Converting CMYK to RGB - How to?

Report · Mar 23, 2009

Posted on Acrobat for Windows Forum this morning - then found this group
- Hope someone can help us...

We are a small non-profit working with adults with developmental disabilities ramping up a very short run color printing service for other non-profits. We print/mail newsletters and brochures and give our adults work to do in our workshop setting.

So we have purchased Acrobat Pro 9.0 - and all we want to do is be a printer of "print ready" pdf'S...

Our knowledge of graphic arts and/or acrobat is very limited - we are just users and again, we want to print out submitted PDF's to our HP high end laser (HP CP6015dn) and give our clients great color printing.

Most PDF files we receive work fine and we output what we see and that is what they get but now one client has sent us a file in CMYK and the color is off. I sent him some other PDF's we have used and he tells us our other files are all RGB so...

Can we take his CMYK file and convert it to RGB and then print it out?

If yes, can you explain it to us very simply?

Thanks

Bob

Report · Mar 23, 2009

Bob,

the conversion of CMYK to any RGB isn't recommended,
but in your case it's perhaps not bad, because you'll
have then the same printing workflow for all PDFs:

Acrobat Pro (tested for 7) > Tools > Print Production >
Convert Colors:
1. Device CMYK > Convert > to Profile sRGB
2. Calibrated CMYK > Convert > to Profile sRGB
3. Grayscale > Convert > to Profile Gamma=2.2
4. Lab > Convert > to Profile sRGB
x Embed Profile as Output Intent
Execute for all pages
Save As by new name

Device CMYK is CMYK without a profile.
Calibrated CMYK is CMYK with a profile.
The CMYK PDF can contain one of them or both.
Grayscale is doubtful.
There is most likely no Lab in the PDFs.
RGB destination space is for simplicity sRGB.

Use eventually p.4 and 5 of this doc for printer
tests:
http://www.fho-emden.de/~hoffmann/a3gencolorhigh.pdf

Best regards --Gernot Hoffmann

Report · Jun 08, 2009

I am in a similar situation. I've just started using InDesign to create a bi-monthly newspaper. The first issue seemed fine -- it printed well. But the printer told me he had to do something to convert all my JPG images to TIFF prior to publication -- because JPG is RGB and TIFF is CMYK, which is what he said his print shop required.

(I should add that I am using ID CS4, and this print shop's clients seem to pretty much exclusively rely on Quark. I did read in the ID book I purchased that you don't need to save to CMYK for print, so perhaps there is something about ID that this printer doesn't know about).

Anyway, the second go-round I saved the file of 36 tabloid-sized pages using TIFF images and CMYK settings, then PDFed that. The printer said there were still formatting issues, but that is not my main issue, since the paper printed fine. My problem is, when I now go to save the document in the "lowest resolution possible" for web display, it keeps giving me an error reading and says my transparency settings aren't compatible with the output selection.

I've tried to go in manually and change the settings back to RGB/JPG, but when I try to PDF it that way it tells me InDesign has encountered a problem and has to close (and needless to say the PDF doesn't produce).

I'd like to know if there's a way to PDF this document at the lowest resolution possible without having to go in and replace every photo with a jpg (and I'm not even sure that would work).

Should I just follow the same directions outlined above? Since it's for web display and not high rez print out put I thought it might be different.

Thank you.

Report · Jun 24, 2009

Paula LA wrote:
I am in a similar situation. I've just started using InDesign to create a bi-monthly newspaper. The first issue seemed fine -- it printed well. But the printer told me he had to do something to convert all my JPG images to TIFF prior to publication -- because JPG is RGB and TIFF is CMYK, which is what he said his print shop required.

Not to be mean, but your printer is not very knowledgeable. JPG and TIFF are image formats. You can have a CMYK JPEG, and an RGB TIFF.

(I should add that I am using ID CS4, and this print shop's clients seem to pretty much exclusively rely on Quark. I did read in the ID book I purchased that you don't need to save to CMYK for print, so perhaps there is something about ID that this printer doesn't know about).

Yes if your printer relies solely on Quark, he's definitely behind the times. You should be able to leave all images jpeg RGB, and output a print ready CMYK PDF, and give that to the printer instead of native files

Anyway, the second go-round I saved the file of 36 tabloid-sized pages using TIFF images and CMYK settings, then PDFed that. The printer said there were still formatting issues, but that is not my main issue, since the paper printed fine. My problem is, when I now go to save the document in the "lowest resolution possible" for web display, it keeps giving me an error reading and says my transparency settings aren't compatible with the output selection.

