Graphic technology--Prepress digital data exchange--CMYK STANDARD colour image data(CMYK/SCID)
Some standard content:
GB/T187212002
This standard is equivalent to ISO12640:1997 "Printing Technology-Prepress Data Exchange-CMYK Standard Color Image Data (CMYK/SCID))
The purpose of formulating this standard is to provide a set of color image data that is independent of input devices for the vast prepress industry in my country, so as to provide a testable and comparable section for electronic publishing systems and their output and post-processing. In addition to all the standard texts, this standard also comes with a CD containing the color image data of this standard, and the file format is TIFF format. Appendix A and Appendix B of this standard are the appendices of the standard. Appendix A is a reminder appendix. This standard was proposed by the Press and Publication Administration, and this standard is under the jurisdiction of the Jinguo Printing Standardization Technical Committee. The author of this standard is the China Institute of Printing Science and Technology. The drafters of this standard are Li Jiaxiang and Ma Zhiyong.
GB/T 18721—2002
ISO (International Organization for Standardization) is the world federation of international standardization bodies (ISO member bodies). The formulation of international standards is usually completed through ISO technical committees. A corresponding technical committee is established for each topic, and each member body interested in a topic has the right to become a representative of the technical committee. All official or non-official international organizations that cooperate with ISO can also participate in this work: in the field of electrotechnical standardization, ISO works closely with the International Electrotechnical Commission (IEC). The draft international standards proposed by the technical committee are subject to voting by member countries. The formal publication of an international standard requires the approval of at least 75 member countries concerned.
International Standard IS12640 was drafted by ISO/TC130 (Printing Technical Committee). Annexes A and B are components of this international standard, and Annex C is only a reference material. GB/T 18721-2002
ISO Introduction
The technical content of this standard is coordinated by the Image Processing Technical Standards Committee of Japan, with the support and cooperation of the second working group of the International Organization for Standardization of Printing Technology Committee.
Requirements of standard digital test images
The following figure shows a block diagram of the typical functions involved in the image processing process in print reproduction. There is no system that can simultaneously provide encoding and communication functions and read/write operations by those devices installed in the same location, but when considering the requirements and development of these test images, the expert group has considered a system that can include all functions such as image processing, data storage, encoding and data transmission. The typical system process is usually to scan a test image at point A and check the image's properties or changes in these properties at each level of the system. However, due to differences between scans, it is almost impossible to repeatedly generate the same data file with the original reference image, so it is impossible to compare performance characteristics between different systems or different locations. Image original
Print proof
Image recorder
Image processing
Image processing
Decoder
Decoder
High quality image reproduction and transmission system
Network
To solve this problem, a set of test images that can be provided in digital form and are independent of the equipment used is required, so that the image data can be compared before and after processing at each stage of image processing (except input and scanning), or the effects of different processing methods can be evaluated at the final output.
The following are typical examples of the use of these test images. Objective comparison of color output systems such as printing, color proofing, color fax (facsirlile). These comparisons include image processing time, system performance, image quality, color reproduction (inelity), etc. - Evaluation of the effectiveness and efficiency of coding methods, data compression, and data transmission. - Quality characteristics of printed output products of traditional processes and direct digital output devices. It is believed that these images will be used in many industrial fields besides the printing industry, where quality will be affected by data transmission, image processing, storage and recording. Characteristics of test images
The performance of any color reproduction system will be visually (observing the final output image) and objectively evaluated by measuring the control components. This requires that the test images should include natural scenes (pictures) and control signal bars. Because the subjective evaluation of the image results will be strongly affected by the image content, it is very important to ensure that these natural scenes are of high quality and include a variety of subjects. 14
GB/T 18721—2002
Development of digital test images
We have conducted an extensive survey of all T130 member countries to determine the desired image content and to solicit suggestions for images that can be considered.
This set of images includes 1 natural image and 1 synthetic image. The natural images include skin tones, images with extremely subtle gradations of light or dark, neutral tones, brown wood grain that is difficult to reproduce, memory colors, complex geometric shapes, and gradations of highlights and shadows. The synthetic images include resolution detection charts, uniform gradients of negative and auxiliary colors, and CMYK data representation areas defined in the ISO 12612 standard for describing four-color printing.
