Saving a 16 bit PDF from InDesign

[johnb78460815]

Is it possible to output a 16 bit PDF from InDesign?

(I have been asked to supply a 16 bit PDF generated from InDesign!).

My doc is set up with links to 16 bit .psd files (.psd files are 16 bit RGB @ 450 dpi as specified by output provider).

They also insist upon no compression.

Therefore I have created a PDF at:

PDF/X-4 2010 standard

PDF 1.7

450dpi

Not Downsampled

Compression: None

Output: No Color Conversion

Profile Inclusion: Include All

I can't see any options for 16 bit output and it looks as though I'm only getting 8 bit as when I open the PDF in Photoshop it's 8 bit.

Can anyone advise?

Thanks

[Chad Chelius]

I don’t believe it’s possible to maintain 16-bit image format in a generated PDF file. I’ve never heard of anyone trying to do this and am curious why it’s necessary. Can you provide more details?

[Laubender]

Hi John,

what you can try is to open your image in the PDF from Acrobat in PhotoShop.

Now change the image to 16Bit, open the original 16Bit image file with PhotoShop and move the original 16Bit data over to the one opened from Acrobat. Then simply save the opened image from Acrobat. Close the image. Return to Acrobat and check if the image data is 16Bit within the PDF.

FWIW I did not test this workflow.

The other workaround you could try (also not tested 😞

Save the original 16Bit image in PhotoShop as PDF and place that PDF with InDesign.

Best after you checked if the image data remained 16Bit with Acrobat Pro.

If you find that PDF/X-4 export from InDesign will change the bit-depth to 8Bit try other PDF export settings and convert the exported PDF with Acrobat Pro to PDF/X-4. Hm. I cannot see that PDF/X-4 is only allowing 8Bit data.

Regards,
Uwe

[Eugene Tyson]

I was litreally testing that

I had a 16 bit image and an 8 bit image on the same page

I replaced the first image in photoshop - with the 16 bit image

And left the 8 bit image alone

Results from the object inspector

Replaced the 16 bit image and now it's bits/pixel: 64

Original image bits/pixel:32

Seems to have desired affect.

[Laubender]

Laubender  wrote

…

The other workaround you could try (also not tested 😞

Save the original 16Bit image in PhotoShop as PDF and place that PDF with InDesign.

Best after you checked if the image data remained 16Bit with Acrobat Pro.

Here a screenshot from PhotoShop CC 2019 with its dialog Save As PDF with PDF/X-4 characteristics.

I unchecked the option that is set by default that would convert 16 Bbit images to 8 bit ones.

Regards,
Uwe

PS.: Thank you for testing, Eugene!

[Chad Chelius]

Well I'm always happy to be wrong 😉 Again, what is the use case for this?

[johnb78460815]

Thanks. Unfortunately the resulting PDF does not support transparency. I need transparency for my layout.

[Eugene Tyson]

Managed to replace the image in Acrobat retaining transparencies.

Edit the PDF in Acrobat

Open the image in Photoshop

Convert it to 16 bit

Add a new layer to the image

Then drag in your 16 bit image that you saved previously

Delete the original layer

Save as - and it goes into a loop - but you can close and save and it worked for me

Here it is removed from the image above

[Eugene Tyson]

Would like to ask rob day​ and Dov Isaacs​ to weigh in on this.

As Rob is a master with colour with colour; and Dov is the expert extraordonaire at PDFs.

[rob day]

Open the image in Photoshop

Convert it to 16 bit

Add a new layer to the image

Then drag in your 16 bit image that you saved previously

Delete the original layer

Hi Eugene, But then I think you have 16-bits in name only—you don't get extra gray levels when sampling 8-bits up to 16-bits.

You can see that problem in a Photoshop histogram. Here I have an 8-bit gradient that has gaps in the 256 level histogram. If I sample the gradient up to 16-bit, the gaps remain (I still have less than 256 gray levels):

Additional color corrections make the gaps worse despite the 16-bits

[Jeffrey_Smith]

Edit, after viewing your last post regarding transparency, the suggestion I was going to make will not work.

[rob day]

The other workaround you could try (also not tested 😞

Save the original 16Bit image in PhotoShop as PDF and place that PDF with InDesign.

Best after you checked if the image data remained 16Bit with Acrobat Pro.

Hi Uwe, I've always assumed that ID simply will not export 16bits because I'm usually placing images, which always seem to export as 8-bit.

