Xerox CX manual Quality tab in the Job Parameters window 109

Quality tab in the Job Parameters window 109

Parameter

Trapping

Overprint

Screening

Option

Enable Trapping

Black overprint

PostScript overprint

Dot 150

Description

Applies trapping to your job.

Trapping is a solution that solves misregistration between color separations in both offset and digital printing. This occurs no matter the accuracy of the printing device, and results in white lines around objects on top of a background (in a knock-out procedure) and also between adjacent colors.

Note: If you don't select this option, it does not affect trapping incorporated by DTP applications—for example, Photoshop. FAF should not be used with application-based trapping. In a PostScript file that already contains trapping from the originating application, it is not necessary to use CX print server trapping.

Frame thickness: The desired value for the thickness of the trapping frame. The thicker the frame, the less chance that white areas appear between images.

Protect small text: Text that is smaller or equal to 12 pt. is protected and not framed when the trapping algorithm is applied. You can use this option for small or complex images, since thicker frames can decrease quality by hiding parts of an image.

Ensures that black text prints cleanly within a tint or picture area. The text appears in a richer, deeper black, with the underlying CMY values equal to those of the printed background.

Uses the overprint information that exists in the PostScript file. This parameter also determines whether the DTP application PostScript overprint settings are honored in the RIP.

Screening converts CT (Continuous Tone) and LW (Line Work) images into information (halftone dots) that can be printed. The human eye “smooths out” this information, which seems visually consistent with the original picture. Thus, the more lines per inch, the more natural the image appears. Screening is achieved by printing dots in numerous shapes or lines in an evenly spaced pattern. The distance between the screen dots or lines is fixed and determines the quality of the image. Printers can work with even amounts of toner and still produce a wide range of colors when you use screening. The darker the color, the larger the dot.

In order to print an image on a digital printer or press the color server needs to digitally approximate the grayscale values with different distributions of black and white pixels. This process is commonly referred to as half-toning. Digital halftoning begins by sampling the original image at the printer dpi and constructing digital halftone cells.

Applies a low dot-type screen. The screen of each separation is printed at a different angle.