Advanced Printing


Color separation is used in the preparation of documents that will print with process-color inks on a commercial printing press. Such documents are usually output to film by a high-resolution imagesetter at a service bureau. You don't need to use the color separation option to print files on a color printer.

PasteUp supports four-color process separation, and uses a color separation mechanism similar to Adobe Separator's. Imported CMYK images are supported by this process.  If you need to use another type of image (e.g. RGB) you can use an application like TIFFany to convert the image to CMYK before importing it into PasteUp.

Spot color separations are currently supported when imported from conforming drawing applications (like Adobe Illustrator or Altsys Virtuoso), although you cannot create spot colors with PasteUp. You can use the process color plates for that purpose if you wish. Simply assign a process color (like Cyan) wherever you want a spot color to appear, then use the Cyan plate from the separation process as artwork for your spot color.

When you open the Separation panel, you may be warned that the paper size is not large enough to include crop marks. When printing color separations for printing purposes, your document must be printed with crop marks and registration marks outside the actual page boundaries. These marks allow the printer to align the color plates during printing, and they mark where the document will be trimmed to its finished size. To make room for these marks, the document must be printed on a paper size that is larger than the actual finished document size.

Emulsion Up/down
The Emulsion check box flips the image from right to left. In the U.S., it is most common for printers to use "right-reading, emulsion down film negatives." To produce "rred negs," check Emulsion Down and Negative before you send the document to a PostScript file or imagesetter. If you are using a service bureau, make sure that they know that you've set up the file in this manner and want to have it output to film.
Crop Marks Checkbox
The Crop Marks check box prints crop marks and registration marks at the edges of the page (outside of the finished page size). These will only be visible if there is enough room on the sheet to print them: the Paper Size (PrintîPaper Choice...) must be sufficiently larger than the Page Size (PageîPage Layout...). The Scale and Layout specified in the Page Layout panel will also affect the amount of space available around the edges of the sheet.
Negative Checkbox
The Negative check box on the Separation panel will generate an output page that is a "photographic negative" image. The colors will be reversed -- black for white, white for black.
Bleed Checkbox
The Bleed check box permits images and graphics to run up to one-half an inch outside of the trim area defined in the Page Layout panel. When Bleed is not checked, graphics and text will be clipped to the page edges. The Paper Size (PrintîPaper Choice...) must be sufficiently larger than the Page Size (PageîPage Layout...) for bleed to be visible.
Halftone Screen Frequency And Angle
Using the proper screen frequency and angle is critical for successful color printing. The parameters must be optimized for the printing press and the output device at your service bureau. Standard values are:


Standard Screen Frequencies (in lines per inch)
newsprint 85
magazines (web or offset) 133
high-quality offset 150, 175, 200

Standard Screen Angles
yellow 90
magenta 75
cyan 105
black 45

Note that the standard screen angles are almost never used on PostScript rips. Many newer rips will intercept standard screen angles and substitute optimized angles; others require you to include their optimized values in your PostScript file. You should not attempt to prepare files for color separation before discussing screen frequencies and angles with both your printer and your service bureau.

Color Plate Preview
Normally color separation plates are rendered in grayscale, because they're used to produce photographic plates, and should only contain black and white. During the proofing process, however, it can be helpful to see the plates in the actual colors of cyan, magenta, yellow, etc. For example, you may wish to print transparencies on your color printer to check that the separations are approximately correct. The Color Plate Preview checkbox will cause the separated plates to retain their actual separation color. Since this is not what you want for production, this option is automatically reset after use, and must be checked each time you print or preview a separation.
Custom Colors
Adobe Systems Incorporated has defined standards for representing custom colors within a placed graphic file. PasteUp supports this convention. Files imported from Adobe Illustrator or Altsys Virtuoso also support this convention. If you click on the Custom plate in the Separation panel, you can choose from any custom colors defined within the document.
Trapping And Overprinting
An object's line and fill each have an Overprint checkbox. When Overprint is not checked, a graphic item that is over another will knock it out -- the area that lies under the upper item will be white. When Overprint is checked, the item's line or fill will print over any items that are underneath. Many times, this is undesirable: a blue rectangle will turn green when overprinting a field of yellow, for example. Used skillfully, however, the Overprint flag is a powerful mechanism for trapping. While there are some general rules for trapping, many printers have requirements specific to the operation of their camera departments or presses. Before attempting to trap using PasteUp, you should have a thorough understanding of what your printer expects.
The overprint flag is preset to true for text. It is difficult to correctly trap type below about 36-point, and most commercial printers will tell you that you should simply overprint it.
For further information about trapping, we recommend the Color Guide manual that accompanies Adobe Illustrator software.
PasteUp honors the overprinting flags set by imported eps files if they adhere to Adobe Separator's compatibility guidelines.


See also

Print Menu