This may be caused by transparency blend space setting in ID. Try changing that to RGB if you output PDF for web

I'd like to know if there's a way to PDF this document at the lowest resolution possible without having to go in and replace every photo with a jpg (and I'm not even sure that would work).

It is fine to leave links as TIFF. When you output PDF, the images in the PDF result will be JPEG, you don't have to change them in Photoshop.

Hope this helps...

Report · Jun 24, 2009

Thank you! This was helpful in terms of giving me insight into my printer's deficiencies, and also very helpful in terms of concurring that I can leave all images jpg rgb and then simply output to a print-ready CMYK file. (If you have any specific suggestions as to which settings to change to do this, that would be helpful).

I had tried to change the transparency blend settings in the document from cmyk to rgb prior to the PDFing (I think it was an option off the file menu), but that didn't seem to help. I kept getting the same error message. I have a feeling the file may have been corrupted.

I did wind up replacing all the images -- but silly me, I wound up replacing them all with color files (whereas the printed product was mostly B&W). Since this was for web display, I figured unlimited bandwidth, right? Not really! I didn’t' think about the fact that the color images were going to be so much larger than the BW. The PDF wound up huge, at about 20 MB, which I squashed down to 11 MB, but was told that was also too large. The file had to be 5 MB or less, which I wound up doing via a convoluted process of turning every page into a jpg file.

REQUESTS:

1) If you can point me to a link that offers any kind of tutorial on the best method for creating the smallest possible PDF, that would be great.

2) If you can point me to a link -- or offer any insight -- into how to "archive" a print project's ID file, that would also be very helpful. Since the photos are sometimes linked from various locations on a hard drive, just saving the final project folder doesn't really cut it. I imagine the project folder has to be "packaged" and then zipped and saved? That is my best guess. If you have a better method or know of a tutorial, would be appreciated, as are your earlier comments.

Thank you!

Paula Parisi

Report · Jun 25, 2009

Paula LA wrote:
Thank you! This was helpful in terms of giving me insight into my printer's deficiencies, and also very helpful in terms of concurring that I can leave all images jpg rgb and then simply output to a print-ready CMYK file. (If you have any specific suggestions as to which settings to change to do this, that would be helpful).

This can get somewhat complicated. Especially considering RGB - CMYK and you color settings. Color settings I recommend North America Prepress 2. PDF export: PDF/X-4:2008. In the output select "Convert to Destination (Preserve numbers) and set the destination to "Document CMYK" You will have to change the blend space back to CMYK for print output. The good thing is in the event you forget to do that, you should get a warning.

REQUESTS:
1) If you can point me to a link that offers any kind of tutorial on the best method for creating the smallest possible PDF, that would be great.
2) If you can point me to a link -- or offer any insight -- into how to "archive" a print project's ID file, that would also be very helpful. Since the photos are sometimes linked from various locations on a hard drive, just saving the final project folder doesn't really cut it. I imagine the project folder has to be "packaged" and then zipped and saved? That is my best guess. If you have a better method or know of a tutorial, would be appreciated, as are your earlier comments.

1- The PDF export "Smallest File Size" is just that. The only way to get it even smaller would be to lower the resolution (pixels per inch) value in compression tab. Again, this is web output, the destination color is sRGB. So you would have to change that blend setting. I believe if it's CMYK you will get flagged with warning

2. This deals with collecting native files. If you are sending print ready PDF you wouldn't have to do that. But to collect native files use File: Package... tick fonts and links, and all the files will be collected in a parent folder. Let me know if you have problems with this.

On another note you mentioned the printer rejecting your RGB images. If you package you'll gather RGB images. I'm not sure why the printer would have a problem with RGB images, but I believe you mentioned that earlier...

Report · Jun 25, 2009

Thank you so much Rick! This is all hugely helpful.

Yes, as to your mention "on another note" of my printer's rejection of RGB, they indeed requested CMYK and said RGB doesn't work for them. I'm not sure why. I don't really know enough about commercial printing to figure that one out (yet). I do have a feeling this printer is a bit behind the times (what with their fondness for Quark and all).

Regarding your suggested settings: My printer gave me presets that are saved under their own name, "TEN PrePress."

I'm a little confused, because when I access the TEN PrePress settings through the EXPORT or ADOBE PDF PRESETS tabs in the InDesign program, neither generates a menu with a COLOR SETTINGS tab (though I can get one by accessing the TEN PrePress through the Acrobat Distiller).

Under Color Settings, accessed through the Distiller, where you recommend NA Prepress 2 it appears they had me select "None."

