GB/T 20439 This part specifies the test method for evaluating the consistency of the output quality of black and white reflective scans of office documents during their use by using a test target. This part is applicable to the evaluation of the output quality of black and white scanners. GB/T 20493.2-2006 Test targets for black and white scanning of electronic imaging office documents Part 2: Method of use GB/T20493.2-2006 Standard download decompression password: www.bzxz.net
GB/T 20439 This part specifies the test method for evaluating the consistency of the output quality of black and white reflective scans of office documents during their use by using a test target. This part is applicable to the evaluation of the output quality of black and white scanners.

ICS37.080
National Standard of the People's Republic of China
GB/T20493.2--2006/IS012653-2.2000 Electronic imaging
Test target for the black-and-white scanning of office documents-Part 2:Method of use(ISO 12653-2:2000,IDT)
Published on August 23, 2006
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
Digital anti-counterfeiting
Implemented on February 1, 2007
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GB/T20493.2—2006/IS012653-2:2000GB/T20493 "Test Standard for Black and White Scanning of Electronic Imaging Office Documents" is divided into two parts: Part 1: Characteristics; Part 2: Method of Use. This part is the second part of GB/T20493, which is equivalent to ISO12653-2:2000 "Test Standard for Black and White Scanning of Electronic Imaging Office Documents Part 2: Method of Use" (English version). This part corrects the editorial errors in ISO12653-2:2000 as follows: - Adjusted the diagrams in the "Description of Elements" column of Test No. 11 and Test No. 12 in the original text that are inconsistent with the standard; Corrected "Readability 3" in the "Japanese Standard" column of Test No. 7 in the original text to "Resolution 1". This part is proposed and coordinated by the National Technical Committee for Standardization of Document Imaging Technology (SAC/TC86). This part was drafted by the First Subcommittee of the National Technical Committee for Standardization of Document Imaging Technology. The main drafters of this part are Liang Ting, Dong Jianwei and Li Ming. This part is published for the first time.
GB/T20493.2—2006/IS012653-2:2000
This part of GB/T20493 provides a method for evaluating the output quality of black and white scanning systems for office documents using the test targets specified in GB/T20493.1.
There are test charts and test targets for microfilming and faxing, but these test charts and test targets are unique to these two fields and are not suitable for the needs of document scanning system users. 1 Scope
Electronic imaging
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GB/T20493.2—2006/ISO12653-2:2000 Test targets for black-and-white scanning of office documents
Part 2: Method of use
This part of GB/T20493 specifies the test method for evaluating the consistency of the output quality of black-and-white reflective scans of office documents during their use using the targets specified in GB/T20493.1--2006 and other targets. This part is applicable to the evaluation of the output quality of black-and-white or color office documents (whether or not they have halftones or color) scanned by black-and-white scanners.
This part does not apply to color scanners or scanners for scanning transparent or semi-transparent documents. 2 Normative references
The clauses in the following documents become the clauses of this part through reference in this part of GB/T 20493. For all referenced documents with dates, all subsequent amendments (excluding errata) or revisions are not applicable to this part. However, parties to agreements based on this part are encouraged to study whether the latest versions of these documents can be used. For all undated referenced documents, the latest versions are applicable to this part.
GB/T6161-1994
(eqvISO3334:1989)
Micrographics Test Chart No. 2 Characteristics and Its Application in Micrographics GB/T18405--2001 Micrographics ISO Character and Test Chart No. 1 Characteristics and Its Use (idtISO446:1991) GB/T20225-2006 Electronic Imaging Vocabulary (ISO12651:1999, MOD) ITUT.22 Recommendation Standardized Test Charts for Document Fax 3 Terms and Definitions
The following terms and definitions established in GB/T20225-2006 and apply to this part. 3.1
Test element
The pattern represented on the test target.
