I made a PDF (Export as PDF) from a multilayered file. It had transparency (Acrobat > Preflight > List transparent objects). I flattened the file, exported as PDF, and it had transparency. I exported the flattened file to JPG, then exported the JPG to PDF, and it had transparency!
To further focus in on the potential solution or problem, I:
created a JPG in XnView
opened it in GIMP, then exported it as a JPG
closed the file, then opened the GIMP produced JPG
exported it to PDF, using default settings
checked the transparency in Acrobat: "Transparency used." (A, in attachment)
To test this, I repeated the steps using Affinity Photo, I:
used the JPG from XnView
opened it in Affinity Photo, then exported it as a JPG
closed the file, then re-opened the Affinity Photo produced JPG
exported it to PDF/X-4, setting it to permit transparency/layers, if there is any
checked the transparency in Acrobat: "No problems found." (B in attachment)
I have repeated this in GIMP using Print > Print to doPDF, cutePDF, AdobePDF, all with no transparency.
Some printers will reject PDFs with transparency. I am trying to produce a PDF from GIMP with no transparency and no other programs (like Adobe PDF). Is that possible?
Sorry, I loaded the image and clicked attach, but obviously it ain't attached. It showed the details from the Preflight Report, after running List transparent objects.
waltonm: Hi! When you export as PDF, one of the options in the export dialogue is "Fill transparent areas with background color". Do you have that option turned on?
03-26-2025, 07:14 PM (This post was last modified: 03-26-2025, 09:29 PM by rich2005.)
Not 100% sure what we are trying to prove, seems the objective is a pdf that will print "as seen in Gimp 3.0" Not easy for me, especially since I do not have Adobe Acrobat / Affinity Photo ......
A pdf from Gimp 3.0 is PDF-1.7 using a cairo library. An old solution is before exporting to PDF is make a new top layer using Layer -> New from visible. That keeps your layers for future editing (as a Gimp .xcf)
Differences can be seen - left to right Gimp 3.0 <> LibreOffice <> Scribus 1.7
and it shows as having transparent sections,
A flattened image with alpha channel removed looks better but still has a "Soft Mask"
-----
A jpeg export then converted with ImageMagick
magick in.jpg out.pdf
Has no metadata at all - no transparency
These things are funny, so I tried making a "New from visible" layer, then exporting to PDF. No luck. I still get transparency.
I do design and formatting books, most of my clients use KDP (Kindle Direct Publishing, part of Amazon) for printing. I am looking for how I can advise people, who are using GIMP to make their own covers, about making a good print-ready PDF. Having transparency isn't good. As it stands, despite all the features in GIMP, I would have to recommend 100% against using it: which I'm trying not to do.
I've tried Print > Print to > doPDF, primoPDF, cutPDF, AdobePDF . . . these all produce PDF with no transparency, but, I cannot get them to output the correct page size (yes I made a custom size). Print to > did work Affinity Photo, but with some tweaking like have to select Portrait despite the images being landscape.
03-27-2025, 08:04 AM (This post was last modified: 03-27-2025, 08:08 AM by rich2005.
Edit Reason: typo
)
There is the occasional question about KTP Their template has dimensions to 3 decimals which does not always coincide with pixel sizes. One of the common issues is text layers, A Gimp PDF does not embed the font only the font name. The solution - flatten the image - the PDF is then a pure raster graphic. As far as I know the PDF produced was acceptable for printing.
It looks to me that the transparency found by your Adobe software comes from the cairo library used by Gimp. This is not under the control of the Gimp developers, they just use the library. In Gimp 3.0 you get a PDF-1.7 The ImageMagick convert I mentioned, just wraps up the image presented in a PDF wrapper. That makes a PDF-1.3 version.
There used to be in the distant past a Gimp plugin that spooled out an image to ImageMagick to make a PDF. No longer works.
The best (free) tool for making anything for printing is Scribus. which can render PDF in various formats. You might still need Gimp. It can convert your RGB image to CMYK for use in Scribus.
