Some requirements for designers of graphic design in printing
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Graphic design, which can be divided into printed graphic design and non-printing graphic design, based on the carrier of the final work of the work. Printing graphic design has the highest proportion in graphic design work, and the scope and content of design are the widest. The books, newspapers, magazines, albums, bills, bills, etc. that we usually touch are all produced through design and printing. . Printing is a complicated technology. In addition to having a deep artistic background, printing graphic design must also fully understand the printing process and some related knowledge, in order to design a manuscript that meets the printing process requirements with less effort. In fact, some of the works designed by graphic designers usually fail to achieve the desired results after printing. The reason is that the designers do not understand the printing process and do not understand the latest printing technology. The author uses his own actual teaching and learning experience to talk about the requirements for printing graphic designers from the perspective of printing.
About color
1 Use CMYK's printing color standard (color card) to control the color of the work
Most printed graphic designs are now designed and produced using computers. The display of the computer shows the color of R (red), G (green), and B (blue). The three primary colors are colored by color and color, and the color gamut is large. The color of printing is C (green) and M (product). The four primary colors of Y (yellow) and K (black) are colored by the color reduction method, and the color gamut is small. It can be seen that the color rendering of the computer is different from the principle of printing coloring, and the color gamut is different. The final output of printing graphic design is to print C, M, Y, K four colors, so the designer should define, adjust and control the color in the design process, only in this way, the color of the work The appearance will be guaranteed.
In the specific operation, if it is a color continuous tone image (such as a picture transferred from a computer or a photo collected by a designer), how to ensure the color reproduction?
1 Scan color correction and level optimization adjustment input to the computer, from RGB package mode to CMYK color mode, this is a color separation process, its color separation parameters should conform to the characteristics of the printing system equipment, directly using the printed color separation parameters Colored files can be used for output.
2 In the CMYK color space, the CMYK values of some key colors (such as skin color, blue sky, etc.) in the image are corrected to ensure color reproduction during printing. Of course, when the key color adjustment is performed, the color of the screen cannot be used. The corresponding color on the printed color label should be used. It is best to remember the C, M, Y, and K color values of the commonly used key colors, and put the image in the image. The corresponding color is adjusted to the vicinity of this color value. To accurately correct key colors, it's a good idea to keep track of the common colors you're seeing and their CMYK color values.
3 If you are coloring graphics and text, in order to have an accurate color appearance when printing, you must select the desired color on the printing color label and set the graphic object with its corresponding CMYK color value combination. In this way, no matter what color appearance is displayed on the screen, no matter how complicated the output and printing process are, the color appearance of these images has a basic guarantee. The color effect of the final print is determined by the proportion of CMYK components, and on the screen. The colors you see are irrelevant, and the screen color is just a code name for the CMYK combination color.
Printing color is very complicated, and the same set of CMYK color values will vary depending on the paper, ink, printing equipment, printing control parameters, and printers used. Then use this CMYK printing color book to control the color is accurate and reliable? Don't worry, because the skilled output center printing craftsman can reasonably estimate the degree of influence of different situations on the color and make appropriate adjustments, generally can guarantee the chromaticity error within 10%, which is generally acceptable in the domestic market.
2 primary color and spot color selection
The primary colors mentioned here refer to C, M, Y, K and their overprinted colors, also known as printing colors; the spot colors refer to the specific color inks pre-mixed before printing, such as pearl blue, fluorescent yellow, etc. CMYK overprinted colors. Is it CMYK four-color printing or spot color printing? We discuss this issue in three ways.
1 Under normal circumstances, we try to use the primary colors to avoid the use of spot colors. There are two reasons for this: First, four-color printing can combine most of the arbitrary colors, thus giving the designer the greatest freedom of design; second, the spot color Most of the inks are imported inks, and the price is high. When printing, a special printing plate should be made. The printing of the color can be completed by one unit once, which will greatly increase the printing cost. If it is a simple spot color printing, such as newspaper red headings, the cost is lower than the cost of four-color printing.