Examples: Metric ruler, gray scale, circle. 3.2
continuoustone
The variation in tone represented by areas of different densities in a document. 4 Methods
4.1 Overview
The methods for evaluating the output quality of black and white scanners can be used in the following situations: - Initial setting of the system to produce satisfactory images; - Checking the consistency of quality;
- Checking whether the same performance is obtained from other systems. If the entire system is checked from input to output, the results obtained will vary depending on the equipment used. For example, the screen of a monitor that has not been adjusted will have a lower quality display than one that has been adjusted. Therefore, it is important to adjust the parts of the system to be tested in advance. If other parts of the system must be tested, then the tests should be repeated as appropriate. Regular and standardized use of the above procedures should be able to provide a certain level of quality assurance. This method is used to:
- enable the operator to check whether the scanner has been debugged; to enable the operator to understand the functions and application scope of the scanner; to enable the user to monitor the quality of the image over a certain period of time; to enable the user to develop a quality evaluation procedure. 4.2 Quality
Factors that affect the quality of the document scanning system are: irregularities in the physical scan;
inconsistent exposure;
color sensitivity of the photometric device
- contrast,
- setting of the reading value;
halftone reproduction;
resolution;
- ratio.
5 Procedure
5.1 System Initialization
The test should be carried out under normal operating conditions. Before the test begins, warm-up should be carried out. If conditions are suitable, initial adjustment should also be carried out according to the manufacturer's instructions.
5.2 Use of Image Enhancement and Compression Techniques
The output quality of the scanning system may change due to the use of image enhancement and compression techniques. For these tests, the system should be set up to work under normal conditions so that normal documents are depicted. It is advantageous to set up the system to the best conditions during initial testing. After a change in software, which may use different enhancement or compression techniques, a new initial test setup may be required. 5.3 Scanning Test Targets
When scanning test targets, the target should be correctly positioned in the scanner. If quality problems are obvious due to incorrect movement of the scanner relative to the target, the scanned image should be discarded. For example, if the target is obviously misaligned due to paper path problems, the target should be rescanned.
Scan the test target (see Figure 1) and view or print the image. Note: Figure 1 is for information only. It has been reduced and is not suitable for use as a test target. 5.4 Internal Test Systems
Many systems include test programs in their software. These tests may be performed in conjunction with the test targets specified in this part of ISO 12653.
5.5 Frequency
The frequency of testing the system should be determined by the user based on the recommendations of the system supplier. It is best to test the system before scanning a batch of documents and, if necessary, again at the end of the batch. Testing should also be performed after the system has been maintained or parts have been replaced.
6 Evaluation of test results
7.2 describes the tests to be performed on each test element of the test target. 2
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GB/T 20493.2—2006/ISO12653-2:2000 The results obtained should be checked on the screen or on hard copy. Normally, readability on the screen will be poorer than on paper output. However, both methods should be used so that defects specific to each output device can be shown. For quality control purposes, a reference data file of quality control images should be kept. 7 Methods
7.1 Test elements
Table 1 gives a list of test elements. 7.2 gives the details of the various tests for these elements on the test target. Figure 2 indicates the target area for each test element of the test target (see Table 1). Table 1 List and description of test elements
Test number
Characteristics measured
Frame 2
Diagonal scanning
Circular scanning
Readability 1
Readability 2
Resolution 1
Resolution 2
Resolution 3
Evenness
Continuous tone reproduction
Halftone reproduction
Isolated small symbols
7.2 Test procedure
Target area
Determine the integrity of the scan.
a) Measure the displacement of the image;
b) Measure the output ratio.
Determine the accuracy of the diagonal reproduction.
Determine the accuracy of reproduction of the ring.
Purpose of Test
Determine the minimum size at which the test character No. 1SO1 can be clearly reproduced. Determine the minimum size at which characters of different printed fonts can be clearly reproduced. Determine the resolution of the system.
Determine the directional effects of resolution.
Determine the limits of the ability to reproduce details.
Determine the uniformity of reproduction of solid areas.