Under Color Management Policies (the tab directly below Adobe Color Settings) they had me select "Leave Color Unchanged," (though this does give me the option of selecting "Convert All Colors to CMYK", which sounds like it might be what I want to do).

In the Distiller, there is no OUTPUT tab. When I access the OUTPUT tab through InDesign's ADOBE PDF PRESETS tab (selecting TEN PrePress), I notice they had me select "No Conversion" as opposed to your suggested "Convert to Destination (Preserve Numbers)." (So of course there is no Destination selected, and hence no "Document CMYK," which could be the problem. And perhaps their lack of familiarity with InDesign kind of translated to them not knowing how to instruct me on the proper settings.) I think I'll try the settings you suggest and have them do a "trial run" to see how it prints.

I am going to start shopping around for local (Los Angeles) printers with a better familiarity with InDesign.

I am trying to familiarize myself with Acrobat 9 as well, and am reading the Acrobat 9 PDF Bible 9 (which I need a winch to prop up!) It looks like there are also some online courses and tutorials for using InDesign for Commercial Printing, so I'll check those out.

Your suggestion about the Packaging to archive native files makes sense. I'll try that.

As for the "Smallest File Size," this still falls into the "mysteries of the universe" category! I feel like a formula must exist for the "best" ways to crunch down a file that needs to be taken down further than what the "Smallest File Size" will produce. Some trick, like compressing the photos using a different formula than the type. I'll try your suggestion with the compression tab and will experiment a bit and if I hit on anything revolutionary will let you know (so you can pass it along in your capacity as forum wizard).

Thanks again!

-Paula

Report · Jun 25, 2009

Paula LA wrote:
Yes, as to your mention "on another note" of my printer's rejection of RGB, they indeed requested CMYK and said RGB doesn't work for them. I'm not sure why. I don't really know enough about commercial printing to figure that one out (yet). I do have a feeling this printer is a bit behind the times (what with their fondness for Quark and all).

They're scared of RGB, and taking ownership of the conversion. This issue is often debated. I think the easiest solution is for you to supply a CMYK PDF.

Regarding your suggested settings: My printer gave me presets that are saved under their own name, "TEN PrePress."
I'm a little confused, because when I access the TEN PrePress settings through the EXPORT or ADOBE PDF PRESETS tabs in the InDesign program, neither generates a menu with a COLOR SETTINGS tab (though I can get one by accessing the TEN PrePress through the Acrobat Distiller).

The color settings are an application setting in ID. Go to Edit: Color Settings. You can even use Adobe Bridge (if you have the suite) and go to Edit: Creative Suite Color Settings, this will synchronize all Adobe apps

In the Distiller, there is no OUTPUT tab. When I access the OUTPUT tab through InDesign's ADOBE PDF PRESETS tab (selecting TEN PrePress), I notice they had me select "No Conversion" as opposed to your suggested "Convert to Destination (Preserve Numbers)." (So of course there is no Destination selected, and hence no "Document CMYK," which could be the problem. And perhaps their lack of familiarity with InDesign kind of translated to them not knowing how to instruct me on the proper settings.) I think I'll try the settings you suggest and have them do a "trial run" to see how it prints.

Your printer is in the dark ages. I'm not sure how Distiller figures into it. You shouldn't need Distiller, unless you are printing a postscript file and distilling it. That's not necessary.

Since your printer is so far behind, you might consider PDF/X-3, with the same conversion (Preserve numbers, doc cmyk). This will flatten transparencies in the PDF. But the PDF file size will be larger.

As for the "Smallest File Size," this still falls into the "mysteries of the universe" category! I feel like a formula must exist for the "best" ways to crunch down a file that needs to be taken down further than what the "Smallest File Size" will produce. Some trick, like compressing the photos using a different formula than the type. I'll try your suggestion with the compression tab and will experiment a bit and if I hit on anything revolutionary will let you know (so you can pass it along in your capacity as forum wizard).

I really don't think you'll get it much smaller. Don't go compressing your photo links, ID does that on output. Looking back I saw you have 36 (11x17), that is a lot of large pages. Not knowing the content I'm not sure what's contributing to the file size, you may have a lot of complex vector (AI) art. You could have art beyond the page boundaries that you can't see, sometimes facing pages causes this. (But don't take your document out of facing pages, you could mess up your page layout)

If you have Acrobat Pro to open the PDF, maybe "Reduce File Size" would help, or perhaps the PDF Optimizer.

You could export all your pages as JPEGS, bring those into a blank ID doc and output that. But then your type would be low quality (which I guess would be OK for thumbnails, but not for reading...)