03-27-2025, 03:24 PM (This post was last modified: 03-27-2025, 04:03 PM by waltonm.)
I have been active on the CreateSpace/KDP forums since 2009. I think the cover templates were developed around 2010 or 2011. I don't remember problems with the templates mentioned on the forums. As an aside, the KDP templates are now 600 dpi, and they have reduced the number of pages covered by each template from 10/11 to 6/5 (as I recall). Bookow templates (https://bookow.com/resources.php) are 300 dpi and are made to fit each trim size.
I should say that I always make my PDFs from a JPG. I do this because I have seen PDFs open showing, for a second, prior states for material that was erased, changed, etc. Anything I can do to keep the current state pure and clean, has to be a positive assist when entering the print-on-demand environment.
Separate from this post or the question at hand, KDP Technical Support (therefore Customer Support) claims to have proprietary software to test for transparency, I suspect they use Acrobat. Technical Support claims that JPGs can have transparency (click on an image in a PDF, the blue overlays shows transparency), and that the transparency grid (Preferences > Page Display > Show transparency gird) also shows transparency, although, ironically, it does not show the transparency in JPGs. Whether they are delusional or not, they can block a book for having transparency, and it is impossible to prove otherwise (I've tried).
Also separate from this post, while IngramSpark asks for CMYK and PDF/X-1a or PDF/X-3, KDP will accept almost anything. It consistently prints a tad better (in terms of color fidelity and shadow detail) from sRGB than from CMYK.
Back to the question of transparency, while KDP can find transparency in a ham sandwich, if Acrobat clearly identifies transparency in GIMP produced PDFs, that is asking for problems. How often does this happen? I don't know. All blocking issues come and go in waves, probably related to training seminars (or the equivalent), with each lasting about a 6 months to a year. Not everyone with a problem finds their way to a forum.
I am hoping for a practical way for people, who use GIMP, to generate a PDF without transparency.
(03-27-2025, 03:24 PM)waltonm Wrote: I am hoping for a practical way for people, who use GIMP, to generate a PDF without transparency.
Very verbose, but down to the basics: I think the options have been covered and some transparency might be included in a Gimp 3.0 PDF as a "Soft Mask" If that is not acceptable, then so be it. Gimp is not for you.
I would be interested in what your software says about the attached PDF (it is zipped) A straight forward RGB jpeg from Gimp 3.0 but bundled into a PDF using ImageMagick.
From memory the KDP templates are aimed at vector application (Illustrator) or PS which has some vector support. Not really Gimp which is very much a raster editor. To use Gimp I think you will need a plugin that by-passes the cairo library files and uses some other method, maybe ghostscript.
Quote:...KDP will accept almost anything. It consistently prints a tad better (in terms of color fidelity and shadow detail) from sRGB than from CMYK....
That is good to hear, the local printing company I use, also wants RGB for a 10 colour inkjet. The usual proviso, bright colours are out-of-gamut and muted.
I've attached the report. In case it doesn't appear:
Preflight Summary Report for: castlekeep.pdf
Profile: List transparent objects (Processed pages 1 to 1)
Processed by Walton, Date: 3/27/2025 10:30 AM
Results (Summary) No problems found
KDP only says to open the "Template in your image editing software," which downloads as PNG and PDF. From 16 years on the forum, I only remember one person mentioning using vector art for a cover. Not that aren't many more, but only one that found his way to the forum, or to my attention.
An argument in favor of sRGB art versus CMYK for most digital presses would be that unless you have the correct Profile, converting to CMYK will use a color profile based on traditional CMYK colors. Most of these press are designed to emulate RGB, they have different process colors (as compared to Pantone's process colors), and have a bigger/differently shaped gamut. If you convert to CMYK, without the actual profile, you may be reducing the available color gamut . . . eliminating "out-of-gamut" colors . . . that may be in-gamut!
