Exploring the impact of printing processes on print quality

Exploring the impact of printing processes on print quality

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There are many processes in printing. To get a good print, there must be no problem in every process. Conversely, if there is a process that has a flash, it is impossible to obtain high-quality prints. If the printing process is subdivided, there are scanning, group making, filming, proofing, printing, printing, and the like. Below, I will introduce each process one by one and discuss it with everyone.

First, scan

Original quality and color level are important factors that restrict print quality. Whether the color printing and color matching, color matching and color matching meet the requirements of plate making have become the main factors affecting the overall printing quality. In particular, photos, neglecting the requirements of printing and plate making, directly affect the overall quality of printing. The picture is a pen that draws dragons and clears the colors, the colors are rich, the layers are rich, and the pictures are clear and vivid, giving the readers a beautiful enjoyment. It is hard to imagine that a set of manuscripts with severe color casts, lack of tone levels, and virtual deformation will print wonderful effects. A poor quality original can be processed, but it should be clear that the image information can only be picked up on the basis of the original, and the information cannot be reconstructed. Each adjustment will lose a lot of level and color information.

Here, the following requirements are applied to the selected photo manuscript, that is, the color is accurate, the size is moderate, the layer is clear, the definition is good, the hair is not sham, the color is bright, the color is rich, accurate, and lifelike; the contrast is moderate, the level distribution is uniform; The secondary manuscript is preferably a 150-mesh print of the network cable, and it is best not to use it for enlargement; the network download photo has few levels, sharpness, excessive color, low pixel count, and should be used with caution. The original is determined, which is how to scan and process. The types of originals and the range of the originals are different. The content and color are very different. It is the central task of scanning and processing. The basic principle of this work is: faithful to the manuscript, higher than the original and strive to unify the style.

Image scanning is the first step in the photo process. It is the specific step of loyal to the original, and the impact on the quality of the image is decisive. Be as faithful as possible to the original, try to increase the level of faithfulness to the original, and determine the appropriate scanning environment based on the different originals. The original should be carefully analyzed, such as original type, level range, black and white field, color, content, orientation, and size. Some scanners have original document analysis functions, and full use can be achieved with less effort. At the same time, it is necessary to analyze the shortcomings and shortcomings of the original and understand the intentions and special requirements of the editing, so as to adjust and compensate during scanning and adjustment. It should be noted that original analysis is an important task before scanning. Scanner parameter settings fundamentally affect the information pickup status. The scanner must first have a clear and unambiguous understanding of the various parameters of the scanning software and be aware of its impact on print quality. Secondly, each parameter should be carefully set according to the original condition and printing conditions.

In the process of image processing, we must master the following points:

1. picture level adjustment. The purpose of the level adjustment is twofold: one is to compensate the expansion of the dot in the printing process, and the main level is concentrated in the visual sensitive area of 10% to 60%. In the adjustment process, the original tone is maximized. Corresponding to the reproduction of the tone of the printing, in order to make the image clear and true; on the other hand, according to the original content and hierarchical distribution, adjust the high, medium and low-level levels of visual response.

2. school colors. The color correction is to reproduce the color reflected by the original (not the original itself). In the course of operation, the main purpose is to correct the color shift caused by the original or scanning, to ensure the color of the main part is accurate, and to ensure the basic color is accurate. When adjusting the color of the school, first ensure that the screen effect is compatible with the printing effect of the unit. When you check the color, you should pay attention to the specific parameter values of the picture and not just the screen.

3. RGB to CMYK format conversion. The image format used for printing the film must be in CMYK format. Its color separation parameter settings will directly affect the printing effect. The black plate generation range, the maximum ink amount, the color separation mode, and the dot gain are very important in the color separation parameters. It needs to be changed according to the printing conditions, and should be well matched with the printing conditions.

