PDF Grayscale Conversion

[ppachen]

I am trying to create an action list in Pitstop to convert a PDF with a scanned image to grayscale. The image mostly contains black text along with a white background. Every action list I've came up with so far has had problems with the white background. It usually converts to something like 94.51% or even 99.61% grayscale (Close, but not exact). I have attempted using several conversion features including "Remap color", "Change color" and "Snap color to a color set". I have also added actions to remove the rendering intent, change the rendering intent to Absolute/Relative/Perceptual/Saturation, remove the ICC profiles, change the ICC profiles, apply transfer functions, and the list goes on.

I'm pretty sure I understand the issue going on: Pitstop is not referencing the white point of the image, so it is not basing the conversion on the white background. Rather, it is referencing some other point, whether it is the black point or somewhere inbetween.

So my question is, can Pitstop do this conversion so that the background is kept at a pure white, or should I be looking at other software to do this?

Thanks for your help!

 

[mattbeals]

Re: PDF Grayscale Conversion

Which version of PitStop are you using? Which platform are you using? If you are using PitStop Pro 7.5.x or PitStop Server 08 you can choose to use one of three color management engings. You can pick from the OS CMM (ColorSync on the Mac, ICS on Win2k & XP, WCS on Vista), or the Adobe CMM (If you install it) or Little CMS (built into PitStop).

 

[ppachen]

Re: PDF Grayscale Conversion

I am using Acrobat 8.1.2 and Pitstop 7.52 on Windows XP. I am currently running an action list that only does three things: Select All, Change Rendering Intent to Relative Colorimetric, and Remap Color. For each time testing, I've changed the rendering intent to Absolute, Relative, Perceptual, and Saturation. They all garner the same results except absolute, which always gives poor results.

So next, I changed it the CMM Engine to Little CMS (Relative colorimetric 73.33%). I then figured I'd try turning the "Enable color management" option off.

I ran a test file and voila, it works!!!

Thanks for your help, I would have never thought to look there!

 

[GregB]

That helps me heaps too. I'm a relative new Pitstop user and have been looking everywhere to find a solution. The first visit to PrintPlanet and it's fixed. Thanks.

 

[the_brain]

FYI

If you disable Color Management in PitStop Professional (Preferences, PDF Profile, Action Lists) you turn to the PostScript rules for converting colors instead of ICC Profiles.

That's this can help in some cases, make it worse in other...

Cheers,
Brain

 

[Purple Cat]

Hi,

As a side note on your comment:

That helps me heaps too. I'm a relative new Pitstop user and have been looking everywhere to find a solution. The first visit to PrintPlanet and it's fixed. Thanks.

Enfocus has an email-based usergroup to which you can subscribe at the Enfocus website here. That's an ideal place to ask this type of question (next to PrintPlanet of course).

Regards,
David.

 

[Lukas Engqvist]

Absolute rendering is only benificial if you are simulating colours from a smaller gamut in a larger gamut which entierly fitts the first.

For full dynamic range mapping Relative is the correct rendering intent. Your CMM will make a difference. If you use Windows or Apple (and several other) CMM you may find impurities in white.
The Adobe CMM usually does a good job.

Why not have a photoshop action before converting? In Photoshop you can cause the white to clip all below 5% and above 95% to make sure black is black and white is white.