(v13) Overprinting user parameters and operators

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

This section describes the overprinting user parameters and operators.

Overprinting user parameters

OverprintICCBasedBoolean user parameter

Default: false

If the OverprintICCBased user-param is set, allow the non-zero overprint mode of CMYK ICCBased color spaces if the ICC profile matches the first output profile found in setreproduction. This happens:

if currentreproduction has no profiles, and the OverrideCMYK setinterceptcolorspace attribute is true. In the HMR RIP, this means a No Color Management setup with the Override color management in job set.
if currentreproduction has profiles, and the OverrideCMYK setinterceptcolorspace attribute is true, and the profile chosen from currentreproduction matches the DeviceCMYK profile from setinterceptcolorspace. In the HMR RIP, this means a ColorPro setup, with the same profile in both the input and output profile slots.
if the job is being processed as PDF/X-3+, when a CMYK ICCBased color space matches the OutputIntents profile.

OverprintProcess (Color Separation)

Boolean user parameter

Default: true

If true, a zero-valued color component in a process color separation overprints when overprinting is turned on (with true setoverprint) and the PostScript-language color space is set to DeviceCMYK. The setcmykcolor operator treats all negative operands in the normal PostScript-language way (that is, to round them up to zero).

If false , a zero-valued color component in a process color separation will always knockout. However, if any –1 operands are given to setcmykcolor, the corresponding components are overprinted if overprinting is turned on, with true setoverprint. Only –1 is special; other negative values are treated as normal. The Level1Separator procset uses combinations of OverprintProcess and –1 operands to setcmykcolor to implement setcmykoverprint.

OverprintBlack (Color Separation)

Boolean or Name user parameter

Default: false

If false, overprinting only occurs as for any other process color.

If true, any solid black object (except solid black pixels of images and shadings) will be overprinted, even if setoverprint is false. An object is “solid black” if the object's color space and color values match the same conditions for black preservation. (For information see (v13) Black preservation). Typically, the Black component must be 100%, and other components must be 0%. The 0% components are implicitly overprinted.

OverprintBlack is not applied to process components if the color is converted to a space where there isn't a Black component. This is seen on some non-standard devices. It also happens in transparency jobs when an object is painted into an RGB blend space. RGB transparency groups are common in PDF. However, spot components of solid black objects are still overprinted.

From v11.0r1 OverprintBlack accepts a new option /Knockout. If the value is /Knockout, solid black objects (except solid black pixels of images and shadings) knockout, even if setoverprint is true.

In traditional print it is common to force black items to overprint when printed on a colored background, to avoid the risk of white lines appearing round it if there is any misregistration on press. However, with UV inkjet printing, the ink for small overprinted black objects has a tendency to “float” on top of inks that have been jetted earlier but are not yet cured, distorting both the black object and anything printed in the underlying colors. By using the /Knockout option you achieve much better results by forcing the black to knockout, which also helps with using less ink. Registration should be good enough because of the natural tendency of the ink films to coalesce with any other unpinned ink film around them because of surface tension.

OverprintGrayImages (Color Separation)

Boolean user parameter

Default: false

The Default was true prior to Harlequin v13.

The OverprintGrayImages user parameter only affects the output when setoverprint is true. If OverprintGrayImages is true and setoverprint is true, gray images overprint CMY; otherwise CMY is knocked out. If a DeviceGray or DeviceCMYK intercept profile is used in the color setup, the effects of overprinting CMY are simulated in the same way the RIP simulates normal CMYK non-zero overprints.

Overprinting operators

Overprinting with setcmykcolor

cyan magenta yellow black setcmykcolor - Exactly as in [RB2], except that if the OverprintProcess user parameter is false any operand which is –1 is not rounded to 0, but instead indicates that the color component is to be overprinted when overprinting is turned on.

Overprinting with setoverprint

Boolean setoverprint - Exactly as in [RB2]; the definition of overprinting process colors is controlled by the user parameter OverprintProcess.