Optimized Three-Stage Strategy of Orderly Management of File Stream in Network Printing Workflow

1 Introduction

In 2014, there are totally 105 thousand printing enterprises and 3.394 million employees in China. The gross product of printing industry has reached 1.08575 trillion RMB, and its overall size is close to the second largest one in the world. With the rapid development of computer and network communication technologies, customer demands for the production efficiency of Chinese printing enterprises are ever-increasing. Combining printing with e-commerce, the new intelligence system that connects to digital prepress workflow via network platform has become a research hot topic in the field of packaging and printing.

Till now, the world-renowned printing companies such as Kodak, Agfa and KBA have exhibited the original operating system of network printing[1]. Domestic and foreign scholars also have done a series of pioneering studies on network printing. However, those studies mainly focus on realizing the construction, typesetting and management of network printing flow. Article [2] introduces an optimized program which can help customers self-solve color issues occurring in the digital printing workflow via a web-based troubleshooting tool; Alexopoulos, et al.[3] developed a web-services oriented workflow management system for integrated digital production engineering; Balis[4] did a research on the workflow of hypermedia design paradigm based on web resources; Manso-Callejo, et al.[5, 6] proposed a method that makes use of automatically generated metadata in printing workflow; Article [7] introduced a digital texture printing workflow based on index; Murphy[8] studied on the optimization of cutting processing digital workflow based on XML format; Article [9] introduced the GA solution for scheduling problem of JDF workflow; Article [10] introduced the 5s management philosophy, it simplifies and improves post-press processing flow with the improved ECRS principle; Luo[11] adopted case-analysis research program to explore the implementation of information management and information analysis for the company T, and optimization for it. From the Articles above, it is obvious that many studies have been done on the construction of printing workflow, as well as color conversion, system, data stream, enterprise management mode involved in flow structure. Different from the papers mentioned above, this paper proposes the optimization for printing file stream, that is, the optimized three-stage strategy for customer preflight, prepress preflight and optimized sorting of prepress files in the network printing workflow.

2 Creation of Network Printing Workflow

Network printing is an epoch-making printing industry business model, which combines network’s capability of fast delivering information in the 21st century with the productive process of traditional printing industry. It has the feature that it is convenient to upload and deliver order files and achieve quick printing by connecting to prepress process. Original design files of network printing come from all over the country and have variant standards and styles. These original design files are discrepant with printable PDF files. Therefore, professional digital printing workflow systems cannot fully identify those formats. They should be converted by intermediate software. Even if the design draft is PDF file, it will also have numerous printing problems. Thus, to obtain printable PDF files, preflight is needed before printing and those formats that don’t meet the requirements should be modified. According to the requirements of customers and printing process, files preflight often involves hundreds of entries and requires a significant amount of time to modify file error and repeatedly confirm. To save the time of printing enterprise preflight and modification, shorten printing period, this paper presents the optimized three-stage strategy of orderly management, which includes customer preflight, prepress preflight and optimized sorting of files. Figure 1 shows a convenient automatic network prepress workflow created by applying Pitstop Pro, Connector You and Enfocus Switch. Customer preflight, Classification of received files and format conversion, files sorting and prepress preflight, makeup and output are involved in this workflow.

Figure 1

Schematic of Network printing workflow

3 Customer Preflight Strategy

Customer preflight means that it allows customers to participate in preflight and correction. As customers are more familiar with their own product requirements and product effects, those customer-related preflight errors are often returned to the customers for modification. Therefore, this paper presents the customer preflight strategy. Firstly, the process of classify preflight entries in terms of their possibility of error and correlation with customer, and then adopt Pitstop Pro to customize different customer preflight schemes. Finally, these schemes are loaded into the software named Connector You to produce different customer preflight applications. Customers can choose one application according to their own conditions, and they can complete self-preflight by loading design files into the application. If there are errors, the application will provide the error reports and customers can modify them based on the reports and then reload. Otherwise, files will be automatically delivered to printing enterprises.