Using a common electronic printer in the printing industry, the color natural images are converted into MYK data. The scanning parameters of each image are optimized to meet common reproduction requirements. Five resolution detection icons and five color test charts are generated by electronic methods. In order to meet the wide requirements of the printing industry, two sets of resolution/data encoding combinations are selected for all images. Both have pixel alternating data, which uses the upper left corner of the image as the data starting point (dataarigin>. The first set of data is G pixels/mra (about t pixels/in), and the code number 28~228 represents the printing gradation value of 0%-100%: The second set of data is 12 pixels/mi (about 300 pixels/in), and the code number 0--255 represents the printing gradation value of 0%~100: These data are stored on the CI>ROM CD according to the file format requirements of the 1SO966D standard: The file format is the TIFF/IT format determined by TSO12639. This file format is also consistent with the TIFF in Section 16 of the 6th revision The format is compatible. If necessary, the file can be processed and imported by a custom image processing software on a general platform widely used in the industry. It should be emphasized that the gray balance of these images is independent, but not the most accurate in any particular printing case. Users are required to use these images as a tool to determine the reproduction characteristics under different T conditions, but there is a "correct" or "ideal" reproduction.
National Standard of the People's Republic of China
Printing technology prepress data conversion
CMYK standard color image data (CMYKSCIDGraphic technology-Prepress digitel data exehange-CMYK standard colour image data (CMYK/SCID)1 Range
GB/T 18721---2002
idtISo 12640:1997
This standard specifies a set of data representing color images that can be used to evaluate image quality or changes during encoding, image processing (including transmission compression and decompression), and output or printing for research, development, product evaluation and process control. 2 Referenced standards
The following standards contain provisions that constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T16969-1997 Information technology Read-only 120nm data compact disk (CD-ROM) data exchange (idt ISO/IEC 10149:1995)
GR/T16970-1997 Information technology Read-only compact disk storage (CD-ROM) volume and file structure for information exchange (idt ISO 9660:1988)
IS0 12639:1998
Printing technology—Prepress data exchange—Image file format for off-image processing. IS0 12642:1996
Printing technology
IS0 14672:2000
Printing technology
3 Definitions
This standard adopts the following definitions.
3.1 Checksum
Prepress data exchange - input data used for four-color printing feature description Prepress data exchange -
SCILD image statistics
Used to check whether the file has been correctly transmitted. The sum of the data in the file: Note 1: Usually only the least significant bit is checked. 3.2 Colour sequence
The order of colours printed on the substrate or stored in the data file. 3.3 Colour value
The colour value associated with each pixel.
3.4 Data range datarange
The range of data values.
3.5 dot percentage dotpercentage
Relative area percentage of the halftone dot, ranging from 0% to 100% Note 2: The closer the minimum dot is to the image, the closer the dot is to 0%: the larger the dot is in the image area, the closer the coverage is to 100%.
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Approved on 2002-05-21 Implemented on 2003-01-01
GB/T 18721 2002
3.6 global colour change globalcolourchange The local colour change relative to a selected area of an image. The relative colour of all parts of the image is changed. 3.7 colour scanner input colour scanner A device that converts the reflected or transmitted light of a photograph (or other original) into electronic signals that are set into a regular relationship in a specific area of the image being evaluated. 3.8 Image orientation
Specifies the starting point and direction of the first line of data from the perspective of the end user observing the image content. The orientation code used is specified in ISO12639.
3. 9 Pixel
In digital imaging systems, the small image element, 3.T0 pixel interleaving pixel interleaving The data of the cyan, magenta, yellow and black color values of a pixel are adopted by the next pixel in the same color value sequence. 3. Other color data interleaving forms are linear and planar. 4. Technical conditions
This standard contains data recorded on a CD-ROM entitled \GB/T18721-2002 Printing technology prepress data exchange CMYK standard color image data (CMYK/SCID) - Appendix A - Standard color image data. Appendix A is an integral part of this standard. The image characteristics of these data are described in Chapter 5 and the electronic data structure is described in Chapter 6. ·5 Data Description
5.1 Data Resolution
This standard data has two different combinations of data encoding ranges and resolutions: basic data set: its encoding range is from 28 to 228, indicating that the dot percentage is from 0% to 100%, and the data interval is 16 pixels/mm (406 pixels/in) in the effective image size (128mm×160mm); alternative data set: its encoding range is from 0 to 255, indicating that the dot percentage is from 6% to 100%, and the data interval is 12 pixels/mm (305 pixels/in) in the same image size. The alternative data set is generated from the basic data set through analyzable transmission rules. Both sets of data contain the same image, the difference is that the alternative data set has a line of small characters \1SO300\ in the front wall of the image, while the basic data set is \1SO400": 5. 2 Data set definition
Both the basic and alternative groups of standard color image data include 8 natural (photographic) images and 10 computer-generated artificial images. The natural images in the basic group are represented by NI to NB, and the letter "A" (such as NIA) is added in the alternative group. Each image also has a name based on the content of the picture (such as: cafeteria). The artificially synthesized images include resolution maps and color maps, which are represented by SI to SI0 for the basic group and S1A to S1OA for the alternative group.
