Preflight Grayscale Conversion Not Working 100%

[laurag5456310]

So, I have a file that I'm trying to convert to grayscale via Preflight in Acrobat. I run the Analyze and Fix script and some elements are converted but others are not.

I tried doing color conversion as well but nothing seems to change. I have been told this works better in Acrobat 9 but I do not have a license for that version.

[Abambo]

please share the original PDF file with us!

[laurag5456310]

Here is a link to the file.

Dropbox - DailyParagraphEditing_3:4_ibc.pdf - Simplify your life

[Abambo]

Looks like there is no problem to get this in bw!

[laurag5456310]

That's odd because my other coworker tries to do the same thing and it doesn't work for him either. What version of Acrobat are you using?

Here are my Steps:

1. Open file in Acrobat DC

2. Open Print Production

3. Select Preflight

4. Select Convert to Grayscale

5. Run Analyze and Fix

[Abambo]

I just tried with Digital printing b/w:

... and it worked right the first time

and in addition I tried now only the bw convert:

and the result is the same bw... Dropbox - DailyParagraphEditing_3_4_ibc.pdf - Simplify your life

[laurag5456310]

Well, that is a good work around but this is a CMYK job so.. the digital conversion won't be enough. Thanks Abambo​ for trouble shooting with me! I think this is a bug according to the other person on the thread.

[Abambo]

With:

I also needed to do the convert twice...

[Dov Isaacs]

Yeah, but that profile contains other stuff as well. The Convert to Grayscale should do it correctly in one pass! See the workaround I have provided - run Convert to Grayscale multiple times!

          - Dov

[Abambo]

https://forums.adobe.com/people/Dov+Isaacs  wrote

Yeah, but that profile contains other stuff as well. The Convert to Grayscale should do it correctly in one pass! See the workaround I have provided - run Convert to Grayscale multiple times!

          - Dov

Yes. That's not exactly only the greyscale. I've now just tried all I found...And for sure "Convert to" should perform the operation the first time.

But the operations is failing also with more complex documents, like this 76 pages brochure:

This was the second pass! As you see, we are outside of the printing area!

Here is the original data:

The yellow part was not surprising me btw (as a colour) because it is under the advert part...

[Luke_Jennings]

The Preflight fixup Convert color to Grayscale under Color Spaces, Spot colors, inks is working as expected.

(found under the blue wrench icon)

[Stephen_A_Marsh]

Thanks Luke, I believe that this is what the preflight is referencing anyway, so good to know that they are not both broken.

I am still seeing a mix of both CMYK and Grayscale objects after running the fixup, which require a further colour conversion to normalise into a single mode/model.

[Dov Isaacs · Accepted solution]

I grabbed the file and tested it with Preflight.

Using the Convert to grayscale fixup in Acrobat Pro DC (latest version), I got the same results as reported. This is very unexpected and wrong. I then tried applying the fixup a second time (just for the hell of it) on the output of that conversion and surprising enough, what wasn't converted the first time was converted properly the second time.

I've attached the original file, the result of the first conversion, and the result of converting the first conversion.

Thus, workaround for the time being is to apply the fixup multiple times. Yes, this is a bug! I'm submitting to our Preflight group for their analysis and fix.

          - Dov

[laurag5456310]

Thanks Dov Isaacs! I thought I was taking crazy pills! Hopefully there will be a fix. At least there can be a workaround.

[Stephen_A_Marsh]

Even after 2 rounds of preflight convert to grayscale - although everything "looks" gray, half of the objects are K only in CMYK and half of the objects are in gray. A further color conversion to grayscale finally makes everything truly gray if that is the desired result.

[dtemko]

I am desperate to reduce PDF file sizes somehow with this pre-fligh function converting to black and white.  However, when I do so, the file size explodes.  I have gotten a 43 mb file to convert to B&W, but then it explodes to 180 mb.  Help! What am I doing wrong?

[Harry5E34]

I am having the same problem but no amount of repeated convert-to-grayscale and digital-print makes the CMY go away. I put one of the problem files hereL https://drive.google.com/file/d/1JAgcys7cjTPqc0bKJC40dNd6f35zX33n/view?usp=sharing

I am using Acrobat Pro DC version 2020.012.20041. Any tips would be appreciated. Book is supposed to go to printer in a couple of days!!!