Testing of the best printing suitability test vers

2022-07-23
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Testing of Printability test edition (Part 1)

in order to provide reference samples for publishing houses and reference data for printing and paper enterprises, the Publishing Association selected five kinds of light-weight paper for physical index testing and on-line printing testing to evaluate their printability and visual effect under the same printing conditions. In order to investigate and evaluate the printability effect of the paper, the edition Association entrusted us to design and produce the printability test version

in order to objectively and truly reflect the printing applicability of the tested paper, when designing the printing applicability test plate, the focus is on the visual effect of the printed sample. In terms of the selection of test items, we mainly selected the test items for the reproduction effect of natural images, including visual evaluation items such as typical character skin color, tea color, dark green color, high profile, middle tone, dark tone, subtle level, clarity, geometric figure, gradient tone, non color structure, etc

in addition to evaluating the visual effect, we also selected some printing process control indicators related to printing suitability, such as reflection density, dot increase value, overprint rate, chromaticity value, printing relative contrast value (k value), dot reproduction, paper penetration density, etc. These indexes can be measured by special testing instruments, and the printability of the tested paper can be described and evaluated by physical quantities, eliminating the errors caused by human factors, which is more scientific

in addition, from the perspective of evaluating the quality of printing products, we have designed test and evaluation items such as registration, geometric deformation, appearance, text, flatness, gradient synthesis and resolution, so as to evaluate the printing suitability of the tested paper more comprehensively, objectively and truly

when designing the printability test version, we selected 8 standard natural images and 10 composite images provided in the iso12640 (GB/T) standard. In order to test the flat printing effect, we also selected the commonly used 70% deep and 30% shallow superimposed flat color blocks (mainly two-color superimposition) to meet the testing requirements for the printing suitability of light paper

considering the characteristics of light-weight paper, three sets of Printability test plates were produced with different dot line numbers of 120 LPI, 150 LPI and 175 LPI. The three sets of Printability test plates all adopt circular dots, and the dot angles also adopt the traditional y 90., M 45。, C 75。, BK 15。。 Because each color image in the printability test version adopts the electronic document provided by is012640 (GB/T) standard, there will not be much deviation in image plate making. The black-and-white image in the printability test plate is made by converting the color image data into gray image data. In order to maintain the restorability of the data, we have not adjusted the image tone and level, but still use the image data after the color image data is converted into gray level to maintain a relatively stable restoration effect

due to the size of the folio, In the process of plate making, we adjusted (mainly reduced) the size of the original standard image of "the value of this concept mainly lies in the iso12640 (GB/T1 to save costs for enterprises 872l-2002) The software can process the original data of experimental force, displacement, time, deformation and the curve combination derived from it. The 8 color natural images selected for the printability test version have their own characteristics and are used to make a special evaluation on the visual effect of the tested paper after printing (see the legend of the test sample for specific functions)

the five resolution composite images (icons) selected by the printability test plate are used to evaluate the reproduction of the resolution, registration accuracy and other conditions of the tested paper when other test conditions are relatively fixed, as well as the effects of molar fringes (moire) and virtualization. The graphics of the five selected resolution composite images (icons) are 1/4 of the dawn pattern, and the interval of each radiation angle is 4., Figure size is 30 mm × 30 mm, the values of the four color separations are the same. The radiation of resolution diagram 1 changes according to the sinusoidal law. It can evaluate the printability and visual effect of the tested paper, such as the smoothness of the image, the gray balance and the reproduction effect of the middle tone, through the change of the image radiation density (the figure completes a cycle every 4)

resolution diagram 2 is the binary representation of Fig. 1. In the radiation line, all point values of 50% or less shall be recorded as o%. All point values above 50% shall be recorded as 100%. Figure 3 is opposite to figure 2, that is, all point values of 50% or less are recorded as 100%, and all point values above 50% are recorded as o%. Figure 4 and figure 5 are generated in a similar way to figure 2 and figure 3. The difference is that the transformed point values are 80% and 40%, instead of 100% and o%. The purpose of selecting resolution diagram is the same as that of selecting resolution diagram 1, which is to evaluate the printability and visual effect changes of the image resolution of the tested paper under different conditions