2 Many well-known companies use certain colors for their logo colors. They must be printed with spot colors. For example, the red color used on the Coca-Cola logo is a spot color. When printing, special color inks must be used for special edition printing. Other unusual color effects, such as fluorescent yellow, pearl blue, etc., also require spot color inks for spot color printing to achieve results.
3 complex design often needs to use the spot color and the primary color to complete the printing and copying. For example, if some printing needs to add the company's spot color mark to the effect of four-color printing, it must add one or two spot color printing. The cost is quite high.
Try to avoid trapping
Trap is a complex professional prepress processing technique. If the printing of the fast printing plates is completely accurate in printing, then when the characters, graphics and images are combined with each other, the ground color may be exposed when the different colors are intersected, that is, “whitening”, registration deviation is inevitable in actual production. (The tolerance for overprinting is 0.1mm), that is, the phenomenon of "whitening" without ink on the printed matter. In order to prevent "whitening" after printing, pre-processing of trapping is done before printing. The principle of trapping is to expand the dark side of the light color in the direction of the color. Whether it is an image or a graphic, as long as there is a clear two-color boundary, it may need to be trapped. The pre-press trapping process will lose the details of the graphic and make it blurry. If it is not handled well, it will lead to very bad results, so the designer should pay attention to the following points:
Image aspect
Some software has an automatic trapping function for two different continuous-tone tangency cuts, creating a transitional “ribbon” with trapping effect in the middle of the two transition color boundaries.
2. Graphic aspect
When the two colors intersect, there are two cases:
1 If the primary colors (printing colors) intersect, if the adjacent colors have enough one of the four colors C, M, Y, and K, trapping can be avoided, such as red (M+Y) and yellow (Y). When the colors intersect, the two share the yellow (Y) version, so there is no need to trap; and if the two colors without the shared primary color intersect, such as red (Y+M) and cyan (C), the two colors must be trapped.
2 When the spot color and the printing color intersect, it must be trapped, and the intersection of the spot color and the trapping process will produce an unexpected third color and seriously affect the work.
In summary, the designer should avoid the use of spot colors when designing the work, or do not let the color block patterns without shared primary colors touch each other.
3. Textual aspects
Usually you can add a small white border to the text, avoid using a small light-colored text (the trap will make it blurry), and use a dark text pattern to imprint on a light-colored continuously changing background. Good choice, this will never be exposed, but it should be noted that large-area embossing is not possible. Large-area embossing will increase the amount of ink, causing adhesion and dirt during the printing process, affecting the printing effect and even difficult to print.
Consider whether to leave "bleeding" to the design paper
“Bleeding” refers to a layout that has exactly the edge of the image that coincides with the edge of the paper. It should be 3mm beyond the edge of the cut for printing and post-printing error. Therefore, when the edge of the work coincides with the edge of the printing material, a bleeding position of about 3 mm should be left for the design document, a bleeding position is added to the printed original, and a bleeding line is drawn. If you do not do this bleeding, the printed product may leave a white border between the edge of the paper and the edge of the printed image.
Determine the design resolution according to the printing process and paper
In the graphic design of printing, the resolution must be determined according to the requirements of the design and printing process, especially the printing materials used for printing (mostly paper), etc., and not all pictures must be adjusted to the highest resolution. rate. For example, newspapers print a lower network cable than a beautiful album, and they have different requirements for the resolution of image files. If the resolution of the image on a newspaper printed on newsprint is adjusted to the same resolution as that printed on coated paper, it is not only meaningless, but instead results in a printing paste. The resolution of different objects in the print computer graphic design is as follows:
1. General newsprint, offset paper printed color or black and white newspaper printing network cable is 60-100 lines, design resolution is 120-200dpi.
