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Question

Export to PDF with photos in RGB and text in CMYK

Forum|Forum|4 years ago
June 17, 2021
4 replies
8540 views

I need some assistance on how to export to PDF with images in RGB and text in CMYK.

Is this possible?

When I set the export settings to convert to Adobe RGB, the text is also converted to RGB. Is there a way to separate the colour space for images and text?

Thanks in advance for any assistance

Geoff

This topic has been closed for replies.

Brad @ Roaring Mouse

Community Expert

I'm going to suggest an alternative: Create a special spot colour called Text Black (spec'd as 0C 0M 0Y 100K, of course) and assign it accordingly.

This spot colour will carry through to the PDF along with your RGB images, and then each individual RIP can deal with that and convert it to process. Of coourse, you have to inform them that's what you're doing.

rob day

Community Expert

I’m not sure why, but @ozdefy12345678 wants all of the placed images to export in the same RGB space. Also the InDesign files are provided, so the text is already set.

O

ozdefy12345678Author

Participating Frequently

Hi Peter, the Appearance of Black setting only affects PDF exports when the destination is RGB—it has no affect on a PDF/X-4 export where the destination is CMYK.

If the conversion is to RGB and the preference is set to Rich Black, the exported RGB black will be absolute— RGB 0|0|0. If it’s set to Accurate, the exported RGB value will depend on the ID document’s CMYK profile, in most cases the RGB black would be less than absolute black—something like 13|13|13 dark gray. In either case the RGB black is going to convert to 4-color at output.

I assume the reason Geoff wants to get all of the RGB color into AdobeRGB is that AdobeRGB has a wider gamut and doesn’t clip a significant part of the CMYK color space the way sRGB does. But, the only way to take advantage of the larger gamut is to edit in AdobeRGB. A simple conversion from an sRGB image to AdobeRGB doesn’t change the output. The conversion by itself doesn’t expand the image’s gamut, you would have to edit the image’s saturation in order to get access to the wider AdobeRGB gamut.

Hi Rob, you're right about maintining the gamut.

We print for some of the worlds top photographers and they almost always shoot raw and export to Adobe RGB. Because we print to a range of different printers, we like to maintain the gamut of the images until the relevant printer and paper is chosen, and only then convert to the the relevant output profile for that printer/paper combo.

The reason we "force" Adobe RGB is two-fold: it's partly a historical decision that will take some unwinding, but it's also because some photographers choose to work in the really large gamut of ProPhoto, which is unneccisarily large for printing, so it's essential that we convert those to AdobeRGB at export time so they can see the impact of the conversion before sending us the file. As you say, converting from sRGB to Adobe RGB has almost no impact an image.

We also have many thousands of customers, so I can't foist upon them extra techniques like creating spot colours. They need to be able to arrive at our site, download our plugin, get designing, export upload and order without having to talk any technical print language.

I have written a set of Javascript functions that are designed to take all the print-related tasks off their plate. We setup the InDesign document to our specs and we take full control of the export so they can't make any mistakes - most of these customers are experts in photography, but experts in print and PDFs they are not.

We don't do any prepress either - we are a 100% web-to-print business and the 1st time we see a file is when it's on paper.

Our plugin works really well and has been a boon for our business. This thread has been about finessing the export a little by trying to maintain the K-only text.

It was worth a shot 🙂

Geoff

rob day

Community Expert

we have to allow for photographers who will import their photos in a variety of RGB profiles - mostly (but not always) sRGB and Adobe RGB. We therefore have to enforce RGB colour conversion at export time.

The PDF/X-4 would export all RGB images with an embedded profile—images with no profile would get the InDesign document’s assigned RGB profile. AdobeRGB and sRGB are display, not output, class profiles, so if the output device is correctly color managing there would have to be a conversion of the AdobeRGB or sRGB images into the chosen output profile—you shouldn’t need the RGB images to be in the same RGB space.

Also, you are allowing native CMYK color—the default PDF/X-4 exports document CMYK color with no profile, but includes the document CMYK profile as the Output Intent, which is usually an offset press profile (ie, US Web SWOP). Will your output device handle a color managed conversion from a CMYK offset press Output Intent to its output color space? Why do the images have to be RGB, but it’s ok for the native colors to be CMYK if the output isn’t to separations for an offset press?

O

ozdefy12345678Author

Participating Frequently

Here's some more background info which may (or may not) help explain my situation...

All inbound files to our business need to have images in Adobe RGB - this is courtesy of a legacy decision some 10 years back.

We don't accept any CMYK images. We output to a range of presses & printers (Indigo, Epson Inkjet, HP Latex) on a range of papers, and each printer/paper combo has it's own ICC profile. We need to make a single conversion to the relevant output profile on the rip only, and that's why we never convert to CMYK in ID.

Our customers create native RGB InDesign files and any non-AdobeRGB images are converted to AdobeRGB.

All of the above works well and has for years.

The only change I'm trying to add is the allowance for K-only text to remain in CMYK, so we can reap the benefits of printing text from RGB. I can see that the PDF spec allows for a mixture of colour spaces, so I'm trying to the way to achieve this via Javascript in InDesign.

Does that info help?

I appreciate the insights

rob day

Community Expert

We output to a range of presses & printers (Indigo, Epson Inkjet, HP Latex) on a range of papers, and each printer/paper combo has it's own ICC profile. We need to make a single conversion to the relevant output profile on the rip only

The RIP is going to make the conversion from the images’ embedded source space into the output profile—there should be no need to make the source RGB spaces uniform. For RGB driven composite printing, the PDF/X presets leave CMYK as DeviceCMYK—no profile—so it is unlikely document CMYK colors would be correctly color managed when a PDF/X file is output to a composite, RGB driven device.

If you are looking for the flexibility of converting source RGB to different output profiles, why not convert the document CMYK colors except for black into the document RGB space? PDF/X-4 would export those colors with the document RGB profile embedded. That conversion could be easily scripted.

L

Laubender

Community Expert

Hi Geoff,

you could do the conversion of a placed RGB image to e.g. Adobe RGB with:

Edit > Convert To Profile

To get an overview what's going on in a particular document with color and placed images, also if you want to do batch conversions I'd recommend Roland Dreger's Color Script for InDesign; when installing on an English version of InDesign you should see an English UI:

https://www.rolanddreger.net/de/1/farbmanagement-in-adobe-indesign/#

Regards,
Uwe Laubender

( ACP )

O

ozdefy12345678Author

Participating Frequently

so it sounds like it can't be done as a global export setting.

Unfortunately I can't ask my clients to all go through their projects and convert all images to Adobe RGB. For the same reason I'd prefer not to force them to only import Adobe RGB images.

thanks for your suggestions though

L

Laubender

Community Expert

Hi Geoff,

do no conversion with an export to PDF/X-4 and RGB stays RGB and CMYK stays CMYK.

Regards,
Uwe Laubender

( ACP )

O

ozdefy12345678Author

Participating Frequently

thanks Uwe

There is one other ingredient that may make this approach not suitable...

We specialise in photo printing, which is why we insist on photos being exported in RGB. Further to this, we have to allow for photographers who will import their photos in a variety of RGB profiles - mostly (but not always) sRGB and Adobe RGB. We therefore have to enforce RGB colour conversion at export time.

How does this additional info affect your suggestion? I've never dealt with PDF/X

Regards

Geoff

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