Determine the accuracy of the reproduction of the continuous tone density spectrum. Determine the limits of the ability to reproduce halftones within a certain range of screen sizes. Determine the ability to reproduce small non-alphanumeric characters. Tests No. 1 to 13 should be performed using the original test plate and not copies thereof. The tests described should be performed on the screen and/or on output hard copy as required. GB/T20493.2—2006/ISO12653-2:2000AGBR
WNOPORSTUVWXYZabcdafghijkkm
nopqrsluvwxyz.7s0123456789
Y355750123456789
889888
CEFEEEE
Test standard plate structure example
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judee tlipm
Stop-age inspection
Chaozu short effect
Important internal device
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GB/T20493.2—2006/ISO12653-2:2000 Figure 2 Layout of the test area of ​​the standard board
CB/T20493.2—2006/ISO12653-2:2000 Objective
Frame 1
Purpose of the test
Description of the elements
Frame 2
Purpose of the test
Description of the elements
Determine the integrity of the scan.
Test 1
Target Area A
Diamond frame with one sharp corner touching the edge of the test target.
Check that all diamonds are visible and as complete as the scanner allows. None.
Indicates that the target is correctly positioned in the scanner
This test is only meaningful if the entire image can be displayed. Test 2
Measures the displacement of the image;
b) Measures the output ratio.
a) 1. None.
2. Vertical position: IA-B!, IF-E
Horizontal position: IC-DI.IH GI.
Target Area A
Grid frame with millimeter scale at the edge of the target. Millimeter scale of the extension line.
1. Note the cutting of the four sides of the grid line at the corner. 2. Measure the length of line segments A, B, C, D, E, F, G, H.
Measure the length of each of the four sides.
b) Ratio - side length of image/side length of test target. Frame 2
Diagonal Scan
Purpose of Test
Description of Elements
Test No. 2 (Continued)
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CB/T20493.2-2006/IS012653-2:2000 Target Area A
If there is an even cut on any side, there is a lateral displacement towards that side. If there is an uneven cut along the sides, there is a rotation.
Vertical, if IC-D|=|HG|=0 → Centered. IC-DI-HG|≠0→|tt||[CD||HG]
Horizontal, if IA-B|-|FE|=0
IA-B|=|FE|0
IA-B|≠|FE
Judge whether the position and reproduction ratio are qualified, not centered.
→Not centered and (or) rotated.
Centered.
Measurement on a curved screen surface is difficult. Test No. 3
Determine the reproduction accuracy of the diagonal:
Not centered.
Not centered and (or) rotated.
Region B
Diagonal with two marks equidistant from the center of the target, the length of the diagonal between the two reference marks: L.
Measure the length (L) between the two reference marks on the diagonal output.
Measure the maximum offset between the output diagonal and the theoretical line between the two reference marks.
a) Length inaccuracy (%) = —×100
Linearity inaccuracy (%) =
a) LeLIH GI.
Region A
Grid frame with millimeter scale at the edge of the target. Millimeter scale of the extension line.
1. Note the cuts of the four sides of the grid line at the corners. 2. Measure the lengths of the lines A, B, C, D, E, F, G, H.
Measure the length of each of the four sides.
b) Ratio - side length of image / side length of test target. Frame 2
Diagonal Scan
Purpose of the Test
Description of the Elements
Test No. 2 (Continued)
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CB/T20493.2-2006/IS012653-2:2000Region A
If any side is cut uniformly, there is lateral displacement towards that side. If there are uneven cuts along the sides, there is rotation.
Vertical, if IC-D|=|HG|=0 → Centered. IC-DI-HG|≠0→
[CD||HG]
Horizontal, if IA-B|-|FE|=0
IA-B|=|FE|0
IA-B|≠|FE
Judge whether the position and reproduction ratio are qualified, not centered.
→ Not centered and (or) rotated.
Centered.
Measurement on a curved screen surface is difficult. Test No. 3
Determine the reproduction accuracy of the diagonal:
Not centered.
Not centered and (or) rotated.
Region B of the target plate
Has a diagonal line with two marks equidistant from the center of the target plate, and the length of the diagonal line between the two reference marks is: L.
Measure the length (L) between the two reference marks on the output diagonal line. www.bzxz.net
Measure the maximum offset between the output diagonal line and the theoretical connecting line between the two reference marks.
a) Length inaccuracy (%) = —×100
Linearity inaccuracy (%) =
a) LeLIH GI.