the gradient color bar composite image selected for the printability test version is composed of 8 gradient images with continuous transition, and the gradient range is 100% to 0%. The 8 color plates are C, m, y, K, R, G, B and Bk. Among them, the last four are two-color and three color combined color strips of C, m and Y primary colors. These color strip images are used to evaluate the printing gradient effect of the tested paper. A total of 4 chromatographic synthetic images were selected for the printability test version. Chromatographic synthetic image 1 has 6 rows of color blocks, with 13 color blocks in each row; Chromatographic synthetic image 2 has 8 rows of color blocks, with 13 color blocks in each row; The chromatographic synthetic image 3 includes 12 blocks, each of which has 36 color blocks; The chromatographic synthetic image 4 includes 14 blocks, of which 25 are color blocks for each of the 10 blocks, and 16 are color blocks for each of the other 4 blocks. The chromatographic color reflected by these synthetic chromatographic images can meet the requirements of evaluating the printability and visual effect of the tested paper

in order to complete the physical index detection requirements for the printing of the tested paper, we selected the 1st, 2nd and 3rd color blocks (C 100%, m 100%, y 100%) in the 1st row of the chromatographic synthetic image 1 and the 12th color block (BK 100%) in the 2nd row as the reference color blocks for measuring the printing density and color degree of the sample. Match the above four color blocks with the third color block (80% of C, m, y and BK respectively) in rows 3, 4, 5 and 6 of image 1 to measure the printing relative contrast value (k value) of each tested paper; The two-color overprint rate of each tested paper is measured by matching with three color blocks in Row 2: 5 (C 100%, BK 100%), 6 (m 100%, BK 100%), 7 (Y 100%, BK 100%). In addition, we selected the second (80% of each color), the fifth (50% of each color), and the eighth (25% of each color) color block in row 3, 4, 5, and 6 to measure the dot gain rate of each tested paper, and also selected the 11th (100% of each color) color block in Row 2 to measure the back transparent density of each tested paper. (see the attached figure for the specific description of the four chromatographic synthetic images)

in order to reflect the flat printing effect of a large area, the printing suitability test plate intentionally lays common flat on the explanatory text of the natural image. Figures 1, 2, 3 and 4 show about 30% of the light colors, and figures 5, 6, 7 and 8 show about 70% of the deep colors (mainly two-color and three color superimposed multicolor), which are used to evaluate the color reproduction effect of the tested paper after printing. Due to the influence of space, the printability test edition failed to arrange test items for the layout using words and multiple fonts and font sizes, which is hereby explained

based on the principle of scientific rigor, neutrality and impartiality, we have carefully tested the printing test samples of five kinds of light paper provided by the association. The test items mainly involve the printability indicators of the printing samples, including: visual effect, the printing effect of each natural image reflecting its characteristics, tone reproduction, uniformity, point reduction, color density, overprint, transparence, etc. a total of 5L items have been tested. After nearly a month of intensive testing, all testing indicators and results have been completed. According to the testing results, No. 2 and No. 4 of the five tested papers are more suitable for low-grade color printing, and No. 3, No. 1 and No. 5 are more suitable for monochrome printing (monochrome printing based on text). See the attachment (testing records) for the measured conditions

I. description of test items

since the purpose of the test is to test the printability of various light paper, we focus on the content to be tested in the test items, namely: the reproduction visual effect of tone tone, the uniformity of printing, point reduction and reproducibility, the penetration degree of the back, dryness, overprint of printed matter, geometric dimension change, field printing effect, etc. In addition, the printing conditions such as powder and wool dropping, printing paper running and wrinkling are not within the detection range. Due to the lack of detection methods, some indicators (such as the gloss of printed matter) can not be evaluated with quantitative values

II. Testing instruments and testing environment

in order to make each testing parameter truly reflect the actual situation of the tested object, we will send all the testing instruments and equipment used to the Metrology Institute for verification and calibration. The instruments used for this test are:

(1) sx40 times reading microscope with light source (Wenzhou, Zhejiang)

(2) aseli X-Rite 418 color reflection densitometer (United States)

(3) TCS color analyzer (Beijing aoyike) test environment: temperature 20 ℃, relative humidity 45%, natural light of light source (equivalent to 5500 K), which meets the requirements of visual evaluation standards

(to be continued)

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