4. sharpening. Sharpening is an effective means of improving image clarity. Sharpening is too small and the level is dull. Too big will make the level too embarrassing. One thing to note is that the content is different and the requirements for sharpening are different. If the scenery can be slightly smaller, the utensils can be slightly larger. From the screening process, sharpening also eliminates the layer loss caused by the screening. At this point, sharpening is by no means a process that can be done or not, but a necessary process for processing images.

Second, the group version production

The group version is an important process for image and text mixing. Standardization and standardization of the group version is an effective means to ensure and improve quality. The impact of this process on quality is mainly reflected in:

1. text, picture, color block, gradual operation is not standardized, so that the layout is too crowded or too loose to affect the overall beauty.

2. Due to the difference in visual effects between the screen effect and the resolution and color mode used in actual printing, the printing effect does not match the imagination.

3. Overprinting is performed by a multi-color fit with a smaller font size or thin line.

4. directly use the RGB format group version to make the picture black and white.

5. Pull the picture during the grouping process to make the picture poor and the output slow. In particular, magnifying the picture has a great effect on the picture. Therefore, the group version should be strictly in accordance with the requirements of standardization and standardization. If the picture must be in CMYK format, the picture size should be changed in Photoshop. Do not pull or deform, and the picture, text block and color block spacing should be standardized; the kerning of the text should not change, making the layout beautiful.

Third, the film to play Xianghe printing version

The film, also called output, includes several processes such as RIP hairline, photo-exposure film exposure, and rinsing and inspection. Controlling this process with data and standardization is an important means of ensuring quality. The main impact of this process on quality is:

1. The text is thick and fat due to the linearization of the output film, the printing effect is too dark, the picture color deviation and the layer reproduction are not good, and the color of the color block is deviated.

2. Due to the exposure of the film and improper washing conditions, the bottom of the film is too large and the density is insufficient. Reflected in the layout is the dirty face, the field is imaginary, the low-key network level is lost, the net, the paste network.

3. Due to the high or low number of screens, the picture is ruined, and the picture is poor.

4. The moiré and color appear poorly due to improper screening angle.

5. The overprinting error and the rule line appear too thick due to the low positioning accuracy of the film, resulting in imposition error.

6. Different layouts of the inconsistent appearance of the parameters are different.

7. Due to improper operation such as washing and inspection, scribes, horseshoe prints, and dirty marks are directly reflected on the surface of scratches, imaginary marks, and dirty surfaces.

Therefore, the following points should be noted during the film output process:

1. Data control is the basis for good film output process control and quality assurance. The data control of the film output has two aspects. One is to ensure the accuracy of the output network, the dot error should be controlled within 2%; the second is the bottom ash after the film is output, the maximum density value meets the requirements, and the bottom ash (D.) should be Less than 0.04, the maximum density Dmax ≥ 3.0. This requires a series of tests on the exposure and rinsing process of the film to find a set of accurate system parameters, and adjust the different batches of raw materials at different times. For different films, through trial and multiple linear adjustments, the film meets the above requirements.

2. Careful operation and careful adjustment. Standardized operations are an important step in ensuring the quality of the output. In the output, it is necessary to ensure that the parameters of each layout are consistent, the number of screen lines meets the printing requirements, the mesh angle does not produce the moiré, and the four-color version repeats the positioning accuracy within 25 μm. The registration cross position, size, and thickness are uniform.

After the completion of the filming task, it is necessary to proof. Proofing has two types of digital proofing and analog proofing. The quality of the film directly determines the effect of the proofing, so how is the film going out, and it has a great influence on the proofing and the printing on the back. Pay attention to the choice of light intensity and exposure time. The solution configuration in the platen machine should also be done as required. Generally, the test can be done first, and then the relevant values are determined.

Fourth, printing

Printing is also a very important process. Of course, there are many technical points.

