1、Reference number ISO 11698-2:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 11698-2 First edition 2000-08-01 Micrographics Methods of measuring image quality produced by aperture card scanners Part 2: Quality criteria and control Micrographie Mthodes de mesurage de la qualit de limage produite par les
2、numriseurs de cartes fentre Partie 2: Critres et contrle de qualitISO 11698-2:2000(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licens
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5、 it is found, please inform the Central Secretariat at the address given below. ISO 2000 All rights reserved. Unless otherwise specified, 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
6、mission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserve
7、dISO 11698-2:2000(E) ISO 2000 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees.
8、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 organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Internat
9、ional Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies
10、for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of ISO 11698 may be the subject of patent rights. ISO shall not be held responsible for identifyin
11、g any or all such patent rights. International Standard ISO 11698-2 was prepared by Technical Committee ISO/TC 171, Document imaging applications, Subcommittee SC 1, Quality. ISO 11698 consists of the following parts, under the general title Micrographics Methods of measuring image quality produced
12、by aperture card scanners: Part 1: Characteristics of the test images Part 2: Quality criteria and control Annexes A and B of this part of ISO 11698 are for information only.ISO 11698-2:2000(E) iv ISO 2000 All rights reserved Introduction Scanning of microimages in aperture cards for use in CAD and
13、electronic information systems is of great importance. This International Standard provides means of evaluating the output quality of images resulting from scanning of aperture card microimages. The procedures may be used to establish and maintain image quality achieved by a scanner. The specificati
14、on of the test microimages can be found in ISO 11698-1.INTERNATIONAL STANDARD ISO 11698-2:2000(E) ISO 2000 All rights reserved 1 Micrographics Methods of measuring image quality produced by aperture card scanners Part 2: Quality criteria and control 1 Scope This part of ISO 11698 specifies methods f
15、or using the test images specified in ISO 11698-1 to check the quality of images produced by aperture card scanners. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 11698. For dated reference
16、s, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 11698 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references,
17、the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 3272-1:1983, Microfilming of technical drawings and other drawing office documents Part 1: Operating procedures. ISO 5457:1999, Technical produc
18、t documentation Sizes and layout of drawing sheets. ISO 6196-1:1993, Micrographics Vocabulary Part 1: General terms. ISO 6196-4:1998, Micrographics Vocabulary Part 4: Materials and packaging. ISO 6196-5:1987, Micrographics Vocabulary Part 5: Quality of images, legibility, inspection. ISO 6196-6:1992
19、, Micrographics Vocabulary Part 6: Equipment. ISO 6428:1982, Technical drawings Requirements for microcopying. ISO 12651:1999, Electronic imaging Vocabulary. 3 Terms and definitions For the purposes of this part of ISO 11698, the terms and definitions in ISO 6196 and ISO 12651 apply. Where a term ap
20、pears in both of these standards it is essential that the definition used is appropriate to the context of the term. The following terms and definitions also apply.ISO 11698-2:2000(E) 2 ISO 2000 All rights reserved 3.1 barrel distortion distortion in an image in which a specific point within the ima
21、ge is relatively farther from its optical axis than the corresponding point on the original, typified by a rectangle having one of its sides bowed outward 3.2 image offsets adjustment device of a scanner that allows the capture size area to be moved relative to the nominal position that is specified
22、 in the relative International Standard for the aperture of an aperture card 3.3 pincushion distortion distortion in an image in which a specific point within the image is relatively closer to its optical axis than the corresponding point on the original, typified by a rectangle having one of its si
23、des bowed inward 3.4 resolving power numerical expression of the limit of resolution of an imaging system, expressed as the number of lines per millimetre discernible in an image of a test chart 3.5 scaling error relationship between the nominal and actual numbers of pixels or dots per length in an
24、output electronic image 3.6 scanner offsets adjustments of the scanner system that calibrate the position of the capture area to be centralized over the standard card aperture area when image offsets are set to zero 3.7 test card aperture card or piece of photographic film having the same dimensions
25、, containing a test image in the aperture or equivalent area 3.8 test image area of a test card that contains test targets, patterns, etc., intended for measuring quality of image produced by an aperture scanner 3.9 test target target comprising elements such as test charts, patterns and characters,
26、 used for assessing the quality of output from an imaging system 4 Methods of use 4.1 General Because of its impact on the accuracy of other tests, evaluation of focus shall be made first. Other tests may be made in any order, taking account of interdependence of results as indicated in the method.