5.2.1 Natural images
The characteristics and typical applications of natural images are described in Table 1. The names of these images are in their labels. After the code is identified, the image is listed. Figure 1 shows a monochrome schematic diagram of these natural images. Information on other statistical characteristics of these images is described in ISO14672. These natural images have the following characteristics:
Image size:
Basic group: 2560 pixels (long side) × 2048 pixels (short side) Alternative group: 1920 pixels (long side) × 1536 pixels (short side) Note 4: This size is equivalent to the actual size of the image is 160mm × 128mm or 6.3in × 5.04in. The recommended resolution for reproduction is 16 pixels/mm (basic group) or 12 pixels/mm (alternative group). Alternation: Pixel alternation
GB/T 18721
Color sequence C (cyan), M (magenta) Y (yellow), K (black) Color value:
Basic group: 8-bit binary data is linearly proportional to the percentage of printed dots, 28 digital codes represent 0%, 228 Indicates 100%.
Substitution group: 8-bit binary data is linearly proportional to the percentage of printed dots, with a digital code of 0 representing 0% and 255 representing 100%. Image data orientation: Horizontal dithering starts from the upper left and ends at the lower right. Note 5: The data encoding of each file header is described in Appendix C, and its file format is consistent with the provisions of 1S012639. Table 1 Natural image
N2 Buffet restaurant
N3 Fruit basket
N Wine and tableware
Bicycle
N Musician
NS Wedding
52.2 Synthetic images on people
Special images of models used to evaluate the reproduction of human skin tones Images with complex geometric shapes, suitable for evaluating the effects of image processing Fruit baskets, cloth and wood
Image of an orchid with a gradient background, used to evaluate the effect of gradient tones in highlight areas and shadow areas
Image of three women, used to evaluate the effect of different skin tones and subtle image gradations
Dark-tone images of portraits of mothers with various items, used to evaluate the effect of dark tones, especially dark brown and dark green
Resolution icons
Composite images S1 to S5 and S1A to S5A are resolution icons, used to evaluate the resolution of the output device, the accuracy of the color separation film, and the effect of texture and blur. There are 5 different patterns, each of which is a quarter of a dawn or star pattern, with each rescue ray spaced 4", and each pattern is 400 pixels × 40 pixels (basic set) or 30) pixels × 300 pixels (alternative set). The corresponding size is 25 mm × 25 mm, and the values of all 4 color separations are the same. The values of
S and SIA vary according to the sine law, so the smoothness of density changes, the reproduction of gray balance, and the reproduction of midtones can be evaluated (tested). The S1 and 51A patterns complete a period every 4°. The relationship between the image tone value and the angle between the image and the X-axis (counterclockwise) 8 is:
Tone value (%) -50 + 50sin (90 × 0) The synthetic images S2 and S2A are S1 and S1A The binary representation of all values 50% or less is recorded as 0%, and all values above 60% are recorded as 100% (the reading is 50%). S3 and S3A are also similar binary images, with values below 50% recorded as 100% and values above 50% recorded as 0% (the opposite of S2 and S2A). S4 (S4A) and S5 (S5A) are produced in a similar way to S2 (S2A) and S (S3A), except that the dot values are 80% and 40% instead of 100% and 0%. Figures 2 and 3 show the results of the resolution of the labels. The substitution group of the resolution icon is distinguished from the basic group by the daily line in the upper right corner. The substitution group has a line, which is about 1.5 mm wide and forms a 45\ angle with the corresponding image.3 Artificial synthetic images - color atlas Artificial synthetic images S6 and StA have 8 lines, 2512 pixels × 3048 pixels and 1884 pixels × 2286 pixels respectively, each of which is a continuous transition new variable screen, 256 pixels × 3032 pixels and 192 pixels × 2274 pixels respectively. The range of the discontinuous variable screen is 0% to 100% dot area for the four color separation slices of the fan, as well as the combination of two-color and three-color in cyan, magenta and yellow. These characteristics are shown in Figures 4 and 5. In the blank area between K (black) and R (red), SG and S6A also have the meaning "I5O400\ and\ISO300. Artificial synthetic images S7 to S10 and S7A to S10A provide image elements defined in ISOO12642. The combination of these elements 153
GB/T 187212002
The combinations are selected and arranged so that they can be reproduced on 8.125in×11in or A4 size paper, with the color blocks having a side length of 6mm, or as a single color block with a side length of 1mm. The built-in graphics of 15012642 show such a layout. The small color block numbers and dot percentages should be consistent with those defined in JS012642: the layout of these color blocks is shown in Figures 6 to 11, and the combination of dot percentages of these color blocks is the same for the basic group and the alternative group. The positions of all color blocks in each set of free spectrum are alternating, with Use a colorimeter or densitometer to measure in the middle of the color block. All color blocks in the basic group are 160 pixels × 160 pixels each, and the spacing between color blocks is 1G pixels. The color blocks in the replacement group are 120 pixels × 120 pixels each, and the spacing between color blocks is 12 pixels. In addition, the edge width of each color block group is 8 pixels, and the width of the edge of the replacement group is 6 pixels. Therefore, the connection space between each color block group and the adjacent color blocks is 16 pixels (or 12 pixels). When each color block is output at the specified resolution, the actual size is 10mm × 10mm. The layout of each color block group is selected as follows;
S7 There are 6 rows of color blocks in S7A, 13 in each row, and 8 rows of color blocks in S8A, 13 in each row, which together represent all the basic data defined in 150 12642. They are 2 288 pixels × 1 056 pixels and 2.288 pixels × 1 408 pixels respectively. S7A and S8A are similar to S7A. Similar to S8, but with 1716 pixels: ×792 pixels and 1716 pixels ×1056 pixels respectively. $9 (S9A) includes 12 blocks, each with 36 color blocks: total pixel count is 3168 pixels ￥4224 pixels (2375 pixels ×3168 pixels for the alternative group), S10 (S10A) includes 14 blocks, 10 of which have 25 color blocks each and the other 4 blocks have 6 color blocks each, the overall size of the color spectrum is 246 pixels ×1400) pixels (1848 pixels ×3300 pixels for the alternative group), including empty areas without color block images.
