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1、BRITISH STANDARD BS 7353:1991 Methods of Measuring quality of output of graphic COM recorders Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 This British Standard, having been prepared under the d
2、irection of the Information and Documentation Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 28 February 1991 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference DOT/16 Draft for comment 89/9555
3、9 DC ISBN 0 580 18869 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Information and Documentation Standards Policy Committee (DOT/-) to Technical Committee DOT/16, upon which the following bodies were represented: British Coal Corpor
4、ation British Computer Society British Office Technology Manufacturers Alliance British Photographic Association Drawing Office Material Manufacturers and Dealers Association EEA (the Electronics and Business Equipment Association) Her Majestys Stationery Office London Borough of Bromley Ministry of
5、 Defence National Association of Microfilm Bureaux National Centre for Information Media and Technology (Cimtech) Society of British Aerospace Companies Standing Conference of National and University Libraries United Kingdom Association for Information and Image Management The following bodies were
6、also represented in the drafting of the standard, through subcommittees and panels: Ordnance Survey Public Record Office Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolle
7、d Copy, (c) BSI BS 7353:1991 BSI 09-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definition1 3Evaluation of graphic COM images1 4Test methods1 Appendix A Line density8 Appendix B Method for assessing the effect of character display and rotation8 Figure 1 Test fram
8、e for frame size, linearity and positioning4 Figure 2 Test frame for resolution, legibility and density5 Figure 3 Test frame for radial recording6 Figure 4 Test frame for curved lines7 Figure 5 Test frame for measuring character display and rotation9 Publications referred toInside back cover License
9、d Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 ii BSI 09-1999 Foreword This British Standard has been prepared under the direction of the Information and Documentation Standards Policy Committee. Increas
10、ing numbers of technical drawings are now produced on computer output microfilm (COM), and, although their quality is usually reasonable, they are not always compatible with microfilm copies of hard-copy drawings. This can cause difficulty when both kinds of drawing are put into aperture cards and s
11、ent through systems designed to deal with microfilm copies of hard-copy drawings. This British Standard has therefore been prepared to help users to establish procedures that should ensure that the quality of COM-generated drawings is both acceptable in itself and compatible with technical drawings
12、on conventional microfilm that comply with BS 4210-1, BS 4210-2 and BS 4210-3. The test frames specified may be used for rough checks if users wish to monitor the quality of COM-generated drawings without going to the expense of carrying out the tests described in this standard. Figures are provided
13、 by the Association of Information and Image Management, ref. MS39-1987. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer i
14、mmunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in
15、 the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 BSI 09-19991 1 Scope This British Standard describes methods for measuring the image quality of COM-g
16、enerated drawings. It is not concerned with the kind of film used, but assumes that a film is used that is capable of producing images of the required quality. Appendix A gives guidance on the line density of first-generation film. Appendix B gives a rough check for character display and rotation. N
17、OTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definition For the purposes of this British Standard the following definition applies. resolution ability of a photographic system (equipment, optics, sensitized material and processing) to record f
18、ine detail 3 Evaluation of graphic COM images 3.1 General The evaluation of the quality of a graphic COM image is a complex task. Various conditions can occur in a graphic COM recorder that are not found in source-document systems or alphanumeric COM recorders, which can be evaluated with the use of
19、 a form slide. Many graphic COM recorders have no provision for a form slide and, if they are to be evaluated, all measurements need to be taken from the microform image produced by the dynamic image generator. NOTE 1It is customary for graphic COM recorders to produce negative-appearing film images
20、. For clarity of presentation, the examples in Figure 1 to Figure 5 have been reproduced as positive-appearing images. NOTE 2For general information about technical drawings on microfilm, see BS 4210-1, BS 4210-2 and BS 4210-3, and for the processing and storage of archival film, see BS 1153. 3.2 Ap
21、paratus 3.2.1 Travelling microscope, with a magnification within the range 50 to 150. 3.2.2 Densitometer 4 Test methods 4.1 Test runs The test frames described in 4.2.2, 4.3.2, 4.4.2 and 4.5.2 shall be run on the COM recorder as part of the acceptance testing and the film made shall be retained as a
22、 reference copy for comparison test runs. Before the tests are run, the operator shall ensure that the film processor is in proper working order. The images generated during a test shall be examined and, if any shows signs of deterioration in quality, the entire set of images shall be re-run and exa
23、mined. Runs of test frames shall be kept for long enough to show whether problems are intermittent or increasing. 4.2 Test for frame size, linearity and positioning 4.2.1 Principle A travelling microscope is used to take various measurements of the image of the test frame to check whether they compl
24、y with the manufacturers specification. 4.2.2 Test frame The test frame (see Figure 1) contains a rectangular grid equal in size to the largest image. The frame is divided by lines drawn in both axes at intervals of one-eighth of the length of the long axis, from the centre of the frame. Diagonal li
25、nes connect the opposite corners of the frame and the midpoints of the sides of the frame. 4.2.3 Procedure 4.2.3.1 General The frame is recorded at the beginning and end of each test run (see 4.1). NOTEThe specified limits referred to in all the methods of test are those specified by the manufacture
26、r. 4.2.3.2 Frame size To determine the frame size, measure the length of the centrelines EG and HF. 4.2.3.3 Line straightness Align the film so that the endpoints of the centreline HF coincide with the X axis of the microscope. Traverse the line and measure the maximum deviation of the centre of the
