The hottest p2qm prepress and printing quality man

2022-10-04
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P2qm - Prepress and printing quality management

introduction

p2qm (prepress & press quality management) is a high-quality color management scheme developed by screen company for digital workflow to comply with the trend of smaller printing volume, lower cost and on-demand printing in the printing market. The center of the scheme is the production of color proofing and digital ideal proofs, while monitoring the changes in color management in modern workflow

I. proofing of traditional workflow

in the color management process of traditional film based workflow, color proofing can adopt chemical proofing or traditional offset proofing. In order to make the printed matter consistent with the proof, ink color adjustment is required on the printing machine. In this process, it is worth emphasizing the following three points:

1 It is a high-cost production method to specially produce chips for chemical proofing

2. Using the traditional round flattening offset proofing machine to proofing can indeed accurately simulate the effect of printed products, and even often exceed the quality of printed products

3. Color adjustment on the printing machine is a relatively flexible means of color control

however, if we look at the above points 2 and 3 from another perspective, we can find that although offset proofing can simulate the effect of printed products, it is inseparable from the feelings and skills of proofing operators. In addition, the intermediate link of film output is time-consuming and material consuming

second, CTP workers input data storage by experimenters, and single-chip computers use programs to control the liquid crystal display and keyboard on the operation panel. The digital proofing of the workflow

CTP workflow eliminates the intermediate link of outputting film, and widely uses DDCP (color digital direct proofing) to replace the chemical proofing. However, CTP workflow also has some problems

1. True halftone plus output is often not supported, and the paper used for proofing is usually different from the paper used for printing. In this way, the matching between proofs and printed products is always limited

2. Color proofs that can accurately match the printed products need to be made in a digital way

in the process of realizing point 2 above, the direction of the latest technological development is to use ICC preset documents to control the differences between equipment and various printing conditions, and build a system that can simulate the finished printing products. The "labfit color management system" of the screen is precisely located here at the Jung industrial seminar

as we all know, CTP workflow can maximize the use of PDF format data. In this way, the data processed by Rip can be used as the basic data for calculating the ink coverage, and then the ink bucket key is preset, which greatly improves the automation of preparation before starting up. However, although the adjustment process of ink bucket key is automated, it may not ensure that the printed product can accurately match the proofing draft. In this case, the operator is still required to have a high enough level to further fine adjust the ink volume during the printing process

III. printing machine proofing of CTP workflow

when the DDCP system cannot completely solve the proofing problem, it is necessary to use the printing machine for proofing. In fact, this plan is feasible. This is due to CTP technology, which speeds up production. Of course, this is also inseparable from the improvement of the printing machine speed

generally, the sample printed by the printing machine should be very close to the printed product. However, there are still some obstacles that make the color difference between the proofing draft and the printed product, such as the uneven level of the operator and other subjective factors in the setting stage of the printer. In this way, the printer operator still needs to make some fine adjustments in the printing process in order to achieve the matching between the printed product and the proof. Obviously, this will lead to a reduction in productivity. In this case, although only a few proofs are needed, a lot of master paper needs to be used. In other words, all this has reduced productivity and increased production costs

towards full digital workflow

after discussing the problems existing in the current color management scheme, let's take a look at how to really ensure the printing quality in the printing process. "Ensure printing quality" - this sentence is very simple to say, but it is not easy to do, because it means that many adjustable variables on each printing machine need to be accurately and digitally controlled. Moreover, it is also a common phenomenon that a printing company uses printing machines of various brands. Therefore, any color management scheme must be able to adapt to these complex environments. Although CTF and CTP workflow avoid some dangerous situations existing in the traditional analog production mode, color proofing has become a difficult problem to solve. One of the biggest problems faced by current color proofing systems is that some of the colors they produce are colors that printing ink can't show at all. How can we talk about digital control of these colors? As a result, it still depends on the technical level and feeling of the operator

on the road to full digital workflow, the two main factors we need to comprehensively consider are: how to achieve the most effective color management; What is the best proofing method

on the road to full digital workflow, the problems we need to solve are:

