flatten

[skunkworks]

Creating a paperback cover. Instructions from Amazon say:

Quote:Image color, size, and quality. Images should be in CMYK color to ensure your cover looks good in print. All images should be sized at 100%, flattened to one layer, and placed in your document at a minimum resolution of 300 DPI (dots per inch).
 
Flatten all transparencies. These can cause the file to print with missing or distorted content.

More explanation would be great as well as how to accomplish these tasks.

[CmykStudent]

Hi! You can use the "Flatten" command (Right click on the layer in the dock and choose "Flatten Image" at the bottom). This will merge all layers into one and remove transparency (filling it with your current background color). You can change the resolution by using the "Print Size" menu under Images.

GIMP 3.0 supports exporting as CMYK in several formats (TIFF, PSD, JPEG, etc). Make sure to check the "Export as CMYK" box in the dialogue when you do, and also export metadata to retain the resolution.

[skunkworks]

(08-11-2025, 02:21 PM)CmykStudent Wrote: Hi! You can use the "Flatten" command (Right click on the layer in the dock and choose "Flatten Image" at the bottom). This will merge all layers into one and remove transparency (filling it with your current background color). You can change the resolution by using the "Print Size" menu under Images.

GIMP 3.0 supports exporting as CMYK in several formats (TIFF, PSD, JPEG, etc). Make sure to check the "Export as CMYK" box in the dialogue when you do, and also export metadata to retain the resolution.

Thank you. The final file must be a PDF. There is a layer filled with the background color. Should each of the half dozen or so layers be flattened, as you suggested? What steps are taken to get the PDF?

[rich2005]

(08-11-2025, 03:25 PM)skunkworks Wrote: ....The final file must be a PDF. There is a layer filled with the background color. Should each of the half dozen or so layers be flattened, as you suggested? What steps are taken to get the PDF?  

Be prepared for a steep learning curve.  The first thing is the usual advice. Save your work as a Gimp .xcf file or you will regret.

Second is Gimp 3.0 PDF has improved but it does make large PDF files - it is basically a single graphics image embedded in a PDF wrapper.

Some gentle hints:
(1) Are you using a provided template.  Usually come with some sort of margin indicators. Check that the required size is correct Image -> Print Size.
(2) Gimp is a RGB editor but if you want a CMYK image then you need to add a soft-proof profile. You might have already done that in Edit -> Preferences -> Color Management, if not then use Image -> Color Management. You do have a cmyk .icc file don't you ?
(3) While you can flatten the whole image Image -> Flatten Image which removes transparency and reduces the image to a single layer, the same is accomplished by exporting as a jpg file. Turn off any template layer you have in case it transfers to the final image.

   

A CMYK PDF. Gimp does not make CMYK PDF's  These days most printers accept RGB, however if you do need one the tool to use is Scribus, the DTP program.  Use your cmyk jpg from Gimp.  Then save in a PDF-x mode which supports cmyk.

   

[skunkworks]

I've already lost sleep and pulled out a few hairs getting to this point. :-) Aargh! Thank you, thank you, thank you for the help. There will probably be more questions.

[skunkworks]

Previously, I executed Control+Merge prior to exporting as PDF. Is this a misstep?

Also, how can a text block be moved a couple of angstroms? :-)

[rich2005]

Did you save all your image layers including text layers as a Gimp .xcf file ?

If you still have that then use the move tool, in move layer mode. ( lots of transparency in text layers, good chance you will move the next layer down make sure you are on the layer, use the keyboard cursor keys to nudge a pixel at a time (shift-cursor key for larger steps)   If you do not have the .xcf then not much you can do. Clone the text out and re-do as a text layer.

   

Always better to flatten the image but can I suggest that (1) Save as an xcf (2) Export to a png or a jpeg where the image is flattened. (3) re-open the exported image for making the PDF.

[skunkworks]

Yes, I am saving the XCF! :-)

Thanks again, Rich! I appreciate you!

[CmykStudent]

rich2005: By the way, we have a pending merge request to allow JPEG compression for PDFs, so that should help with file size in the future: https://gitlab.gnome.org/GNOME/gimp/-/me...uests/2397