Precautions For Processing Roll Printing Labels Pictures

Precautions for processing Roll Printing Labels pictures

In order to become a qualified photo processor, the following aspects of knowledge is a must: Basic printing knowledge, basic chromology and color management knowledge, basic printing process of this unit or downstream, basic understanding of "color setting" in PHOTOSHOP, characteristics of commonly used tools, data structure characteristics of types of pictures, reasonable processing steps combined with specific processing content and corresponding correct data control.

It can be said that all the content about the quality control of lithography offset printing is built on the basis of dot and dot transfer, if there is no basic understanding of dot knowledge, at least it is unable to understand the significance of the data changes on the information panel in PHOTOSHOP. If there is no basic knowledge of color science and color management, it is impossible to accurately control the process of color separation. At the same time, as accurate as possible screen display needs to be achieved through color management. "Color setting" is closely integrated with the printing process. Without knowing the back-end printing process, the correctness of the color setting cannot be guaranteed, let alone the correct color separation. The common tools are not just "brightness/contrast", "levels" and "curves". If you only use these three tools, you will not be able to achieve satisfactory visual effects and productivity, and you will lose control of the data for the key content. (I personally do not advocate using "brightness/contrast" tools. This tool does not have a good grasp of the accuracy of data control). As for the characteristics of each tool, I think it should be on the basis of in-depth understanding to make full use of strengths and avoid weaknesses, complementary advantages.

I think the above mentioned should be the foundation of good picture processing work. In fact, the process of image processing is not only the process of visual beautification, but also the process of data control. Only the visual beautification based on reasonable data structure can be realized. Generally speaking, it is not always good to look good on the screen and print out. After all, all the effort up front is for the back end of the print reproduction service, if the print reproduction is not controllable, all your efforts will be wasted.

Related knowledge, screen correction, color separation Settings and other content will also have a special article to introduce to you, this article is limited to the picture processing precautions.

As for photo processing, the characteristics of business and newspapers are quite different. Let's talk about business first.

In commercial applications, the focus of high-quality manuscripts and poor manuscripts in the process of processing is also different, generally speaking, processing personnel to get high-quality manuscripts are already through the electrical classification process, most people will think that all electrical manuscripts must be good, because such manuscripts are often good in visual effects, but to emphasize that, This is a mistake, we must through our own check to determine whether the data structure of the picture is reasonable, because the screen display effect does not fully reflect the picture data, especially on the gray axis. The stand or fall of a picture, not completely depends on the color and level, the gray balance data and the structure of the black edition errors tend to be in the printing process will give you a fatal blow, I at that time, regardless of material loss, I'm afraid it's the inevitable on time, so in advance to check it is very important. Generally speaking, the overall image contrast depends on the total quantity of ink, the length of the black version and its thickness to be determined by the content of the image features, gray balance data is up to the backend printing, if the data deviation is bigger, don't entertain wild hope can be revised in PHOTOSHOP, electric points again when necessary. A good manuscript does not need to do too much adjustment, nothing more than the optimization of details, but the quality of the manuscript is generally not very good, there will be a certain degree of difficulty in processing, at this time the calibration is very important, not after the calibration manuscript often can not ensure the overall contrast and color reproduction. Some people are used to calibrating in CMYK mode, but I think it is inappropriate, so we should calibrate in RBG mode and then separate colors after proper adjustment of brightness and contrast of pictures, because adjusting brightness and contrast in CMYK mode will bring bad effects on gray balance data.

A good manuscript, for business is how to faithfully reproduce, and for the newspaper, any manuscript needs to be re-optimized, nothing more than the number of steps and the difference between easy and difficult.

To be honest with you, newspaper production is characterized by strong timeliness, which requires higher production efficiency per unit time. Moreover, from the scope of adjustment and the range of change, newspaper pictures are far greater than commercial pictures. In this case, the idea of adjusting pictures is more important. First of all, the picture should be analyzed, where there is a problem, what is the nature of the problem, what to adjust first, what to adjust later, what tools to use, and so on, should be thought about in advance. The original copy of newspaper pictures, whether it is the photographer's copy of our newspaper, or the general press release of Xinhua News Agency or online pictures, are basically RGB, and newsprint printing dot expansion is much larger than coated paper, at the same time, in order to ensure the dark level of 4 colors should be used to remove the background color, which determines that the image adjustment process basically needs to improve the brightness. And you have to control the separation. How to maintain the coordination of brightness and contrast in the adjustment process, how to ensure that local adjustment will not affect the overall data structure of the picture, how to ensure the color saturation and neutral gray coordination and unity, all these are to be considered before the actual operation, because fundamentally speaking, the adjustment process of the picture is actually a continuous loss process. For example, the brightness of the light on the surface of the light level is more clear, greater contrast, in fact, at the cost of sacrificing the dark level, but you think the sacrifice is acceptable, and when you have adjusted a number of steps if you find that a previous adjustment is not appropriate, often because of the relationship of time is not willing to back to the original step to readjust, It's about fixing what's already there. In fact, this is putting the cart before the horse. Not only can the original inappropriate place not be repaired, but also may cause undue impact on the place that should not be moved. Therefore, it is very important to analyze the picture before operation.

I would like to say a few words about calibration. For high-quality manuscripts, it is necessary to borrow black and white field in the time sharing, which is necessary from the perspective of restoration. However, for manuscripts of general quality, especially those used in newspaper printing (from the perspective of news, most of the pictures used in newspapers are social and humanistic manuscripts), there is no reduction compared with high-quality artistic manuscripts. It is more concerned with how to enhance the visual impact, which inevitably leads to the adjustment of ideas and methods in contrast to business completely different. Firstly, it is reflected in the calibration. Due to the uneven quality of this kind of manuscript, the black and white fields are directly selected from the picture content. Firstly, the calibration can solve the problem of insufficient overall color bias and contrast to a large extent. There will be deviations in the white field of individual manuscripts during automatic calibration, which will require manual correction, but generally speaking, calibration will lay a good foundation for further adjustment below. We are used to using curves to adjust the picture level, if not first calibration, this adjustment will often cause the dark contrast is not enough. The common tools are not limited to curves and levels. Skilled use of color balance, hue/saturation, color matching, color substitution, alternative colors and other tools will greatly improve the quality and efficiency of image processing. For tools related to color adjustment, the user should at least know the relationship between hue, saturation and brightness, the relationship between different color Spaces, how to control the hypergamut, and the meaning of the parameters in the tool and the impact of the adjustment process on the picture data should also have a certain understanding, otherwise blind use will be less effective.

Finally, I would like to share with you my experience of using the USM sharpening tool. I think the USM sharpening is actually the destruction of the subtle layers, but the visual effect is sharper, so the sharpening step should be put at the end, that is, the sharpening should be done after all the contents of the picture are processed. At the same time, the error of screen display should be taken into account. All the screens we use display content in the form of pixels, and TIFF and JEPG, which are bitmap formats, are also reflected in the form of pixels. Therefore, when the screen resolution is not one-to-one or integer multiple of the image resolution, display errors will occur, and the preview effect we see will be inaccurate if we do sharpening at this time. In addition, the size of the picture displayed on the screen is close to the actual size, which is helpful for the reference of sharpening effect. Of course, it is also essential to have a clear understanding of the concepts of "quantity", "radius" and "threshold" in this tool and the interrelationship between the sharpening process.