updated for 10.1
The program is specially developed for the generation of films with ink injection printers. The resolution of these printers is very high and capable of completing the majority of jobs with processes that require screen printing.
When producing very fine dithers, the printer can generate "moirés" and small oscillations, mostly produced by the physical resolution of the printer when printing the dither. With the studied correction algorithms, the program can minimize these imperfections by adapting angles and the frequency of the dither. This option is licensed-based.
Preparing Design for Printing
There are 3 possible systems for creating a print:
- Creating a 4 color: The design will be separated in 4 colors (CMYK) or 6 colors (CMYKOG). In order to print them, it will reproduce the original colors, usually with a dither of dot shapes that create the typical "rosette". This system is generally used to reproduce photographs or designs with many colors.
- With spot colors: The design is prepared with a mass of definite colors, even though it is possible to recreate tones of the same color using dithers. Normally, this is used to reproduce designs with only a few colors and to reproduce corporative colors (e.g. Pantone®)
- Combination of the two systems: The design is a combination of the four colors and the spot colors.
The program enables the creation of films with the three systems, but the design has to come prepared to us as we need them. Generally, vector design software is used to create originals, like CorelDraw®, Adobe Illustrator® or Macromedia Freehand®.
How does the program differentiate a 4-Color system or spot colors?
- A photographic image will only be reproduced with 4-Color, except if it has been generated with color layers and it's been saved as a DCS file.
- A vectorial design will be reproduced in 4-Color, except for those objects whose color is assigned to color from a "fixed color palette" (Pantone®, Trumatch®, etc.). So, when we create a design, we should assign the object's colors to colors with a fixed color palette that has a proper name. In the next example, we can see a design composed of 4-Color and two spot colors.
In the cases in which we have a design prepared with colors differentiated for 4-Color and spot colors, we should export the design to Encapsulated PostScript® format (EPS).
An overprint occurs when two adjacent colors overlap, and the color on top takes some space from the color below. This ensures that no white bands between the two colors appear when they are printed. The designer must take this characteristic into consideration, and create a design in which the colors are mounted properly. In the following example, we can see a yellow disk encircled by a black border. To create this design correctly, we use the overprint of black on top of the yellow.
As you can see in the figure on the right, the external and internal lines belong to black color, while the central line belongs in yellow. In the printing process, the yellow will be printed first and then the black, covering a small part of the yellow area.
Whatever the design program used, it needs to indicate, for each object, to preserve the overprint. This will ensure that, when the design is exported in EPS, the required information for each object is included.
The multi-channel images are composed of the normal channels (CMYK) and other additional channels that are normally used for specific colors (for example plain colors or Pantone colors).
The program can also interpret these channels, whenever the document is being saved in PostScript DCS. The most modern versions of program for graphic design and design are compatible with this option (eg. Adobe PhotoShop® 6.0). Each file channel has to be specified with a color and a name for each color so that it can be saved with its name in the document. To open the document DCS in the program, in the window of separations, you will be able to see the channels CMYK more than the special channels that contain the image. In order to select the colors that you can print, you can remove the CMYK if you only wish to print the colors of the other channels.
To access the preferences window for the generation of separations, open the job as Separation Printing. The job will only be opened if we have a bitmap or a vectorial design. The next window will appear.
- Choose mode between CMYK and only K.
- The option to 'Convert spot colors to process colors' indicates that the program should convert all plain inks (Pantone®) to their corresponding CMYK components, which are generated through 4 channels only. The option Negative allows to make a print in negative, that is, what is transparent turns black and what is black turns transparent.
- To 'Apply ICC profile' allows for the specification of color profiles for the generation of the CMYK channels. If we have a color profile that is similar or exactly like the one used by the printing system for film mode, then it will be possible to select and generate the CMYK channels with the maximum guarantee of results. Bear in mind that if we are separating color from an RGB image, only the CMY channels will be produced. If, on the contrary, a section of color is selected, it is certain that the 4 channels CMYK can be obtained. The Linearize black link compensates for the different types of dots that the film/ink may have and ensures that each tone is reproduced correctly. This test can facilitate the printing of gradations of black from 0 to 100. The resulting print is completely uniform with changes in tone from 0-5% to 95-100%. Clicking on the Edit button it will open the linearization window.
Linearization of Black Ink
This option should be used to adjust the printer so that it delivers the black tones we need. The best way to achieve this is to adjust the printer gradations of black and white and calibrate them in percentages.
Visually, the change in tones must be gradual, in both the lighter and darker areas. If it is observed, for example, that from 80% on only black can be seen, then the linearization curve should be corrected approximately at that point.
