Four-pass printing (which uses all the cartridges, CMYK) is not automatic when Color/Grayscale is selected in the Print dialog of the LaserWriter 8.3 driver. On the Color LaserWriter 12/600 PS, the printer controller primarily determines whether to switch between single-pass and four-pass printing modes. It does this by parsing the PostScript input stream for any "color information". If found, the printer is placed into four-pass mode by the controller. The following should help in characterizing the manner in which the Color LaserWriter 12/600 PS is placed into four-pass mode:
The Color LaserWriter 12/600 PS WILL be placed into four-pass mode IF:
- The document to be printed contains a bitmapped image, black and white or color (in other words, if the PostScript "image" operator is used).
- It would take an enormous amount of "processing" time in the printer to look at the bitmapped data to check for any color information.
- The document to be printed contains one or more non-black pixels.
- If the entire page has only black and white data, but there is one color pixel in the page, then the printer will go to four-pass mode.
- An EPS file being printed contains any references to color usage.
- If the EPS file uses PostScript "color operators" such as "setcmyk", the printer will go into four-pass mode even if "Black and White" is selected in the driver.
- The document to be printed is a Legal-sized page, and there is only 12 MB of RAM in the printer.
- An application uses anything other than the PostScript "setgray" operator.
Note: An exception to this occurs if only black and white text is being printed. In that case, the printer will use single-pass mode. Otherwise, the reasoning for going into four-pass mode is strictly for less memory usage.