Product

Platform

Operating system

Error

Symptoms

Question about the CPC_MirrorScreenWithPage value in the output JTP, why is it set default at TRUE?

We saw a great gain in the output times when we changed this value to FALSE. Could this be true?

And should the CPC_RotateScreenWithPage be set default to TRUE, like we did in Allegro?

Cause

Solution

The mirror screens with pages flag is and was actually supposed to default to true all the time. The printing world is split half-and-half over this, as which way the screening goes depends on how you are used to making plates (film vs CTP). According to the PostScript spec, the actual angles are supposed to be device-dependent, which means that some people are used to flipping angles around for particular workflows to make the angles come out right, while others are used to just getting whatever angles they'd get on their particular output device. Hence the reason for having the switch.

Turning on mirror screens with pages is in general a good thing, as it ensures that screen angles seen on a Spectrum proof will match the screen angles seen on press, regardless of the press process used (offset or otherwise), and whether film or CTP was used to prepare the plates.

I am surprised that you observed a performance increase by changing the mirror screens with pages setting. It is much more likely that the performance increase comes about because of screen caching (i.e., if you have just installed Prinergy or have not used a particular screen setting before, running the same job through the second time at the same ruling, etc., will run faster the second time by anywhere from 5-20 sec overall). The amount of additional time spent actually mirroring screens is on the order of hundredths of seconds.

There is a performance benefit to disabling the rotate screens per page (set to FALSE) and setting the screening mode to override, however. Depending on the job, this can lead to up to a 30% increase in performance, which is why the normal setting for rotate screens per page is false. When rotate screens per page is disabled, the "up" direction is taken as up relative to the way the surface is defined by the job ticket.

It is also very important to get patch 31 applied for a 1.1 system, as there were some serious bugs in the way the screen angles were done prior to this patch.

Permanent fix:

See also

Keywords

output, screening

Technical contact(s)

Gordon Miller

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