2. Generally use offset paper, paper, coated paper, cardboard, whiteboard printed color pictures, such as book covers, pictorials, product advertisements, etc. The printing network cable reaches 150 lines, and the design resolution is 300dpi.
3. High-end books, exquisite albums, high-end advertising prints, printed on high-grade coated paper, printed network cable up to 175 lines, design resolution of 350dpi.
4. Fine treasure books or special valuable certificates, special banknotes, etc., the design resolution can be 400dpi.
Selection of print size
In addition to the design content, the grade of the work, the funding, etc., the size of the printed matter must also take into account the limitations of the printing process and the printing materials.
1. Limitations of the printing process
The size of the printed graphic design, especially the size of the large and small-sized packaging and decorative prints, is limited by various objective factors in the printing process.
1 plate making factor: At present, the output area of each output center and printing factory is more than 710 mm × 510mm-720mm × 540mm, and the largest fully open plate size is only within 1180mm × 720mm. The large computer direct plate making system output plate The format is only 2383mm × 1262mm (such as the screen publishing company's 霹雳 Publishing God 3200), therefore, when designing large format advertisements and color pictures, the size of the printing plate should be taken into account to determine the size. If there is a large format, it can be taken. Dividing the picture, separating the plates, printing, and finally the complete method, but the technical difficulty, high process requirements, and high cost.
Relatively speaking, there are no restrictions on small-format prints.
2 Printing factors The printing machine has certain restrictions on the size of the paper and the printing plate. The PS plate part commonly used in the lithographic offset printing machine is a uniform specification, and the nozzle of the offset printing machine generally needs to leave about 8-10 mm.
In short, the designer should consider the selection of the most suitable printing size of the machine, and leave the necessary process size such as bite, incision, bleeding, patchwork, registering line, dragging the line, etc., to select the finished product size.
2. Printing material limitations
Printing materials are the ultimate carrier of design works, and the cost generally accounts for more than 1/3 of the total printing cost. Choosing the appropriate printing material size and making full use of its area for planning and design is a basic skill that printing graphic designers must possess. The most printed substrates for print-based graphic design are paper, cardboard and plastic film.
1 flat paper
According to the national standard GB786-87, the standards for books, magazines, opening and opening dimensions will be 880mm1230mm, 900mm, 1280mm, 1000mm1400mm uncut single size to adapt to international cultural exchanges, using international standards. The original 787mm1092mm, 850mm1168mm paper version can still be used, but it is a non-standard version of the phase-out.
2 web
The width is 787mm, 880mm, 1092mm, 1575mm, etc., and there are a variety of lifting sizes to choose from.
3 plastic film
There are a variety of opening sizes to choose from, and specific questions should be analyzed.
The opening size provides the designer with the requirement to make full use of the effective layout, and limits the size of the printed matter. The designer should consider the clever use, which can fully express the content of the design and avoid waste.
Understand new technologies and new trends
Printing is a comprehensive discipline with multi-disciplinary and multi-disciplinary integration. It is developing very rapidly. As a designer, it is necessary to learn in time to understand the development of new technologies and materials in the field of printing, such as CTP (computer-to-plate) and high-fidelity. Color printing, digital printing, on-demand printing, and liquid crystal inks, pearlescent inks, new composite materials, etc., to make full use of new materials, new processes, to avoid customers asking for the latest production and processing requirements and you know nothing. Of course, the designer must be honest. If you are not familiar with the processing requirements or if it is theoretically feasible, but the existing printing equipment conditions are impossible, you can easily commit to avoid adverse effects.
Graphic designers should understand that only print-like graphic designs can be adapted to printing and cannot be printed to fit flat designs. Designers may not make a big version, and there is no need to open a four-color offset press, but they must fully understand their interrelated processes from the perspective of print design. Care, patience and humility are essential for print graphic designers. Professional quality. If you can always treat the printing process handsome, the engineering and technical personnel of the printing factory, the printing operators, etc. as your friends and teachers, you will benefit a lot.