Kolory dodatkowe w Scribusie

Kolory spotowe
Kolory spotowe to specjalne jednokolorowe farby drukarskie, w odróżnieniu od kolorów będących wynikiem wymieszania czterech (CMYK) lub sześciu (CMYKOG) farb w trakcie procesu drukowania (tzw. kolorów procesowych). Kolory spotowe sprzedawane są przez specjalistyczne firmy, ale czasami drukarnie stosują własne procedury mieszania farb dla uzyskania zdefiniowanych kolorów.

Kolory spotowe mogą być pożądane z wielu powodów:


 * Względy ekonomiczne: jeśli dokument zawiera mniej niż cztery kolory, użycie gotowych farb może być tańsze od mieszania farb procesowych. Powodem jest możliwość użycia mniejszej ilości płyt. Jest to często stosowane w druku gazet, w których np. niektórzy ogłoszeniodawcy używają tylko farb czanej i czerwonej. Innym typowym zastosowaniem jest druk wizytówek.


 * Jakość: nie zawsze możliwe jest uzyskanie całkowitej zgodności ze zdefiniowanym kolorem za pomocą kolorów procesowych, szczególnie jeśli drukuje się na różnych materiałach i różnych maszynach.


 * Kolory spotowe pozwalają na druk specjalnych kolorów, których nie da się uzyskać z wymieszania kolorów CMYK. Typowym przypadkiem są są kolory spoza przestrzeni barw (np. niektóry bardzo nasycone kolory niebieskie i pomarańczowe) lub kolory metaliczne (złoty, srebrny, miedziany, etc.), istnieją także inne kolory, np. kolory fluoryzujące.

More on spot colours can be found in this Wikipedia article.

The PDF specification supports the concept of spot colours. In terms of PDF information, a spot colour is merely a colour reference which is defined by a name. This name is supposed to be known by the printer and will determine which colour is printed. A PDF spot colour also includes a RGB/CMYK information that may be used in cases where spot colours are not supported, e.g., viewing the file with a PDF reader. It is up to the user to choose a colour that will approximate the spot colour as closely as possible.

More on PDF spot colors in this PDF reference from Adobe (see pages 234 and 532)

Scribus provides a way to generate PDFs with spot colours: it is as simple as going to Edit/Colours/New or Edit menu item and checking the corresponding checkbox in the Edit Colour window.



Standardy przemysłowe dla kolorów spotowych
There are several industry standards for spot colours, some of which are only used in certain areas of the world. The most widely used colour standard is produced by Pantone.

The Pantone colour set is a list of colours maintained by a company with the same name. Each colour corresponds to a name assigned by Pantone.

In terms of software, Pantone colours are – mostly – used as spot colours. To produce a document with Pantone (spot) colours, one has to:


 * 1) Choose the colour(s) from a Pantone colour set (which absolutely essential).
 * 2) Create as many colours as needed in RGB or CMYK colour space in in Edit/Colours/New. You should try to match the colour 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...)
 * 3) Assign the the correct Pantone names.
 * 4) Go to File/Export/Save as PDF menu item, open the Colour tab, switch the Output indended for: dropdown menu to Printer and uncheck the option Convert spot colours to process colours.
 * 5) Pass the PDF file to a print shop that supports Pantone colours.



Although the Pantone colour tables contain RGB, CMYK and HTML values for each colour, the way the colour looks on screen (either in Scribus or a PDF viewer) is irrelevant in offset printing, because it will be printed according to its name.

Some programs like QuarkXpress, InDesign or Illustrator already come with built-in lists of Pantone colour names and 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.

Nota bene: since exact colour matching requires real world colour 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 colour swatches. There are still lots of professional users in the world who believe that the Pantone and other colour swatches in a software really produce spot colours on screen and on deskjets ...

Other vendors of colour standards:


 * HKS, Germany
 * Trumatch, United States
 * ANPA, United States
 * Toyo, Japan
 * DIC, Japan

Jak utworzyć własny zestaw kolorów spotowych
As said above, you don't need spot colour swatches in your software, but a real colour reference table. Next, you need to know how to include your colours in Scribus. Open the file  in your   directory under Linux/Unix, or in   under Win32. Open the file with a text editor (a real text editor, not notepad!). At about line 40 you see the list of colours known to Scribus:

       

Copy the first line into a new document in your text editor. Next, you need a colour reference. Search for the colours you need. For each colour you write a line that looks as follows: Note the changes: The value  is set to 1, and the colour is a (faked, in this case) Pantone colour name that will be seen by your printer.

How do you find an approximate colour now? That's easy. You can use KColorEdit for example, which will provide you the Hex digits that need to be inserted after. Another opportunity is the Wacker Art RGB Colour Mixer (English and German, requires Java) that will do the same job. Once you have included all spot colours you need, save your file (just in case...). Then copy all lines to the clipboard and insert them right before or after the colour list in. Now open Scribus, et voilà: Your spot colours appear in the list: