent stable material upon which is marked a graduated scale with an overall accuracy of f 0,5 % and which, when projected on the screen, will cover at lea
22、st 80 % of the reader screen width or height of 1) To be published. 1 BSI BS*ISO*75b5 93 lb24bb9 0393947 890 = IS0 7565:1993(E) the measurement area as shown in figure 1. The dis- tance between graduations shall be not greater than 0,2 mm. The magnification test target may be in- cluded with other t
23、est objects within the image frame. 4.1.2 Graduated reference scale, of at least scope may be used on front-projection readers. 200 mm in length, graduated in millimetres, having an overall accuracy of f 0,5 %, for measuring the image of the test target on the screen. 4.1.3 Magnifier, if necessary,
24、having a magnification between x 3 and x 12, for comparing the image length on the screen with the divisions on the gradu- ated reference scale. A hand-held magnifier may be used on rear-projection readers and a mounted tele- NOTE - Measurement area of the screen is defined as the central area forme
25、d by connecting the points of the diagonals that are located from the corners at a distance of 1 O % of the screen diagonal lengths and is shown as the area within the dashed rectangle. If the corners of the screen are rounded, the length of the diagonal and the points from which readings are taken
26、are calculated from the intersection of the extrapolated edges of the screen. The screen may be square or a vertical or hori- zontal rectangle. Figure 1 - Measurement area of reader screen 2 BSI BS*IS0*7565 93 = I1624669 0393950 502 4.2 Procedure Insert the magnification test target in the reader fi
27、lm gate with the scale in the horizontal position so that when at best focus, the image appears at the centre of the reader screen. The best focus is the setting of the focusing control that is judged to produce the best overall level of screen image resolution within the measurement area. This sett
28、ing is found exper- imentally and will usually be somewhere between the setting which produces the highest resolution at the centre of the screen and the settings which produce the highest resolution at the corner. Using the graduated scale, measure the length of the projected image using the magnif
29、ier if required. The magnification, M, is calculated as follows: length of image length of object M= Repeat with magnification test target inserted in the film gate so that it appears in the vertical position on the reader screen. Take measurements at other locations and orien- tations in the measur
30、ement area of the screen to de- termine the uniformity of magnification. This also aids in evaluating screen image defects such as key- stoning, pincushion and barrel distortions. 5 Resolution 5.1 Test charts Use either IS0 No. 1 or IS0 No. 2 microtest chart to determine resolution. 5.1.1 IS0 No. 1
31、microtest chart This is a microimage of the IS0 No. 1 test chart. The values given in IS0 6198:-, table 1, are the minimum values of the characters to be read at the appropriate reader magnif cation. 5.1.2 IS0 No.2 test chart As there is, at present, no standard specifying the IS0 No.2 microtest cha
32、rt, use a microimage of an IS0 No. 2 test chart at a known reduction to evaluate the pattern resolved on the screen at the known magnification of the reader being evaluated. Then use the ratio to determine the true value of the pattern resolved before comparing it with values in IS0 6198:-, table 2.
33、 Until certified microimage test targets are available, the test image used shall be ca- pable of resolving at least four patterns higher than those specified in IS0 6198:-, table 2, for the ap- propriate magnification. IS0 7565:1993(E) 5.2 Magnifier Use a magnifier to determine the character or pat
34、tern resolved on the screen (see 4.1.3). 5.3 Procedure Measure the resolution in accordance with IS0 446 (No. 1 test chart) or IS0 3334 (No. 2 test chart). Once best focus (see 4.2) has been achieved, do not alter it during the reading. Operate at the rated voltage as specified in 7.1.2. 6 Geometric
35、 distortion 6.1 Test film The test film carries a grid pattern with 0,25 mm squares made by lines with a thickness of 0,025 mm or less (see figure 2). The grid pattern shall be at least equal in size to the gate of the reader being tested. The thickness of the film shall not be greater than 0,18 mm.