Following steps discuss how to formulae customer preflight schemes. Firstly, a total number of 135 preflight entries are obtained through statistical analysis on the surveys we conducted. Secondly, the possibility of occurrence of errors for each of these 135 entries is investigated. In addition, by the means of distributing network questionnaires and visiting the printing enterprises, the measure of customer relevance is also investigated. In this investigation the possibilities of occurrence of errors are measure with scores ranging from 1 to 5 where a higher score indicates a higher possibility of occurrence of errors. Finally, the preflight entries are sorted according to the order of average scores from low to high. The sorted preflight entries list as shown in Table 1 where each entry has a number i (i=1, 2, · · ·, 135) and a name at the right side of the number. Then use a_i to denote the average score of entry numbered i and Figure 2 shows score a_i vs entry No. i as i goes from 1 to 135.

Figure 2

Average score based on occurrence of errors of preflight projects

By analyzing Figure 2, the scores of 135 preflight entries can be divided into 4 parts with interval of 1 point of score. The parts with higher scores cover fewer entries, which conforms to the fact that the preflight entries vulnerable to errors are concentrated and have a small number in the practical printing process. Thus the preflight entries are divided into four groups (each has a rank) according to the possibility of occurrence of errors. The first rank is No. 1 to No. 78, the second rank is No. 79 to No. 113, the third rank is No. 114 to No. 126 and the forth rank is No. 127 to No. 135. The higher rank, the possibility that errors occur in realistic preflight entry gets higher. While taking into account customer preflight relevance and the possibility of occurrence of errors, this paper presents four types of customer preflight schemes, they are quick-type, general-type, stable-type and comprehensive-type respectively, as shown in Table 1.

Using Pitstop Pro four types of preflight schemes can be built, and then each of them is loaded into Connect You to develop four customer preflight applications. Customers just need to transform the designed work into PDF and load it into the preflight applications mentioned above and it can preflight and be transmitted. Figure 3 is the screenshot that reflects the preflight situation, which adopts four different types of customer preflight schemes. The screenshot illustrates that errors increase with comprehensive preflight, and the more highly specialized error printing entries. Therefore, customers can select the corresponding preflight application according to their own situation. Quick-type preflight scheme can be adopted and modified when the printing files are simple and the customer is unfamiliar with the printing schemes; comprehensive-type preflight scheme can be adopted when the customer is very familiar with the printing schemes and customer requires high-quality files; general-type or stable-type preflight scheme can be adopted according to the situation when the requirement is neither too low nor too high. By this way, the rework of printed files can be reduced and designers’ efficiency can be improved.

Figure 3

Comparison of outcome of four types of preflight methods

4 Prepress Preflight Strategy

The prepress preflight is necessary for the received files in the network printing workflow, and different printing enterprises usually adopt variant preflight schemes. Unlike customer preflight, which considers customer-related error-prone entry, enterprises prepress preflight should take into account the professional entries, which are about printing technology and printing quality. Since errors of some entries in the preflight won’t affect the printing process and printing quality, they are tolerable in the actual printing. Once these entries are included into prepress preflight, it will result in much more errors, longer modification time and lower passing rate of workflow. Therefore, this paper proposes the concept of “prepress preflight tolerance” for the establishment of prepress preflight schemes. Some preflight entries cannot be neglected, such as hemorrhagic, font embedding, spot color, image resolution etc. Performing prepress preflight is necessary for these entries, and the preflight tolerance of them is set as zero, and the rest of tolerance is set as alert. After ascertaining the preflight tolerance according to the different requirements of printing technology and printing quality and establishing prepress preflight schemes on the basis of preflight tolerance, prepress preflight is completed via comprehensive-type preflight scheme and prepress preflight standard respectively, and results are shown in Figure 4. Eight samples of printing files are selected to into prepress workflow. When adopting comprehensive-type preflight scheme, five files pass the preflight, but the other three reveal errors, and the passing rate is 62.5%. However, the passing rate is 100% when adopting prepress preflight standard, which is based on preflight tolerance. Since errors checked out by the comprehensive-type preflight scheme in those three files are tolerant and passable for printing enterprises, prepress preflight scheme based on preflight tolerance is more accurate and can effectively shorten time.