6 Electronic Data
6. 1CD-ROM Data Content
The CD-ROM attached to this standard contains the data files of Appendix A and the 36 images listed. The file names are consistent with the image names listed in Clause 5.2. Table 2 lists the file names, file sizes, the descriptive name of each data file, and the pixel height and pixel width of each image. The file size indicates the size of the file recorded on the CD including the header file. The checksum given in Appendix B is used to check whether the data is complete.
5. 2CD-R (OM operating system compatibility
On the CE-ROM of SCILD (Standardized Color Image Data), the standards used for each format layer are as follows: =Physical format layer: GB/T1606 (ID1IS()/IEC10149) Capacity and file format layer: GB/16970 (ID1S09660) -Application software format layer: JS012639
TIFF/IT-CT format conformity level (confarmity level) is the basic group used for SCI1) images, and the TIFF/IT-CT/P1 conformity level is the alternative group used for SCI1 images. Appendix C shows the image header files of TIFF/IT CT and TIFF/IT CT/P1 formats: N1.TIF and NIA.TIF.
Note 6: Except for the wide dot data area, the other parts of the SCID image basic set are completely consistent with TIFF/IT-CT/P1. Note 7: The above file format is compatible with Section 16 of TIFF Revised Edition 6. If necessary, it can be input and processed by various common image processing software on various platforms.
Table 2 CD ROM data content
File name
N4,IIFF
File size
(bytes)
20972544
20972544Www.bzxZ.net
20072511
20972544
(pixels)
(picture)
Resolution
(pixels/mm)
Image name
Youzhu Restaurant
Diao and tableware
File name
S2, TIFF
S2A-TIFF
$3A. TIFF
S5A,TIFF
S10A.TIFF
File size
(bytes)
20 972 544
20 972 544
20972544
20 972 544||tt ||641 n24
6110241
641 024
641 n24
30627348
9665536
12887040
53 527 552
43367424
11 797 604
11 797 504
11 797 504
11 797 504
11 797 504
11797504
11 797 504
71 797 501
351024||tt| |361024
361 021
361 024
361021
17228320
437312
￥249408
30109696||tt ||2t 331 624
GB/T 18721—2002
Table complete)
(Pixel)
[Pixel]
Resolution
(Pixel/mm)||tt| |Image Name
Bicycle
Musician
Resolution Map
Resolution Map
Resolution Map
Resolution Map
Resolution Map
Teaching power diagram
Self-service salon
Wine and tableware
Bicycle
Musician
Resolution power diagram
Resolution power diagram
Resolution chart
: Resolution chart
Resolution chart
ISO400
N1 and N1A
N3 and N3A
N5 and N5A
N7 and N7A
GB/T 187212002
Figure 1 Reduced monochrome reproduction of natural images
N2 and N2A
N and NAA
NG and N6A
NS and NBA
222222222223
272222727
12227222
227727777
GB/T 18721—
C=M=Y=A
c=my=k
- =m=y
—40%
=R=y=k
=+50 (90×)(%)
238272272222
222272
Figure 2 Basic group resolution icon
=100 fold
c\m-ywk
c=my=k
2222222724||tt| |22272721277
GB/T18721—2002
00 pixels
=m=y=k
=100 %
c=mwyk
c=m=yk
Figure 3 Alternative group resolution chart
=m=yzk
=50+50( 00×)(%)
=m=y=h
272222
c=m=y=k
r=m=y=||tt| |c=may=k
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