Batch grayscale conversion in Acrobat / Pitstop

[Gregg]

I have a backlist catalog with approx 1300 CMYK images that need to be converted to Grayscale. I'm running Acrobat 7 with Pitstop and so far I'm getting a better result by using Acrobat's Convert Color's feature - versus Remapping color with Pitstop, and I'm wondering if I'm doing something wrong with Pitstop.

With Pitstop when I do a global change (using Device Gray), all the images are converted to grayscale, overprinting is kept, but the text that was once 100k goes to 82k, and text that was originally 65k goes to 58k. When I do a global change (using Calibrated Gray) all of the images are converted to a 4/c gray. This is a 2/c job, so that won't do.

Any advice? My assumption is that Pitstop would have more control, and do a better job with the conversions, but I'm not seeing that. My Pitstop color management prefs are left at the default settings. Not sure if that has anything to do with it.

Thanks in advance for any suggestions.

 

[Lukas Engqvist]

What makes you think Pitstop would have better control? ;P

 

[Gregg]

Just figured it was better equipped for that type of project. Am I wrong?

 

[mattbeals]

The conversions in PitStop are a bit odd. For gray conversions you generally get better conversions when color management is turned OFF. The problem you are seeing with the solids going to 82% has to do with the profiles you've got in PitStop's color management preferences. All color transformations/changes go through the CMM. And you can control which CMM is used, host (ColorSync on the Mac, ICS/WCS on Windows), Adobe CMM and LittleCMS. There are a lot of variables... PitStop Color Management explains a bit of it. I need to update it for current versions, but the idea is the same. callas does a better job of it with their pdfToolbox product.

 

[Tech]

Are these 4C images already in PDF files? If not, why not batch convert via Photoshop?

 

[Gregg]

Thanks for the link, Matt.

Tech, I'm working or testing, if you will, with a PDF, but I do have access to the native file and P'shop links. The images are all being exported from a database and used at thumbnail size. I have a feeling I will ultimately do a batch conversion in P'Shop, because I'm not that happy with the conversions thus far. Basically, trying to streamline a project that's quite low on the totem pole.

 

[Lukas Engqvist]

Is it all images or just selected images in the product? I would do the change in Acrobat using Acrobat tools. If it is all images you can use the convert to grrey fixup. Otherwise use the touchup and convert to a correct grey profile (perhaps make one by importing your CMYK profile as grey, in PS: gives you dot gain from black, and then top of the menu in PS coloursettings> Gray profile> save as… and then save with a good name)
Use touchup and right click to view preferences of selected object, change to your custom grey dotgain and don't embedd profile.
If you have mixed stuff the colour converter will do your whole PDF or just selected objects based on colour space text or images etc.
I have very little need to upgrade pitstop, finding touch-up in Acrobat to be more stable. If you need for a particular image you can touch up in photoshop and enhance contrast, curves apply a bit unsharp mask and it will update in the PDF when you close.

 

[Joe]

I have a backlist catalog with approx 1300 CMYK images that need to be converted to Grayscale. I'm running Acrobat 7 with Pitstop and so far I'm getting a better result by using Acrobat's Convert Color's feature - versus Remapping color with Pitstop, and I'm wondering if I'm doing something wrong with Pitstop.

With Pitstop when I do a global change (using Device Gray), all the images are converted to grayscale, overprinting is kept, but the text that was once 100k goes to 82k, and text that was originally 65k goes to 58k. When I do a global change (using Calibrated Gray) all of the images are converted to a 4/c gray. This is a 2/c job, so that won't do.

Any advice? My assumption is that Pitstop would have more control, and do a better job with the conversions, but I'm not seeing that. My Pitstop color management prefs are left at the default settings. Not sure if that has anything to do with it.

Thanks in advance for any suggestions.

Pitstop will convert them with 100K text remaining 100K if you turn color management off in Pitstop as Matt has already suggested.