27、 line from the X axis along the Y axis. Repeat the test for the outside lines AB and CD. Align the film so that the endpoints of the centreline EG coincide with the Y axis of the microscope. Traverse the line and measure the maximum deviation of the centre of the line from the Y axis along the X axi
28、s. Repeat the test for the outside lines AD and BC. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 2 BSI 09-1999 State whether the maximum deviation is within the specified limits. To find the per
29、centage of deviation, divide the maximum deviation by the line length and multiply that number by 100. 4.2.3.4 Rectangularity and orthogonality First check that the straightness of the centrelines is within the specified limits and then measure the diagonal lines, EF, EH, FG, GH, AO, BO, CO and DO,
30、to check that they are of equal length. 4.2.3.5 Linearity Measure the distance of each grid line intersection from the X axis and the Y axis and compute the location of the “best fit” grid to check that the distance of each actual line intersection from the corresponding line intersection of the “be
31、st fit” grid is within the specified limits. 4.2.3.6 Line width To check that a line is of uniform width, traverse the line and measure its minimum thickness and its maximum thickness. 4.2.3.7 Alignment of image centreline to film edge To check that the horizontal centreline of the rectangle is para
32、llel to the reference edge of the film, align the X axis of the microscope with the reference edge of the film. Measure the distance from the reference edge of the film to the horizontal centreline of the frame at the centre of the line and at the endpoints. 4.2.3.8 Image centring To check that the
33、horizontal centreline of the image is positioned at a distance of one-half the nominal film width from the reference edge of the film, measure the distance from the reference edge of the film to the horizontal centreline. For aperture cards, in addition make similar measurements for the vertical cen
34、treline. 4.3 Test for resolution, legibility and density 4.3.1 Principle The resolution that can be obtained in a graphic COM recorder depends on the number of addressed points at which a spot may be displayed, the spot size, the quality and focus of the lens used to image the spot on the film, the
35、exposure level, the film type and film processing. When the resolution capabilities of a system are described, it is essential that all requirements necessary to achieve the resolution are specified. Legibility is measured on the image of the test frame to ensure that the final legibility complies w
36、ith specified requirements. Background visual diffuse reflection density is measured to check that the film-processing system is operating consistently. For line density see Appendix A. 4.3.2 Test frame The test frame (see Figure 2) contains: a) patterns composed of five-line groups that serve the s
37、ame purpose as the line groups of the ISO resolution test chart no. 2 (see BS 4657), with a letter beside each group to identify it; b) groups of lower-case letter “e” in various sizes, with a numeral beside each group to identify it; c) an area produced by overwriting in such a way as to expose the
38、 film totally for the purpose of measuring the films minimum achievable density (Dmin). 4.3.3 Procedure 4.3.3.1 General The frame is recorded at the beginning and end of each test run (see 4.1). 4.3.3.2 Resolution Using a travelling microscope with a magnification of 0.5 to 1.0 of the resolving powe
39、r expected, examine the targets at the centre and in each corner of the frame. Note the letter of the smallest resolvable group of lines in each target, following the method described in BS 4657. NOTEGroups are designated by letter rather than numerical value because the resolution recorded is a fun
40、ction of image size. The actual resolution in line pairs per millimetre may be determined by consulting a table supplied by the manufacturer of the COM recorder. 4.3.3.3 Legibility Using the unaided eye, examine the groups of letters “e” and note the group number of the smallest letter that is fully
41、 legible. 4.3.3.4 Density Using a densitometer, measure the background visual diffuse reflection density of the area described in item c) of 4.3.2 and note the Dmin. value. NOTEThe Dmin. value should be not greater than 0.2, lower if possible, if the best results are to be achieved. 4.4 Test for rad
42、ial recording 4.4.1 Principle A travelling microscope is used to take measurements on the image of the radial recording test figure to determine whether the system records radial vectors equally well in all directions. 4.4.2 Test frame The test frame (see Figure 3) contains parallel pairs of radial
43、vectors spaced at 22.5, with the separation in each pair of vectors being equal to the line thickness. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 BSI 09-19993 4.4.3 Procedure 4.4.3.1 General R
44、ecord the frame at the beginning and end of each test run (see 4.1). 4.4.3.2 Vectors Take measurements to check whether all vectors are of equal density and are continuous and straight, without signs of misaligned butting, and whether the lines meet in the centre and are parallel in each vector pair
45、. 4.5 Test for curved lines 4.5.1 Principle Measurements are taken on the image of the test frame to check the systems accuracy in producing curved lines. 4.5.2 Test frame The test frame (see Figure 4) contains a number of concentric circles, with 45 diagonal lines. 4.5.3 Procedure 4.5.3.1 General R
46、ecord the frame at the beginning and end of each test run (see 4.1). 4.5.3.2 Measurement Using a travelling microscope, measure the four radial lines of each circle to check that the distance from the circumference of a circle to the centre is the same along any radius. Licensed Copy: London South B
47、ank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 4 BSI 09-1999 NOTEThe letters at the corners, midpoints and centre of the frame have been added for ease of reference in the text. They need not appear on the film. Figure 1 Test
48、 frame for frame size, linearity and positioning (see 4.2) Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 BSI 09-19995 Figure 2 Test frame for resolution, legibility and density (see 4.3) Licensed
49、 Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 6 BSI 09-1999 Figure 3 Test frame for radial recording (see 4.4) Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7353:1991 BSI 09-19997 Figure 4 Test frame for curved lines (see 4.5) Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:44:08 GMT+00:00 2006, Uncontrolled Co
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