Photokit Sharpener 2 output to halftone

[josquin]

After upgrading to PKS2, I immediately ran into an issue attempting to sharpen for a full-colour offset printing job. The printing company runs all jobs at 240 lpi, but PKS2 choices max out at 175 lpi. I am curious as to why this limitation exists, since high quality offset can run as high as 300 lpi. At any rate, my instinct is to sharpen for 120 lpi as this would optimize for exactly half the lines per inch and therefore might result in fewer artifacts or anomalies. Or would applying the 120 lpi sharpening twice work? I am reluctant to do either without input from the developers for fear of screwing up the job: better somewhat under-sharpened than badly or over- sharpened.

I tried using "standard" sharpening in LR3 when I exported the adjusted RAW image as a TIFF since the image was previously fully sharpened in LR, but felt the result would not be sufficient for offset press output to really "snap." I then exported an unsharpened TIFF from LR3 and let PKS2 and opened it in PhotoShop to let PKS2 sharpen it when I ran into this issue.

Couldn't find anything that addressed this in the PKS2 manual or on the forums.

[digitaldog]

240lpi? You sure its not 240ppi? Or that this is a conventional halftone (not stochastic) screen?

[josquin]

digitaldog,

Thanks for the prompt reply.

240lpi? You sure its not 240ppi? Or that this is a conventional halftone (not stochastic) screen?

Yes, I initially questioned that as well, but their production dept. reaffirmed that it is 240lpi, not ppi, and conventional halftone.

They specialize in full-colour postcards and do a lot of work for people (like us) who are announcing art shows and gallery openings.

David


David

[digitaldog]

I’ve never ever heard of a conventional halftone at 240lpi (Stochastic yes but that’s not a conventional halftone).

Who’s the printer?

[josquin]

Andrew,

It's Modern Postcard in Carlsbad, CA. Huge company that prints, addresses and mails, all in-house. I think their bread and butter is direct marketing, but they are the go-to place for many of the artisans in our area who need to mail out announcements. Their quality is first rate.

David

[Mark D Segal]

Have a look at some of these references: a number refer to 240lpi printing - maybe some insight on the specs there: http://www.google.ca/search?q=half+tone+printing+240lpi&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a. There's a Kodak PDF download, and this one seems to suggest the definitions need careful attention: http://qualityinprint.blogspot.com/2009_03_01_archive.html.

[Schewe]

It's Modern Postcard in Carlsbad, CA.

They are indeed claiming 240LPI but it doesn't say if they are using stochastic screening (I think not). If you burrow down you'll see that they suggest 355PPI input resolution from raster files which is really close to the PKS 2 175LPI 350PPI. So set your image resolution to 355PPI and use the 175LPI sharpener...

[josquin]

Jeff,

Yes, they are requesting all images at 355 ppi, which is how I set it up. So I will take your advice and output for 175 lpi.

Thanks, Andrew and Jeff, for the very fast responses.

David

[Schewe]

Yes, they are requesting all images at 355 ppi, which is how I set it up. So I will take your advice and output for 175 lpi.

Let us know how things turn out...

[josquin]

This is a rush job--I'm paying extra for one-day production and next-day air shipping. As speedy as you guys were in addressing this, the printer's prepress department already had the file and was preparing it to run while I was sorting this out. I gave them the go-ahead to do their own output sharpening on the image based on their assessment of the file and their knowledge of the output characteristics of their press. In the end, I was afraid to hold things up by insisting that they wait for my own updated sharpening.

So its disappointing that I don't have the opportunity to test this right away and report back to you. We do anticipate doing more work with these people, so I'm sure there will be other opportunities. I'll keep you posted.

Thanks again for your remarkably fast responses!

David