1 After realizing the automatic setting of ink bucket key based on CIP3, 2. The scope of application of peeling force testing machine: applicable to the stretching, peeling, deformation, tearing, heat sealing, bonding, puncture force of plastic film, composite material, soft packaging material, plastic hose, adhesive, adhesive tape, self-adhesive, medical patch, protective film, release paper, combination cover, metal foil, diaphragm, backplane material, non-woven fabric, rubber, paper fiber and other products What is the best way to ensure the printing quality in the printing process

2. How to realize the color management between different brand printing machines

3. What is the best way to use ICC to preset documents

in addition, as more and more printing companies begin to use digital printing machines, the integrated and effective color management of digital printing machines has also become an urgent problem to be solved

p2qm status:

p2qm is a comprehensive color management solution developed by the screen and provided for the whole workflow from prepress process to printing process, which conforms to the international standards of ICC and CIP3 printing industry

it is feasible to carry out unified color management for printing machines of different brands, because the whole system of printing production will be compatible with the widely accepted ICC and CIP3 standards. The main benefit of this is that the whole system will become more flexible and can fully enjoy all the benefits brought by digitalization

at present, the two main tools used to improve the scientific accuracy of printing are screen TrueFit and DCC system

truefit is an online density measurement system, which has been installed on the truepress series digital offset press. DCC is used to provide the analysis data of printing samples required for the automatic control of ink fountain keys. In addition, labfit module can be used to establish high-quality ICC preset documents, so as to master the characteristics of each printer and ensure the same quality under a variety of different output conditions. P2qm elements TrueFit, DCC and labfit work together to realize the p2qm workflow

the difference between the feedback cycle in the color control process of digital offset press and traditional offset press lies in those independent TrueFit and DCC devices. However, since these two types of equipment basically control the ink density, the purpose of these two types of cycles is actually the same. The purpose of labfit is to function in the data stream fed back to rip, by improving the non rip processed data used in color proofing and printing processes and providing them with better rip processed data, so as to achieve closer to the ideal sample of digital version

therefore, there are two feedback cycles in the p2qm workflow. Among them, the function of a cycle is to better calibrate the printing machine, so that different printing machines can achieve the same printing quality; Another cycle is to ensure that the proofing system is consistent with the output quality of the printer

truefit:

truefit is an online density measurement system, which can keep the truepress series digital offset press of the screen at a consistent high quality level

truefit is installed in the paper receiving area of truepress digital offset press and is composed of the newly designed measuring head and light source components. When the paper enters the receiving area, TrueFit can measure the signal bar on the printing sample in real time, so as to control the ink density more accurately during the printing process

dcc (digital color console):

DCC is equipped with a "full page one shot" digital camera carefully designed by the screen to faithfully measure color images. It can read the color data on printing samples, color proofs, and even standard samples, and then analyze these data to calculate CIP3 data and ink bucket key data. There are three advantages to doing so

1) according to CIP3 and color proofing data, ink bucket key data can be calculated for ideal printing samples

2) even if the signal bar is not used, the ink density data can be read directly from the graphic part on the printing sample

3) with the labfit color management system of screen company, lab data can be calculated by reading the 85 color signal bar of screen company. In addition, labfit can easily generate ICC preset documents based on printed samples and proofs

labfit and 85 color signal bar:

the 85 color signal bar used by labfit is a new technological achievement developed by screen company. It can generate ICC preset documents by printing narrow four-color signal strips with only 85 color blocks (usually, to generate ICC preset documents, you need to use a full format color signal sample containing 800 ~ 1200 color blocks)

the reduction of the number of color blocks required for color measurement not only makes the color management process simpler and faster, but also enables us to easily arrange the color signal bar on the layout in the routine production process. In this way, lab data can be obtained from the printed samples on a regular basis

p2qm and standard production printing machines:

another function of p2qm is to improve the color consistency of offset printing machines. It achieves this goal through the following three ways, each of which involves the ICC of the screen:

1) in labfit, an ICC preset document is established for each major variable (printer, paper, ink, etc.) that affects the printing quality and the DDCP system, so that color matching can be achieved from the perspective of these variables

2) obtain CIP3 data from the samples approved by customers, compare these data with the ideal samples of the digital version, and feed back the comparison results to the ink supply system

3) the color proofing draft can be taken to DCC for measurement and comparison with the test sample taken out in the actual printing process, and the comparison results can be fed back to the ink supply system

color management of the currently used production printing press - output characteristics

lab number can be established by reading the sample printed with labfit85 color signal strip in DCC

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