Prinergy - intermittant horz black lines on proofs

[pcourterelle]

Hi, large print shop using Kodak Prinergy. An issue has come up when generating proofs. Prinergy is generating imposed TIFFs for final ouptut and proofing. The TIFF is into a hot folder for the output device. Intermittantly, there will be horizontal lines across some of the process and vector images but not all. The black lines do not cross the gutter or extend into the margin between imposed pages. The lines do not appear on all jobs or on all pages within the same job. The lines do not appear on PDFs generated using the same process. The lines show up on the TIFF file itself and on the printed proiof. There are no lines on the final plate however.

The Kodak knowledge base suggests this is memory allocation issue and to reboot the JTP for proofing and/or the server. Been there, done that, and the problem continues. IT also suggests there may be a conflict between the resolution being used for final output and the resolution being used for the proofs. I've tweaked how the latter is being downsampled but this has not solved the problem.

thoughts and recommendations welcome.

Phil

 

[John W]

We sometimes get either fine black lines or fine white lines only in high rez images when ripping ai.eps files through a layout template to an HqRip to one bit tiff. It indeed appears to be a memory allocation error during the postscript stage of the rip process (the recipe is too complex for the chef!). If we simply embed those images, the lines disappear and never reoccur. I'm confused that you say the tiffs are for output and proofing, show in the proof but not in the plate. Are the plates also made from the tiffs? How are the tiffs re-purposed for the proof? We use Serendipity Black Magic which proofs the actual plate files using RDT (real dot technology).
John W

 

[PrePressTech]

intermittent lines

intermittent lines

Generally speaking horizontal lines are a memory issue. Memory registers load with data and outputs it at regular intervals based on a clock. If you were to put a screen tint (consistent data) in the image area and try that, it should give you a predictable spacing of said lines. Then if the lines are still there then look at the server (RAM), or the handeling of data that is sending the job to the proofer. It may not appear on the ctp unit since the laser intensity is simply masking the problem. Resolution and screen dot shape changes may let you manipulate the appearance of the artifacting but won't likely fix the problem.
Microsoft Online Crash Analysis has a meomory test utility, or there are any number of other utilities out there. Also make sure the print engine is up-to-date and perhaps reload it.

 

[pcourterelle]

Hi John, and PrepressTech...thanks for the responses.

John, the same files that are used to generate plates are used to generate proofs (both VPs and hardcopy) with a key difference being the proof files are downsampled from 2400 to 360 dpi.

Prepress Tech: if there were a RAM issue would we not see generalized instability in the server rather than just one element of Prinergy? My experience iwth RAM is that it wither works or it doesn't, there's no incremental failure.

What I find odd about this is that the location of the lines appears random. The lines appear on a complex map on one page yet not another, similarly complex map on an adjacent page. Generally speaking the lines only appear on process images and not on vechor graphics or spot colours.

I'll speak with the IT Dept and get them to review/test the RAM in any case.

thank you again

Phil

 

[Joe]

How exactly are you downsampling the files for proofing? I ask because you are only seeing the problem in the downsampled files. And "the same files that are used to generate plates are used to generate proofs" is not really accurate because the plate files are 2400 dpi while your proof files are 360 dpi.

When we were making hard copy proofs we would create imposed one-bit tiffs from Prinergy for the CTP and the proofer using different process templates. The process template for the CTP imaged the one-bit tiffs @ 2400 dpi while the process template for the proofer imaged the one-bit tiffs @ 600 dpi. We never saw any lines like what you described.