36、 The test film shall be presented in a form that can be loaded in the reader and projected on the screen in the same manner as the microforms for which the reader is designed, .e. in sheet form for readers for microfiche or image cards and in roll form for readers for roll film. If the test film is
37、in roll form, the grid pattern shall extend across the full width of the film with its horizontal lines parallel to the edge of the film. 6.2 Procedure Load and position the test film in the reader so that the lines of the grid pattern, as imaged on the screen, run horizontally and vertically across
38、 the screen. If the reader is fitted with an image rotating prism, rotate the prism to give an image that is upright and right- reading on the screen. Then set the reader lens at best focus. Locate the image of the rectangle so that its corners are as close as possible to the four screen corner posi
39、tions, A, B, C and D of the measurement area (see figures 1 and 2). For readers with flat screens, either rear- or front- projection, attach a sheet of dimensionally stable, translucent (can be opaque with front-projection readers) material (e.g. polyester drafting film), which is slightly larger th
40、an the rectangle piojected on the screen, to the front of the screen in such a way that it is held taut and in contact with the surface of the screen. Then trace the four corners of the rectangle A, B, C and D on the material. Then trace the mid- points of the four sides of the rectangle similarly.
41、Remove the tracing material from the screen and, using a straightedge and a fine-pointed pencil (or similar device), draw straight lines between the four corner points to form a rectangle. 3 BSI BS*ISO*75b5 93 m Lb24669 0391951 449 m IS0 7565:1993(E) 6.2.1 Curvilinear distortion (barrel, pincushion)
42、 6.2.2 Geometric distortion (keystone) Measure the displacement of each of the marks rep- resenting the mid-points of the four sides of the rec- tangle, as imaged on the screen, from the mid-point of the adjacent straight line drawn on the tracing ma- terial. Express the displacement as a percentage
43、 of the length of the straight line. The greatest of the four values is taken as the measure of curvilinear distortion (see figure 3). Measure the lengths of the four sides of the rectangle drawn on the tracing material. If opposite sides of the rectangle differ in length, keystone distortion is pre
44、s- ent. Express the distortion as a percentage for both pairs of sides by dividing the difference in length be- tween the two sides by the mean length and multi- plying by 1 O0 (see figure 3). Image of test film grid II1 11 /I II -t- I -+i C+-l-+- . -1- .A II Il II I I IlIIIII -1- - -4-4- - -! -1- I
45、I -ti- - I -I- ll ll II II Il II II II II II II II -ri- I -II IlIIIII I IlIIIII I I I II Il II I I Di/ I I I Rectangle for distortion measurement 10 % corner positions Edge of screen f 0.5”, *) All four corners shall conform to this tolerance. Figure 2 - Illustration of image distortion test pattern
46、 4 BSI BS*IS0*75b5 93 m Lb24bb 0393952 385 9 I I I I I l I I Barret PIZ_- - - - - - - - - - I I Pincushion Curvilinear distortion Skew Geometric distortion Keystone NOTE - Dashed line represents ideal image area. Figure 3 - Distortion patterns 6.2.3 Geometric distoflion (skew) Measure the lengths of
47、 the two diagonals of the rec- tangle drawn on the tracing material. If these differ in length, skew is present. #Express the distortion as a percentage by dividing the difference between the two lengths by the mean length and multiplying by 1 O0 (see figure 3). NOTE 1 In the case of readers with cu
48、rved screens, it may not be possible to get the sheet of tracing material to lie against the surface of the screen without wrinkling. In this case, four separate 10 mm wide strips of tracing ma- terial are placed, one at a time, in contact with the screen so that the side of the rectangle being meas
49、ured lies ap- proximately along the centre of the strip. The two end points and the centre point of the side are then traced in the manner described. Each strip is identified with the appro- priate screen position, viz. tiop, left, right and bottom. For skew measurement, additional strips can be placed across IS0 7565: 1993 (E) the diagonals of the rectangle and the two end points marked in each case. 7 Screen luminance 7.1 General conditions Measure the screen luminance from a single eyepoint, located nominally perpendicular to the cen- tre of the screen. It is n