First of all, mastering and controlling the balance of ink and water is the key to stable and improved printing quality. Ink and water balance is the basis of printing. Only when the ink control is just right, can the printed newspapers be clear and the ink color is consistent, and the overprint can be accurate. The key to mastering the balance of ink and wash is water. Under the premise of not being dirty, the water is controlled to a minimum extent, and the amount of water and the amount of ink are in a relatively stable state. Too little water, not only dirty, but also the layout is dull, light gray, imprinted, sometimes there will be snowflake points: too much water, there will be a lack of imprint, the text becomes light, the writing is imaginary, no Level and so on. The absolute balance of ink is not there, only a relative balance. In order to stabilize the ink color balance, it is required to do the following in practical work:

1. Pay attention to the proportion of the dampening solution. The dampening solution currently used by our company is mostly DSC dampening solution of a company in Guangzhou and dampening solution of a company in Shanghai. The ratio of the equipment is generally 2% to 2.5%, and the water temperature is controlled at around 16 °C. The pH value is 5.5. ~6.5 or so, the conductance value is about 1600, and the salinity is about 0.50 (the tap water in the Donghu area of Wuchang is: the conductivity is 270, the pH is 7, and the salinity is 0).

2. According to the quality of the paper, adjust the supply of ink in time. The smoothness of the paper varies depending on the origin of the paper. The water content of the paper varies depending on the season. Therefore, when printing different papers, adjust the ink balance in time. Generally, the news paper with less smoothness and less paper dust is slightly smaller, and the news paper with more rough and confetti has a slightly larger amount of water. When the machine is running at high speed, the speed is relatively small, and the speed is slightly larger when running at low speed. . This mainly adjusts the ink supply amount according to the general performance of equipment, paper, ink and different conditions indoors and outdoors.

3. Control the environment and temperature and humidity of the workshop, which is conducive to improving the printing quality. Since the moisture of the layout is distributed in direct and indirect form, most of the surface moisture is distributed to the space when it meets the needs of ink balance during printing. In general, the higher the ambient temperature, the faster it will be emitted.

4. When purchasing auxiliary materials, try to meet the needs of ink balance. Ink, plate, air cushion blanket, paper and so on have a lot to do with ink color. The paper consumption ratio is significant, and its quality is considered in terms of its economic aspect. However, the main surface of the plate, ink, etc. should also be kept in the selection of materials. Try to use good materials as much as possible. Under normal circumstances, do not change the brand frequently. Let the workshop be used regularly, in principle, what should be bought, not what to buy.

5. Strengthening the maintenance and inspection of printing equipment is a means to improve the quality of printing. Whether the printing equipment is advanced or not, whether the maintenance and maintenance are kept up is crucial to improving the printing quality. Therefore, in actual work, in order to improve the quality of printed products, it is necessary to strengthen the maintenance and maintenance of printing equipment. Always clean the ink roller, ink tank, water tank, water roller and water tank. This cleaning includes cleaning after the end of each day of printing, cleaning before each color change, and periodic thorough cleaning to prevent ink from remaining in the pores of the surface of the blanket. Otherwise, the film is oxidized for a long time, which reduces the adsorption capacity of the ink and reduces the ink transfer. Frequently remove residual ink in the ink tank and impurities around the ink key to make the ink key freely. In particular, the current remote control ink correction device should ensure the cleaning around the ink keys. Always clean the water tank, water tank and water roller to ensure the smooth circulation of the waterway. Pay attention to the proportion of the dampening water when changing the water, so that the pH value of the water is in a normal state.

6. Regularly check the pressure in the transmission section. As the season changes, the machine keeps running for a long time, and the pressure of each part will change slightly. These changes have a direct impact on the printing quality. Because of the pressure between the printing cylinders, the pressure between the water rollers between the ink rollers is critical to the quality of the print. In particular, the pressure between the ink rollers is more severe with the seasons. Under normal circumstances, in March and November each year, in the two months when the climate change is particularly obvious, it is necessary to carry out a large adjustment of the pressure of the rubber roller. The machine and maintenance personnel must check the rubber roller pressure and the roller pressure once every half month, and find that the problem can be adjusted and solved at any time.