I tested a 16-bit Photoshop PDF placed in InDesign and got a curious result. If I place the file at 100%, don't scale it and export to PDF/X-4, I get 16-bits in the export. If I scale the placed Photoshop PDF in InDesign to something other than 100%, it exports as 8-bit! Wondering if you see the same?

[Laubender]

https://forums.adobe.com/people/rob+day  wrote

… I tested a 16-bit Photoshop PDF placed in InDesign and got a curious result. If I place the file at 100%, don't scale it and export to PDF/X-4, I get 16-bits in the export. If I scale the placed Photoshop PDF in InDesign to something other than 100%, it exports as 8-bit! Wondering if you see the same?

Wow! What a crazy result.

I'll test that later and show the results.

Thank you for reporting that oddity.

Best,
Uwe

[Eugene Tyson]

I cannot replicate your result Rob - I'm probably doing something odd.

[rob day]

Here's my test:

Dropbox - 16Test.zip

[Laubender]

!https://forums.adobe.com/people/rob+day  wrote

Here's my test:

Dropbox - 16Test.zip

Hm…

If I do no color conversion to CMYK, no downsampling and no compression with my PDF/X-4 preset I see no degradation from 48 bit to 24 bit in the output PDF. The effective resolution of the image in the exported PDF from 16Test66.indd should be 451.220 ppi. Rob, in your version of the exported ID66Percent.pdf, the effective resoluton is 300 ppi. So, something happened to the image during export.

My result with 16Test66.indd :

Here my export settings:

No downsampling and compression is off.

No color conversion.

Regards,
Uwe

[rob day]

No downsampling and compression is off.

That's the difference. I was using the default PDF/X-4 preset for both

[Laubender]

Just tested: It's downsampling that will convert from 48 bit to 24 bit.

Compression could be used. I see no degradation with that.

Regards,
Uwe

[rob day]

Compression could be used. I see no degradation with that.

I'm seeing that too.

[rob day]

It looks like you can use transparency and still get the 48-bit if there's no compression, downsampling, the Compatibility is Acrobat 6 or later, and the placed file is Photoshop PDF with 16-bit enabled—lot could go wrong.

Thanks!

[johnb78460815]

Hi, The output provider is insisting upon having 16 bit files as they say get a better result from their plotter. I don't believe it myself and have never had to supply 16 bit to any other provider.

They have output from 16 bit TIFFs in the past but I would rather use InDesign to create the artwork.

[Chad Chelius]

I'd have to agree. I could be wrong, but I don't think a plotter has a resolution high enough for 16-bit to make a difference. Plus the files must be huge!

[rob day]

Hi, The output provider is insisting upon having 16 bit files as they say get a better result from their plotter. I don't believe it myself and have never had to supply 16 bit to any other provider.

Why not ask them to show you the difference—output the same image as 16-bit and then sampled down to 8-bit.

I agree with Chad's #7, they are up against the mechanical resolution of the printer and its screening method. Inkjet printers are not continuous tone, they usually use a stochastic screen to create the illusion of gray levels.

[johnb78460815]

Out of interest, what hardware device/method can actually output a 16 bit file to print that can be differentiated from an 8 bit print by eye?

[rob day]

Out of interest, what hardware device/method can actually output a 16 bit file to print that can be differentiated from an 8 bit print by eye?

Dye-sublimation has the appearance of continuous tone and doesn't use a screen.

Dye-sublimation printer - Wikipedia

Inkjet and offset printing use some kind of screening method to create the illusion gray levels—they are not continuous tone.

With offset it is usually a halftone screen where the smaller printer dots are used to draw larger halftone screen dots, which are modulated in size to create the illusion of gray levels. For a high quality 200lpi halftone screen, the plate maker would need over 3000dpi just to define 8-bit's 256 levels of gray.

Inkjet usually uses stochastic screening where same sized printer dots are spaced at different intervals to create the illusion of gray. The downside of stochastic is it noisy, so most inkjet printers add lighter values of the CMK inks to hide the noise. But they are still up against a resolution limit and its ability to space the printer dots.

Epson has printers with 11 cartridges, but it is still not continuous tone. The P7000 has 4 blacks along with orange & green to extend the color gamut (not gray levels).

Two blacks are alternates depending on the paper surface, the other two are light and extra light black. The three blacks screened might get you more than 256 levels, but not 16-bit's 65536 levels.

On a printer using 3 blacks, a 16-bit grayscale test would probably be the way to see if there's a difference.