27、Test images shall be scanned into an electronic imaging system. Output images, on screen or as hard copy, shall be examined to assess quality level of characteristics. For a given bit-mapped image this may be different from its ultimate image on screen or as hard copy. Some characteristics shall be
28、assessed by visual inspection, others by measurement. For measurement of screen images, a calibrated electronic viewing system by which any pixel in view can be displayed as an X direction and Y direction pixel count from a reference corner of an image shall be used. The linesISO 11698-2:2000(E) ISO
29、 2000 All rights reserved 3 in the image shall be aligned within 2 with the corresponding axis of the measuring device of the viewing system. Errors in alignment greater than two degrees are likely to affect the accuracy of scaling and capture size tests. For measurement of hard copy images, appropr
30、iate allowance shall be made for error introduced by the printer and it is essential that the magnitude of any printer error be determined by separate calibration of the printer. Either or both methods may be used for evaluation but an electronic viewing measurement system is usually capable of prod
31、ucing more accurate results. No criteria for characteristics are specified. These are for the user to decide. 4.2 Establishing a quality reference To establish the quality reference the system shall be working at optimum level for all types of material to be scanned. Each of the test images specifie
32、d in ISO 11698-1 1) and any other test image made by the user shall be scanned, regenerated as hard copy print of corresponding A size and evaluated. If the quality of the printed output is acceptable the prints shall be retained for reference and the reference bit-mapped images securely retained on
33、 a separate disk. All scanner adjustment settings and all other system settings used to make the reference prints shall be recorded. 5 Test methods 5.1 Focus 5.1.1 Set the scanner for the highest resolution and reduction ratio, and allows the full test image area to be scanned. 5.1.2 Scan a type 4 t
34、est image and display the resulting image on a monitor screen or print it. 5.1.3 Examine the test targets and record the letter of smallest pattern that can be resolved in each set of patterns in all the test targets. 5.1.4 Check that the lines ruled in the background area are clearly separate over
35、the complete image area. NOTE Adjusting the focus of a scanner may require a special tool and procedures that are only available to service technicians. However, it is important to ensure that the quality of focus is maintained and this test image enables focus to be checked and measured. 5.2 Image
36、centring 5.2.1 Set the scanner offsets correctly. 5.2.2 Set the image offsets to zero. 5.2.3 Load a type 1 test image into the scanner. 5.2.4 Scan the test image and display the resulting image on a monitor screen or print to fit a sheet of paper of size in the ISO A series. Note cut-off readings on
37、 the metric scales of one horizontally and one vertically connected pair. Calculate the deviation from centre in each direction by subtracting the smaller reading from the larger one and dividing the result by two. For a paper print it will be necessary to correct the result for any deviation from n
38、ominal size of the sheet and any error in positioning introduced by the printer. 1) Test images are available from Applied Image Group/Imaging, 1653 East Main Street, Rochester, New York 14609 USA. Tel: (716) 482-0300. Fax: (716) 288-5989. Website address: E-mail address: ISO 11698-2:2000(E) 4 ISO
39、2000 All rights reserved 5.3 Image scaling 5.3.1 Set the scanner to scan the sheet size indicated on the type 1 test image to be scanned. 5.3.2 Set the pixel length and pixel width to the values obtained by multiplying the relative dimension of the sheet as specified in ISO 5457 by the scanning freq
40、uency in pixels per millimetre. 5.3.3 Set the reduction ratio to that specified in ISO 3272-1 for the sheet size being used. 5.3.4 Scan the test card and display the resulting image on a monitor screen or print to the sheet size indicated on the test image, using a printer having printing resolution
41、 equivalent to that of the scanner. 5.3.5 On the screen image, using a calibrated electronic viewing system, determine the number of pixels along the lines HF and EG between the centre pixels in the perpendicular lines defining the ends of HF and EG. Divide the numbers obtained by the scanning resol
42、ution used in the test to give length of the lines in millimetres. 5.3.6 On the printed image measure the lengths of lines HF and EG to the nearest millimetre. Correct for any error due to inaccuracy in enlargement ratio of the printer. 5.4 Image capture size 5.4.1 Set the scanner to scan the sheet
43、size indicated on the type 1 test image to be scanned. 5.4.2 Ensure that the scaling is correct as in 5.3. 5.4.3 Check that the pixel length and pixel width set for the sheet size correspond to the standard ISO sheet size multiplied by the resolution to be used in the test. 5.4.4 Check that the redu
44、ction ratio set for the sheet size being used is equal to the nominal reduction ratio specified in ISO 3272-1 for the sheet size being used. 5.4.5 Scan the test image and display the resulting image on a monitor screen or print it. 5.4.6 Observe the display or the print. Absence of broken lines, wit
45、h readings of 2,0 mm on each of the corner scales indicate correct image capture/scan size if there is no centring or scaling error. Whether or not broken lines are present, unequal readings on each corner scale indicate centring error. Equal readings on all the corner scales having a value other th
46、an 2,0 mm indicate scaling error. In interpreting the results of this test due allowance must be made for any error in centring or scaling revealed by tests in accordance with 5.2 and 5.3. 5.5 Line straightness 5.5.1 Set the scanner to scan the sheet size indicated on the type 1 test image to be sca
47、nned. 5.5.2 Scan the test card and display the resulting image on a monitor screen or print it. 5.5.3 On the screen image, using a calibrated electronic viewing system in combination with a vector overlay facility, select each of the lines in the rectangular grid in turn and join each end by an over
48、laid vector line. Enlarge the display in regions of maximum deviation between the raster line and the vector line and measure the maximum deviation between the two lines, in pixels, in a direction normal to the line. Express the maximum deviation in millimetres, obtained by dividing the number of pi
49、xels counted by the resolution used in pixels per millimetre. 5.5.4 On the print select each of the lines in the rectangular grid in turn and using a straight edge carefully draw a fine line between the ends of the line. Measure the maximum deviation using a graticule under magnification.ISO 11698-2:2000(E) ISO 2000 All rights reserved 5 5.6 Orthogonality Before deviation from orthogonality, caused by misalignment of the scanning device, can be measu