Region A
Grid frame with millimeter scale at the edge of the target. Millimeter scale of the extension line.
1. Note the cuts of the four sides of the grid line at the corners. 2. Measure the lengths of the lines A, B, C, D, E, F, G, H.
Measure the length of each of the four sides.
b) Ratio - side length of image / side length of test target. Frame 2
Diagonal Scan
Purpose of the Test
Description of the Elements
Test No. 2 (Continued)
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CB/T20493.2-2006/IS012653-2:2000Region A
If any side is cut uniformly, there is lateral displacement towards that side. If there are uneven cuts along the sides, there is rotation.
Vertical, if IC-D|=|HG|=0 → Centered. IC-DI-HG|≠0→
[CD||HG]
Horizontal, if IA-B|-|FE|=0
IA-B|=|FE|0
IA-B|≠|FE
Judge whether the position and reproduction ratio are qualified, not centered.
→ Not centered and (or) rotated.
Centered.
Measurement on a curved screen surface is difficult. Test No. 3
Determine the reproduction accuracy of the diagonal:
Not centered.
Not centered and (or) rotated.
Region B of the target plate
Has a diagonal line with two marks equidistant from the center of the target plate, and the length of the diagonal line between the two reference marks is: L.
Measure the length (L) between the two reference marks on the output diagonal line.
Measure the maximum offset between the output diagonal line and the theoretical connecting line between the two reference marks.
a) Length inaccuracy (%) = —×100
Linearity inaccuracy (%) =
a) LeL0. The image is reduced.
b) If e≠0: The image is distorted.
The validity of this test is affected by the difference in input and output resolution. This test can also be used to detect aliasing conditions. GB/T20493.2-2006/ISO12653-2:2000Objective
Circular ring scanning
Purpose of the test
Description of elements
Readability1
Purpose of the test
Description of elements
Determine the accuracy of the reproduction of the circular ring.
Test No. 4
Region C of the standard
Concentric circles with the center coinciding with the center of the standard and with horizontal and vertical diameter lines equidistantly distributed on the surface
Vertical diameter = D,
Horizontal diameter = D
Measure the vertical and horizontal diameters of each circle with a ruler. Geometric distortion -
Geometric distortion greater than 1 can indicate:
The scanning speed of the scanner and/or printer is uneven;
The resolution of the output device is not high enough.
The accuracy of the result will be affected by the difference between the horizontal scanning speed and the vertical scanning speed. Most screens have a geometric distortion of less than 1.
Test No. 5
Determine the minimum size of the ISO No. 1 test character that can be clearly reproduced. A part of the ISO No. 1 test chart (see GB/T18405-2001).
Determine the smallest resolvable character according to the method of GB/T18405-2001.
Region D
The number of the smallest resolvable character multiplied by 10 gives the height of the resolvable character in microns. The number of the smallest resolvable character of the ISO No. 1 test chart indicates the minimum height of the reproducible character. Due to the better contrast of the test characters and the high reproduction accuracy, the readability of the output can be better than that of ordinary document output.
Readability 2
Purpose of the test
Description of the elements
Resolution 1
Purpose of the test
Description of the elements
Test No. 6
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GB/T20493.2--2006/IS012653-2.2000 Standard Plate E Area
Determine the minimum size at which characters of different fonts can be clearly reproduced. r2sqd
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Identify and count the number of readable characters.
Determine the minimum readable character size.
Give the height of the reproducible characters.
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Specify the character fonts that are compatible with the system resolution. Characters of different fonts and sizes.
Due to the better contrast, the readability of the test character output can be better than the readability of the original output. Test No. 7
Determine the resolution of the system.
Region F of the standard
Part of the test chart No. 2
(see GB/T6161-1994).
Determine the smallest resolvable pattern according to the method of GB/T6161-1994. None.
The marking number of the smallest resolvable pattern of the test chart indicates the system resolution in line pairs per millimeter. None.
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