Figure 4

Comparison of comprehensive preflight scheme and scheme based on prepress preflight tolerability

5 Optimized Sorting Strategy of Printing Files

After getting through the customer preflight, the prepress files orderly enter printing enterprises’ process of prepress preflight, printing and post-press. File-sort is often irregular in the printing enterprise, and staves usually empirically arranged printing order of files according to the total flow time and the current production status. Therefore, it’s unable to determine whether the time efficiency is highest or not. This paper presents the optimized strategy of prepress file sorting output. By adopting the SPT rule to arrange files and ranking files from short to long in terms of their processing time, this strategy will minimize the average flow time. This method will reduce file footprint in the workflow, minimize the idle time of each process and result in saving flowing funds and efficiently processing files. In addition, by the means of taking deliver time into account, a ranking model was created, which could avoid the situation that files cannot be delivered on time when it comes to deadline. When setting the minimum processing time as a goal, The strategy neglect those steps that spend less time and processing steps whose time spent has almost no change after file sorting. The flow chart of optimization of file stream sorting is shown in Figure 5. To optimize the sorting of prepress file flow, the strategy fully takes into account prepress preflight, printing process and post-press finishing. As the customer preflight can save much time of prepress preflight, both of them are treated as one process.

Figure 5

Flow chart of optimization of preprint file sorting

6 Analysis of Optimized Example

Taking the printing enterprise named H as an example, according to the actual situation of printing production of company H, this paper takes 8 copies of printed files of this company as samples, shown in Table 3, adopting the optimized strategy above to analyze. According to the actual situation of company H, the productive parameters are settled as follows:

1) Suppose that the whole network printing workflow is continuous and has no errors, and simplify the process, which have a very small difference between each other;

2) According to the situation of company H, in actual printing, if a customer doesn’t specify which preflight scheme is to be used, then the time spent of preflight is 3 hours. This paper assumes that the file which doesn’t adopt any type of preflight scheme takes 3 hours for preflight, customer who separately choose quick-type, general-type, stable-type or comprehensive-type preflight scheme spends different amount of time, the separate time spent are 3 hours, 2.598 hours, 2.061 hours, 1.116 hours and 0 hours respectively;

3) According to the situation of company H, the printing speed is settled as 10000 sheets per hour and v is used to represent this speed. Printing coefficients are divided into 5 levels based on the degree of processing complexity, and these 5 levels are 0.2, 0.3, 0.4, 0.5 and 0.6. For the post-press process, the speed of polishing, laminating and binding are 10000 sheets per hour, 20000 sheets per hour, 40000 brochures per hour.

4) The total flow time formulated by customer is a shorten completion time which is shortened by experience, it deduct the time spent of other steps in actual print process.

According to the assumption above and data given by Table 3, the time spent of all processes as shown in Table 4 can be gotten based on the model described in Sections 5.1, 5.2 and 5.3.

Then, strategy is used to the Network printing process to get an order optimization and the best order is gotten: 2-3-5-6-7-4-1-8. Table 5 gives the total processing time and waiting time in the three processes respectively. It takes totally 343.866 hours.

When the files are not optimized sorting, the time consumed in preflight step and in prepress modification step is 3 hours and the total time consumed based on Equation (20) is 381.75 hours. We can see that an appropriate customer preflight solution in can reduce the time consumed in preflight step by (24 - 14.013)/24 × 100% ≈ 41.61%, and it can reduce the time consumed in the whole network printing workflow by (381.75- 343.866)/381.75 × 100% ≈ 10%. It shows that this optimization method can effectively improve efficiency, and it can be applied to real world file management process of network printing.

7 Summary

This paper mainly research on the optimized strategy of customer preflight, prepress preflight and file-sort of network printing workflow. Firstly, in condition of fully considering the acceptability of preflight for customers, this paper investigates the possibility of occurrence of error of 135 preflight projects and sorts these projects in terms of their value of error possibility. In addition, four kinds of customer preflight standards are customized according to the projects’ error possibility. For the customers, adopting the optimized preflight program could minimize the preflight time, achieve effective preflight and then reduce the likelihood of returning delivered files for correction. For the printing enterprises, it will also lessen the workload of preflight and avoid the unwanted time of returning. Secondly, based on preflight tolerance of printing enterprises, this paper presents prepress preflight projects, which could improve efficiency, increase passing rate of preflight and won’t affect production. Finally, during the process of implementing file sorting management model, the simulation sorting of eight printing file samples have shorten the time spent of preflight by 41.61 percent, the time of the whole workflow by 10 percent. The above data indicate that the optimized three-stage strategy has some significance for improving prepress workflow management. Moreover, the strategy is more efficiency when comparing with the present printing process. However, network printing is a complicate workflow that involves many aspects and unstable influence factors, thus the influence of each factor on network printing efficiency and the research of network printing optimization are matters worthy of attention.