Once a curve is corrected, a modification name can be assigned to it in the Profile, and Save it. It is advisable to print again the same gradient and compare the results to see if there has been an improvement. Remember that if you use a different film, you will probably have to use a different linearization curve too.
Several methods are displayed from the halftoning list. We should select the desired type and establish the desired characteristics with the Settings… button. Here you are accessing the Angle Screen Settings window.
It is possible to establish for each color the angle of the screen the frequency (l/in, l/cm), and the dot shape, although the most common procedure is to use the same one for all the channels. To select the dot shape, select the list of supporting shapes for inkjet printers. We recommend using round one, even though you can also get good results with the Euclidean.
- To avoid "losing dots" when reproducing the lightest and darkest tones, the program has a controller which eliminates the smallest dots of both extremes in the dither.
- The lightest and darkest dots can be deleted in order to facilitate the print of the design, and this is done by shortening the dot's representation, by moving the scale's edges.
- The Pad-printing option ensures that the darkest areas always retain their dots so that they don't simply appear as a black mass. This is necessary when using films in this printing system. The configurations that we have created can be saved, to re-load them in similar works further on.
The frequency of the dither can be introduced in lines per inch or centimeter. Based on the resolution of the printer, the program calculates the frequency and angles that best approximate what has been introduced. This can be seen by pushing.
Depending on the value of the selected "Super Cell", the adaptations of angles and frequencies will differ.
- The value 1x1 is the one that best defines the shape of the dot, calculating the angles and frequency which best matches the resolution of the printer. However, it can sometimes lose gradations of grey tones.
- The value 4x4 will not define with such precision the shape of the dot, but it generates more gradations of grey tones.
The Pad-printing option ensures that the darkest areas always retain their dots so that they don't simply appear as a black mass. This is necessary when using films in this printing system. The configurations that we have created can be saved, to re-load them in similar works further on.
The stochastic dither disperses the dots, grouping them more if the tone is dark, or separating them more if the tone is light. The size of all of the dots is the same. This type of dither has the advantage of avoiding the Moiré effect between the different colors.
As in most cases, it is not possible to reproduce the size of a dot from a printer, and a larger dot needs to be created. To do this, the program allows the enlargement of the printer's dot to a value in which a larger dot impression can be obtained. Using the Dot multiplier, it is possible to increase the value in microns (127 microns=0.127 millimeters).
Other Separation Options
- The option 'Maintain document overprints' are used to preserve the overprint (solid fill). Clicking on it, you save the areas of the filling that have remained under the other colors, in such a way that the colors that overlap have a margin to allow them to be printed. To preserve the overprint (solid rules). Save the areas of the outline that are underneath other colors.
- The option 'Do not create empty plates' indicates the program that if there is any completely empty channel to discard. In this way, unnecessary media is saved.
- In the Custom settings list, it is permitted to save the configuration of the entire separation window from the previous operation. In this way, it is possible to save varied configurations according to the type of separation required. Next to this list, there are buttons to save or delete the configuration from the list.
Press the OK button on this window to proceed to create the separations. When ready to print the separations, pay close attention to the quality of the print that is configured in the program (print resolution) and the bi-directional modes. Normally, the best results are achieved by selecting the highest resolution and the uni-directional mode. Bear also in mind that if you want to use the auto-distribution function of the program, you must first de-activate the design rotation function, so that the program will rotate only some channels and not others. For the best job results, it is recommended that all channels print in the same manner.
In this tab, options for registration and crop marks can be selected.
- Registration marks: They are signs that are printed in the center of the four sides of the design, and they are used to allow the program to register the different colors at the moment they are being printed.
- Density and calibration bars: Generates the printing of signs for each of the colors of the separations.
- Document Information: Includes information about file name, type of dither, and printing channel.
- Crop marks: They are two marks that are situated in the four furthest corners of the design, and serve as a reference for the final cut of the design when it's already printed.
In the separation window, it will appear a list of all the channels that can be separated. On the left of each color there is a square that can be marked 'checked', indicating the channels that we want to separate. On the right of each color, we are shown information about the dithering that is used for the separations.
Edition of Prepared Separation
Once the separations are done, it is possible to modify several of the design's characteristics relating to size, orientation, and crop marks from the Properties dialogue. Moreover, it is also possible to modify the characteristics relating to the dither, once the separations are ready. To do that we should double click on one of the separations, and a window with the dither configuration will appear. Notice that some other options are disabled at this stage.
Separations Link of Design
All the created separations which belong to the same design are linked to one another. Any change we make in any of these will automatically be applied to the rest of the separations of the same design. In this way, for example, when re-sizing one of the separations, the others will automatically be resized in the same proportion.