Dot gain conversion in Acrobat

[assinippi]

I have a 1000 page plus file coming in that needs to be converted to grayscale and printed offset. So far I have 2 test pages to look at. They were created out of word and supplied as an rgb files by the client. I will need to convert them to grayscale. So far easy. On each page is the client logo as part of a running head and somewhere else on the page a logo fom one of their clients. Unfortunately all these logos have a backgound of RGB 252,252,252 or similar. When I convert them to grayscale I get a scum dot (.4 - 1.2%) that will print. I have been trying to come up with a way of applying a custom dot gain curve in the conversion that will sharpen this scum dot. I have Acrobat 7 and 8, Pitstop 6.5 and Callas pdf Toolbox to work with. In photoshop I can easily create a custom .csf profile with a compensating dot gain curve (works beautifully in Photoshop), but I haven't found a way to load it in Acrobat or the plug ins. Any thoughts?

To save time in I will state that going back to the client and having them fix it is not an option. Like many sales forces, our's does not want to rock the boat.

My other, though maybe less elegant option, will be to creat a sharpening curve on the platesetter. The issue with that is the Spinjet, which is upstream from the sharpening process, will show the scum dot. The issue then is all liability for any issues that we miss and can't proof correcctly, fall on us since we will have to assure the client the issues will be fixed in plating.

Thanks for any and all input (except for "have the client fix it").

[Joe]

Originally Posted by assinippi

I have a 1000 page plus file coming in that needs to be converted to grayscale and printed offset. So far I have 2 test pages to look at. They were created out of word and supplied as an rgb files by the client. I will need to convert them to grayscale. So far easy. On each page is the client logo as part of a running head and somewhere else on the page a logo fom one of their clients. Unfortunately all these logos have a backgound of RGB 252,252,252 or similar. When I convert them to grayscale I get a scum dot (.4 - 1.2%) that will print.

Global change? Or is it an image instead of vector?

What WF are you using? Couldn't you apply the curve in your WF before your proofs?

[assinippi]

Unfortunately they are images and Global change won't edit them. I have a Xitron Extreme rip and the only time I can edit the curve is in the plating/screening process.

i was hoping that someone had a method to apply a sharpening curve when the file was either printed to .ps or when it was re-Distilled.

[local1]

This is something that has worked for me from time to time. . . .

Build an action list in Pitstop which applies a user defined transfer curve to all page objects which are selected by this action list, such as images. The trick is to have a PDF object which already includes the needed transfer function. The easiest way to achieve this is to save an Adobe Photoshop EPS image file which has an embedded transfer curve and to distill it with joboptions which preserve the transfer function (not apply!). Then open the PDF file, select the image with the PitStop selection tool, create a new action list, add a "Change rendering parameter" command and change it to "Change transfer" and click on "Grab transfer from selection". Add any selection commands (if needed) in front of this changing command. Then apply it to your PDFs. You can then either set your workflow to apply transfer curves when it processes the file or re-distill with the transfer option set to apply.

[mattbeals]

Local, that's absolutely the best way to do it with PitStop. Thanks for typing it out so I didn't have to!