From Scribus Documentation Project
Spot colors are single ink colors, rather than colors produced by four (CMYK), six (CMYKOG) or more inks in the printing process (process colors). They can be obtained by special vendors, but often the printers have found their own way of mixing inks to match defined colors.
Spot colors may be desired for several reasons:
- Economy: If the document to print contains less than four colors, it may be less expensive to use ready mixed inks than to render them as a mixture of inks. The reason is that less plates are required. This is often used in newsprint, where advertisers may be able to use only black and red, for example. Another common use case is business cards.
- Accuracy: It isn't always possible to equal a certain color with a mixture of inks, especially when they are printed on different materials or with different machines.
- Spot colors allow the printing of special colors that can't be mixed with the usual CMYK inks. The most common examples are out-of-gamut colors (like some very saturated blues and oranges) and metallic inks (gold, silver, copper print, etc.), but other inks, such as fluorescent inks, also exist.
The PDF specification supports the concept of spot colors. In terms of PDF information, a spot color is merely a color reference which is defined by a name. This name is supposed to be known by the printer and will determine which color will be used for printing. A PDF spot color also includes a RGB/CMYK information that may be used in cases where spot colors are not supported, for instance if viewed with a PDF reader. It is up to the user or the color vendor to choose a color that will approximate the spot color as closely as possible.
More on PDF and spot colors in this PDF reference from Adobe (see pages 234 and 532)
Spot Colors in Scribus
Scribus provides a way to generate PDFs with spot colors: it is as simple as going to Edit > Colors > New or Edit menu item and checking the corresponding checkbox in the Edit Color window.
There are several industry standards for spot colors, some of which are only used in certain areas of the world. The most widely used color standard is produced by Pantone.
A spot color set is a list of colors maintained by a company. Each color corresponds to a number (and in some cases a name) assigned by this company.
In terms of software, Pantone (or another vendor's) colors are primarily used as spot colors. To produce a document with Pantone (spot) colors, one has to:
- Choose the color(s) from a spot color swatch (which is absolutely essential).
- Create as many colors as needed in RGB or CMYK color space in in Edit > Colors > New. You should try to match the color as closely as possible if you want to print a proof on an inkjet or laserjet (optional; it doesn't affect the final result that comes from the press...)
- Assign the the correct color names.
- Go to File > Export > Save as PDF menu item, open the Color tab, switch the Output intended for: dropdown menu to Printer and uncheck the option Convert Spot Colors to Process Colors.
- Pass the PDF file to a print shop that supports the vendor's colors.
Even though most color tables contain RGB, CMYK and HTML values for each color, the way the color looks on screen (either in Scribus or a PDF viewer) is irrelevant in offset printing, because it will be printed according to its name.
NB: Since exact color matching requires real world color tables anyway, this is no real disadvantage. It can even turn out to be an advantage, because Scribus users are not mislead about the nature of built-in spot color swatches. It is important to realize that these spot colors refer specifically to the inks used in printing, and are not meant to, nor do they accurately represent the colors you will see on screen or from your deskjet printer.
Other vendors of color standards:
Create Your Own Spot Color Sets
Some programs like QuarkXPress, InDesign or Illustrator come with built-in lists of spot color names and their RGB/CMYK representations. In terms of workflow this feature eliminates the need for steps 2 and 3. However, since there is no real on screen representation, the most important step, which is step 1, is indispensable.
Since you don't need spot color swatches in your software, but rather a real color reference table, you may want to create one yourself. To do this, you need to know how to include your colors in Scribus. Open the file
scribus13x.rc in your
$home/.scribus directory under Linux/UNIX, or in
Documents and Preferences\username under Win32. Open the file with a text editor (a real text editor, not notepad!). At about line 40 you see the list of colors known to Scribus:
<COLOR Register="0" Spot="0" RGB="#f0f8ff" NAME="AliceBlue" /> <COLOR Register="0" Spot="0" RGB="#faebd7" NAME="AntiqueWhite" /> <COLOR Register="0" Spot="0" RGB="#ffefdb" NAME="AntiqueWhite1" /> <COLOR Register="0" Spot="0" RGB="#eedfcc" NAME="AntiqueWhite2" /> <COLOR Register="0" Spot="0" RGB="#cdc0b0" NAME="AntiqueWhite3" /> <COLOR Register="0" Spot="0" RGB="#8b8378" NAME="AntiqueWhite4" /> <COLOR Register="0" Spot="0" RGB="#7fffd4" NAME="Aquamarine" /> <COLOR Register="0" Spot="0" RGB="#7fffd4" NAME="Aquamarine1" />
Copy the first line into a new document in your text editor. Next, you need a color reference. Search for the colors you need. For each color you write a line that looks as follows:
<COLOR Register="0" Spot="1" RGB="#40f822" NAME="MySpotGreen3" />
Note the changes: The value
Spot is set to 1, and the color is a name that will be seen by your printing company. In actual practice, you will need to make sure this name has meaning when your printer encounters it. Incidentally, you do not have to worry about placing your edited line in any precise location in the list, since Scribus will alphabetically sort this for you.
How do you find an approximate color now? That's easy. You can use KColorEdit for example, which will provide you the Hex digits to be inserted after
RGB=#". Another possibility is the Wacker Art RGB Colour Mixer (English and German, requires Java) that will do the same job. If you want or need to find a Pantone color that matches your RGB/CMYK values, try the Color Conversion tool provided online by Peter Ferret. EasyRGB offers a wide range of other color matching systems for online conversion. Once you have included all spot colors you need, save your file (just in case...). Then copy all lines to the clipboard and insert them right before or after the color list in
scribus13x.rc. Now open Scribus, and voilà: Your spot colors appear in the list, marked with a red dot:
Obtaining Spot Color Palettes for Use in Scribus Legally
As long as no open standard for spot colors exists, Scribus users will have to buy a color book by one of the color vendors mentioned above and insert the values and names of spot colors directly into Scribus. For serious work, color books will be a requirement anyway, but that's another topic. There is, however, another way to legally obtain commercial spot colors palettes and use them in Scribus. All you need is a commercial program that contains those palettes. Older versions of CorelDraw e.g. contain Pantone, Toyo and more palettes from the major color vendors and can be obtained for a reasonable price. You can either run them yourselves under Windows or OS/X, install them on another PC you can access legally or even use another version – you a have a licence anyway.
In the drawing program:
- Draw as many vector objects as one spot color palette contains.
- Apply each spot color to one object – most palettes aren't huge, so this is feasible.
- Export the drawing as EPS. Be careful not to convert the spot colors to CMYK during export.
- Create a new document and use File > Import > EPS/PS. You will see all the spot colors with their correct names listed in the color dialog after importing the file.
- Now delete the imported drawing and save the file under an appropriate name, e.g.
- Next, close all docs again. Go to Edit > Colors, choose the palette "Scribus Small" from the drop down menu. Remove all colors except Black (Scribus needs at least one color to work). Then clickImport and select the spoteu.sla file. Now you can see all the spot colors in the color list. Finally, click Save Color Setand save your new palette (for example) as Spot Solid Uncoated.
From now on your spot colors will be available for you in any project. If want to reuse your palette on another computer, just store the file Spot Solid Uncoated from your .scribus folder on a USB stick or a floppy disk and copy it to the respective directory on the other computer.
Some vendors, like Pantone or RAL, even offer free downloads of some or all of their color swatches. If the download contains EPS files, you can use these to import the colors as described above.