As promised, here’s the ICC profile needed for the fix: Coated Fogra39 260 Uncoated (CRPC3) ICC profile.
So, you’ve finished writing your book. You upload the PDF to lulu.com, only to be told that the PDF is “bad.” That happened to me a few days ago with my book The CMake Tutorial. And it took two frustrating afternoons to figure out how to fix it. Why? Because I wrote the book using Asciidoc instead of Adobe InDesign or MS Word, so Lulu’s documentation (and customer support) were completely useless.
To save you the hours of frustration, I’m going to give you that fix today. You’ll be able to fix your PDF in minutes. Of course, there is a caveat, which I’ll give toward the end. But, most importantly: it works.
To be clear, if you’re using Adobe InDesign or MS Word to write your book, then Lulu have you covered. Just look up how to fix the issues in their documentation. But, if you’re like me, and use something else, like Asciidoc or Latex, then keep reading…
The Problems
Here are the warnings that Lulu was giving me:
- Ink coverage – It’s complaining that black areas are using a lot of ink. Basically, the PDF is instructing the printer to make black areas even darker by adding coloured ink on top of the black. This is fine for prints on premium paper, but that’s more expensive. Premium paper makes perfect sense for a photo book. But, I’m printing a technical book, so spending extra for premium paper makes no sense
- Image resolution – It’s warning about low resolution images, which I’m going to ignore for now
- Transparency – Lulu’s PDF processor apparently has trouble with transparent areas, and they want you to “flatten” the PDF
How to Fix the Problems
To fix it you need Adobe Acrobat Pro. I tried to use other tools, and none of them worked.
Open your PDF in Acrobat Pro, go to Tools, and select “Use print production” (you may have to click on “View more” under tools).
Now click “Save as PDF/X.” Click on “Settings” in the save dialog, and choose PDF/X-1a. Be sure to deselect the “Create PDF/X-1a according to the following PDF/X-1a conversion profile” tickbox. You do NOT want any conversion to happen at this point.
Choose a new filename, and click the “Save” button. This will “flatten” your PDF which, in turn, gets rid of the transparency warning.
Fixing the high ink coverage takes a bit more work.
 First, Close Adobe Acrobat. Next, download and install the Coated Fogra39 260 Uncoated (CRPC3) ICC profile (link). Double-clicking on the downloaded file should install it.
This ICC profile limits the ink Total Area Coverage (TAC) to 260%, which is just under Lulu’s maximum of 270%.
Restart Acrobat Pro, and open the file you saved in the previous step. Once again, go to “Use print production.” This time, click on “Convert colors.”
Click the “Convert Colors to Output Intent” checkbox, and select the just installed profile: Coated_Fogra39L_VIGC_260.icc.
Click “OK”, and it’ll convert the entiredocument to the chosen profile. Save this file (use Save as, or Ctrl + Shift + S).
Now upload this final PDF, and both the ink coverage and transparency warnings are gone.
Caveat
Converting to a new colour profile may cause colours to not come out exactly the way you want. If your book is highly visual, then this might be a problem for you.
Of course, if your book was highly visual, then you’d probably go for premium paper anyway, in which case you could have ignored the ink coverage warning and saved yourself a lot of bother.