CTP application experience (2)

2). Image problems

(1) The RGB color mode is used for color images or graphics.
(2) The image accuracy does not meet the basic printing requirements, such as the resolution is too low.
(3) Images compressed in JPEG format, information on levels and details are lost.
(4) The electrical points or unretouched images after scanning will leave dirty spots on the images.
(5) An error occurred while linking or re-imaging the image.

Solution:

(1) It requires that the design and production staff have the most basic understanding of conventional printing knowledge and have certain aesthetic knowledge.
(2) To achieve standardized management of CTP systems. The process is standardized and the requirements of each process are clearly defined.

Recommended practices:

(1) There are basic requirements for color separation image quality.
(2) The CMYK color mode is generally used in printing.
(3) The image must have sufficient accuracy. For large images, the resolution of a color image is usually 300 dpi or 350 dpi, and the resolution of a Bitmap image is usually 1200 dpi and at least 800 dpi in order to avoid jaggies.
(4) The time-sharing setting should be accurate. The document should faithfully reproduce the original, with high definition, rich details and good levels.
(5) After the electricity is divided, it is required to rectify the color when processing the color to avoid leaving dirty spots.
(6) Do not compress images as much as possible, especially images compressed into JPEG format cannot be used for printing.
(7) Regulate the naming of documents and avoid the appearance of documents of the same name. Be careful when relinking images. Once errors are fatal, don’t take it lightly to avoid major losses.

3). Font problems

For fonts not available in PS fonts, especially Chinese fonts, TrueType fonts are generally used for download, but it is easy to generate missing words or word shifts.

Solution:

(1) Purchase the corresponding PS font or CID font.
(2) Install commonly used fonts for CTP systems and require customers to use the fonts of the corresponding fonts.
(3) For the missing fonts, you can consult with the customer to use an approximate font, but pay attention to the word shift; you can also ask the customer to provide fonts, especially foreign language.
(4) The font is converted into a curve by software such as IIIustrator, FreeHand, or CoreIDraw, and stored as an EPS file format as image processing.
(5) For K100 fonts, traps are generally required.

4). Layout issue

1. For smaller-sized books, double-copies or multi-copies are generally used for printing. However, if the text is arranged in a double-joint or multi-column book, the cover or backing paper is arranged in a single copy, so it is easy to make mistakes when making a large version. Adding a larger workload to the binding.

Solution: The book (including the text, cover, and backing paper, etc.) is arranged in a double-joint or multi-joint book, and the gap between them must be consistent.

2. For printed products, the printing characteristics are not taken into account and the printing requirements are not met. For example, the jobs with large differences in color are printed together.

Solution: Place as many prints of similar colors as possible in the same ink path.

3. For a series of multiple boxes of the same size, when there are two or more laps, it often happens that each large version has to be used as a die because of the gap.

Solution:

(1) Use CAD software to make knife mold lines, and then use them in accordance with the knife mold line layout to ensure that the knife molds are shared.

(2) The different versions of the large version have different influences on the quality and efficiency of printing and binding. The optimal solution can enable the completion of the post process, and the failed spelling can bring unforeseen problems to the post process. Unable to complete or even have to rework. Therefore, the operator of the imposition version must be familiar with prepress, printing, and post-printing procedures. It is advisable to have special personnel to conduct quality checks.

5). Output problems

1. When printing a PS file or PDF file, if the separation mode is selected, the PDF file will be inconvenient to modify.

Solution: Use composite color output.

2. For multi-language editions, most editions are K-color editions, while C, M, and Y editions are shared, or four-color editions are shared and spot editions are divided. In the actual operation, it is prone to confusion.

Solution: Text is available at the exit or the spine. Icon or color as a different version of the logo to avoid confusion.

3. File updates are the most common and deadly problem. Modified application files, if they are not updated in blue paper or large version files in time, use the old files when printing directly, and the printed contents are still old.

Solution: This is a standardization of the management of the CTP system. The key to solving this problem is to formulate a reasonable and standard work flow for the CTP system, strengthen the standardized operation of employees, and achieve unobstructed communication among employees.

6). Color management issues

Color management is the key and difficult point of CTP technology. The ICC characteristic curve that can accurately reflect the characteristics of the device determines the effect of color management. Therefore, creating the ICC characteristic curve becomes the most important task in color management. In the production practice, the author summarizes the following points that need attention:

1. Keep the printing as steady as possible. Enterprises must establish a set of effective printing standards, especially in controlling the printing density and the increase of network points, and require the operator to resolutely execute the printing process, and control each index within the error range.

2. Make sure the digital proofing device is in normal condition. Such as Agfa's Sharpa series, can use QMS (Qualiy Management System) software to detect and adjust the machine, so that the digital proofing device is always in a normal state, and to ensure consistent print results.

3. The IT8 for measurement must have a clean, oil-free surface, and no creases. This has an important effect on whether the ICC characteristic curve accurately reflects the characteristics of the equipment.

4. In theory, different printing conditions correspond to different ICC characteristic curves. However, for the common impressions of the common prints and human eyes, three ICC characteristic curves reflecting the printing characteristics can be set for the three commonly used papers: coated paper, matte copper and offset paper.

5. With the continuous development of technology, color management software should also be continuously upgraded. From the information fed back by the client, the ColorTune used with the Agfa CTP system has been upgraded to version 4.2, which not only accurately simulates the printing effect, but also is very stable. The effect of color management has been a qualitative leap.

7). Printing problems

At this stage, CTP systems are generally used by large and medium-sized printing companies, and most of them have several. More than a dozen or even dozens of different types of presses, such as Heidelberg. Manroland, KBA, Mitsubishi, and Beiren, among others, have both single-sided and double-sided printers, as well as sheet-fed and rotary presses. On the one hand, the size of the plates used in different models will be different. The layout of single-sided and double-sided printing presses will also be different. On the other hand, for CTP systems, once the blue paper is confirmed, Plates can be output. In fact, unless the printing is completed, the print may be printed by different printers. In this way, it is possible to prepare for the release in advance, without causing waste for some reason.

The printing plate of a double-sided printing press can be printed on a single-sided printing press, and vice versa; a large-sized printing plate can be cut into smaller-sized printing plates and printed on a small-format printing press, but not vice versa. Based on the above two points and the actual situation, taking into account the flexibility of production scheduling, you need to pay attention to the following two points: If the paper is large enough, it should be as large as possible by the double-sided printing machine to fight the big version; can not determine the model used, the best out Large-size printing plates, otherwise it will bring unnecessary trouble and loss to production. In addition, we must attach great importance to the inspection of blue paper. Most of the errors can be found on blue paper. As a CTP system manager and related practitioners, we must attach great importance to the inspection of blue paper, so that multiple layers of inspection, check and control, to minimize the error rate.

Nowadays, the development of CTP technology is changing with each passing day. We need to analyze specific issues in the course of continuous learning and exploration, and there are no ready-made formulas and rules that can be copied. CTP technology has many skills. Learning and applying these skills will greatly improve work efficiency. Operators engaged in CTP work must understand the process and technical requirements of the process before and after, otherwise they cannot judge whether the work is correct or not; managers who are engaged in CTP work must be proficient in technology, use various management knowledge, and be involved in complicated and complicated work. Overall planning, mastering and controlling the work process, and making work proceed in an orderly manner.