Discussion on Film Output Techniques (I)

In the printing industry, as far as traditional printing methods are concerned, the completion of a printed matter generally requires several steps such as manuscript analysis, graphic processing, printing, printing, and postpress processing. The graphic processing is actually the use of some modern equipment (such as cameras, scanners, electronic color machines, color desktop publishing systems, laser imagesetters, etc.) to make the textual information of the original document to meet the printing requirements of the film. The quality of the film has an important influence on the print quality, because the film is the basis for plate making and printing. So how can we get the best film output effect? Here, we will analyze the design, RIP, laser photodischarging, and film processing.

First, design and production

As a design maker, they all hope that their own electronic files can be completely and smoothly output at the output center and get satisfactory films. However, when the output center is outputting, this or that problem often occurs. In fact, many problems are caused by improper design and production. These problems are not complicated, as long as the following aspects are taken into account in the design process.

1. Font

Usually, designers will choose various types of fonts to meet their own design needs. However, there are many types of fonts, and the output center cannot have all the fonts. Therefore, when the design maker uses a font that is not available in the output center, it will appear such as Carefully selected fonts have become problems with other fonts, garbled characters or blanks. Therefore, the design and production personnel should first use Chinese characters such as Hanyi, Wending, and Fangzheng in the industry. Secondly, they should also understand the fonts of the output center so that their Chinese and English fonts are consistent with the existing fonts in the output center. Copy a font to the output center, or convert the text used in the file into a path as much as possible, so that it becomes a graphic, so that the text can be printed normally. However, the generated file contains a lot of curve information, which will cause some pressure on the output device. In addition, PS files can also be generated by themselves and delivered directly to the output center. In this way, there is no need to consider the problem of mismatched fonts, but the premise is to have a certain understanding of the output center RIP and imagesetter. Since not all PS files generated by the layout software and all RIPs are compatible with each other, it is better to select the same printer driver and the same print description file (PPD) as the output center. It is worth noting that before generating the PS file, make sure that the typesetting file is correct, because the generated PS file cannot be changed at the output center.

2. Picture

Image loss, lack of resolution, and bleeding errors often result in the inability to output film or the output of a film that is of poor quality and cannot be used for plate making. These issues are of great concern to the designer. Therefore, during the design process, all the image files should be sent to the output center together, and the correct path and sufficient resolution of the image path can be guaranteed. In addition, the picture should be set to CMYK printing color mode, because other modes are not suitable for printing. Only in this way can a satisfactory film be obtained.

3. Output settings

Designers may not necessarily consider whether the page size of the electronic file matches the size of the output film. If the two are inconsistent, the film will be wasted. In order to save the cost, the output center must change the page settings of the original document. These changes are time-consuming and may also lead to other problems that should not have arisen. If the design and production staff can take this into consideration in advance, it will greatly benefit the improvement of the film output efficiency and the reduction of the document error rate.

In addition, when drawing a rule line, the line type must be “very fine”, the four-color printing timeline should be defined as the CMYK color mode, and the four-color mode should be 100% solid color.

Second, RIP

RIP is the conversion of print data into rasterized images or dots to output film on a laser imagesetter or print on a printer. RIP receives print data in the form of descriptive languages ​​or vector images.

RIP has many output control parameters and must be determined and adjusted before output. Such as: select the file, picture path, exposure value, registration mark, simple and mixed row, missing chart error are all necessary parameters.
The pictures produced by Photoshop software have 8-bit 256-level images. After the photo-taking, all the elements of the picture can be represented. The following formulas must be met:

Control mesh number × 256-2 <Phototypesetter output accuracy

During the output process, RIP parameters should be adjusted first, and after confirming that each value is correct, it can be output.

Three, laser phototypesetting machine

When exporting the film, make sure that the imagesetter is in an absolutely normal and good working condition, and calibrate the laser imagesetter regularly. From the perspective of optimizing the operations of the imagesetter, periodic calibration of the equipment ensures that the equipment produces the correct film density. A small problem with the imagesetter can cause film waste and film drop efficiency. It can also lead to excessive film bottom ash, insufficient density, uneven layout, inaccurate on the ground, missing layers, missing meshes, stencils, etc. .

Phototypesetters mainly include winch type and drum type. The winch type photosetter has a relatively low accuracy. The drum phototypesetter is divided into two types: inner drum type and outer drum type. The outer drum type is faster but the precision is slightly lower. The inner drum type has high precision but slower speed. The experimentally measured high-definition inner cylinder drum phototypesetter output 4 films whose repositioning accuracy can reach ± ​​5μm.

The following methods can effectively improve the output efficiency of the imagesetter.

1. Sometimes changing the direction of the phototype page can greatly increase the imaging speed. For example, pages such as letter paper, with the long edge in the axial direction during exposure imaging, save both exposure time and material.
2. Firstly image the progressing job, remove the problematic job temporarily, and finally deal with the problematic job.