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Author Topic: Can I export pdf with 16-bit images?  (Read 361 times)

fortiernor

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Can I export pdf with 16-bit images?
« on: March 29, 2018, 01:46:28 am »
I am trying to use Scribus in order to layout images (photos) on a page for printing. Images are tiff 16 bits per channel, exported from Darktable (tiffinfo confirms 16 bits).
However when I export the document to pdf, pdfimages tells me they are 8 bits per channel. It also reports image size as 56 Mb each (within the pdf), whereas the original tiffs are 118 Mb each. Exporting as tiffs from Darktable at 8 bits per channel yields an image about the size reported by pdfimages, so it does seem the images are converted from 16 bits to 8 bits as they are imported into Scribus or upon export to pdf.
Changing the pdf version for export does not affect that behaviour.
Is Scribus supposed to import and export 16-bit images or does it only support 8 bits per channel images? Or is there something I am missing?
Thank you!

RodneyLee

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Re: Can I export pdf with 16-bit images?
« Reply #1 on: March 29, 2018, 02:03:51 am »
isn't there a setting to limit image size?

mnawij

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Re: Can I export pdf with 16-bit images?
« Reply #2 on: March 29, 2018, 03:27:34 am »
Just curious, why do you need to save as 16bit?  Only the most newest presses and RIP software can handle this level of output if you are trying to print and if not printing it does not improve the quality in my opinion unless viewed on a newer high end monitor/tv/display.  The RIP I have is only 4 years old and it cannot handle 16bit, it downsamples them to 8bit for film/plate output.  Now I do not know about large format printing, I think I read that 16bit improves quality when enlarging photos for printing large banners/posters.

Regards,

mnawij

fortiernor

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Re: Can I export pdf with 16-bit images?
« Reply #3 on: March 29, 2018, 04:22:17 pm »
The 8-bit vs 16-bit printing debate is way larger than the question I'm asking... Let's just say I shoot 14-bit raw images and process them in 32 bits per channel (bpc), and would like to print (on an Epson P800, up to 17" wide) at the highest quality possible.
I use the Turboprint driver and I am looking for a way to avoid using Gimp for printing, as it only supports 8 bpc (the 2.9 development release supports higher bit depth but is a nightmare to maintain on Archlinux).
For single images I export directly as pdf (16 bpc) from Darktable and print using gtklp, but I need a way to assemble smaller images on a single page and export as a pdf document, to save on paper.
Hence my question about Scribus and 16 bpc images in pdf.

mnawij

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Re: Can I export pdf with 16-bit images?
« Reply #4 on: March 30, 2018, 02:19:01 am »
My suggestion would be to try talking with Pat David if you can:  https://patdavid.net/about/

He helps out as an evangelizer with Gimp but also is a photographer who uses opensource tools, or chat up the members up on Gimps IRC, forums or their Facebook page, lots of photographers over there.  I apologize but I really do not know about Scribus and the max bit level on placed photographs.  You might even try filing a bug on Scribus' mantis page requesting higher bit depth on placed photos and see what response you get.

cheers,

mnawij

fortiernor

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Re: Can I export pdf with 16-bit images?
« Reply #5 on: March 30, 2018, 07:06:44 pm »
It seems this has already been reported as a bug:
https://bugs.scribus.net/view.php?id=2064
The bad news is that the bug was reported in 2005 and reassigned in 2014, so I won't hold my breath...
Thank you!