You're too kind calling me forum wizard, I'm pretty far from that. I got ripped to shreds yesterday in my Photoshop Mac post "Assigning Profiles vs. Converting to Profiles". A lot of good color management discussion there, and also ID "RGB vs CMYK and resolution". These are complex discussions with no real solutions but it makes for good reading.

And definitely read the manuals and on-line publications, and do the tutorials. It may put you to sleep but it's the best way to learn...

Report · Mar 01, 2017

I know this is an old post, but it still may be useful information for someone.

Regarding file size, InDesign is notorious for document bloat. Always Save As before exporting. A 100MB InDesign file may turn into a 60MB file, for example.

PDF Optimizer can show you the breakdown of your PDF document. If you go to File > Save As Other > Optimized PDF, the PDF Optimizer popup will appear. On the top right, there is an Audit Space Usage button. If you have a high document overhead, it's likely there's a lot of bloat in the InDesign file. The goal is to get that as low as possible.

It also will give you an idea of how small your file can be. Using InDesign Export methods and PDF Optimizer, I've been able to get a 90MB PDF down to about 5MB.

Report · Oct 17, 2017

MADink Thank you very much for the post. It is most helpful

Report · Feb 18, 2014

hello,

i just sent a poster in jpeg format to be printed but the printer e-mailed to say that the colours of the text was to dark , even th ough it looked fine when i designed it be eithet cmyk or rgb problems?

thank you

Report · Aug 10, 2010

I openly confess to being a beginner (who is seriously trying to learn more) when it comes to color management so I ask you to please be kind.

I am a photographer and I work mainly with stock photo agencies who offer images to photo users. Even though almost of the photo uses are for magazine and book publishers who use offset printers, stock agencies all require RGB files. I recently discovered the "gamut warning" button in PS CS4 and it has changed the way I think about digital photography. When the gamut warning is activated, virtually every photo that I take contains large amounts of out-of-gamut colors, especially in the yellow-green range. If I were over-saturating or over-manipulating my images then I could understand it, but even photos straight out of the camera with no tweaking or correction of any kind have huge areas of unprintable colors. I'm using pretty standard Color Settings in Photoshop.

According to a popular book that deals with Photoshop for photographers, the only way of dealing with this situation is to Select> Color Range> Out of Gamut and then use Hue/Saturation to de-saturate the offending pixels until the gray gamut warning overlay disappears. This is easy to do, but I have to de-saturate the image until the yellows-greens are almost gray. The overall effect on the image is disastrous.

I've found that converting my RGB file to CMYK (using the Relative Colorimetric setting) and then back to RGB produces a much better looking image (only slightly unsaturated, but not objectionably so) but this seems like the wrong way to correct the situation and even though the resulting colors look smooth when viewed on my monitor at 100% I can't help but wonder if some sort of image degradation must occur.

Does anyone have any suggestions or hints? Thanks in advance.

Report · Aug 10, 2010

I would not throw in an extra conversion to CMYK and go back to RGB. A few points to consider:

1. There are many different CMYK color spaces. Some are much larger than others. The gamut warning hinges on your Proof Setup CMYK space – if you are in U.S., this would default to US Web Coated SWOP v2. Just be certain that the CMYK is appropriate for your project (check with your printer).

2. Use Proof Setup. Then you can view the conversion and preserve the source RGB.

3. If possible avoid converting the image in Photoshop. Most document layout programs (such as InDesign) support color management of source RGB images. By preserving source color you can use the same image and repurpose it for a variety of outputs.

4. The color truncation as you move from source RGB to CMYK is quite normal, and it is also normal to see a lot of gray with Gamut Warning. The key is to modify the source image so that the damage moving to CMYK is acceptable. Do not try to eliminate all the grays you see in Gamut Warning. Just make certain that the spirit of the source color is somewhat preserved. Use adjustment layers which are non-destructive. For example, you may see blues shifting to purple. In such case you could add a hue shift layer to move it towards cyan.

5. Many times extremely saturated RGB areas will lose detail on conversion. In such cases the desaturation you mentioned may be warranted, but use an adjustment layer.

6. I recommend Adobe RGB as a source space for print. It is a very large color space. It was designed to contain almost all printable colors. Unfortunately, in order for it to contain almost every conceivable print color, it has fringe colors that extend way beyond print. If your image has these fringe colors, don't try to force them all into your destination CMYK while you are still in RGB. It is normal for the image to take a hit when the move happens, your goal should be making the damage something you can live with.

Report · Aug 11, 2010

Thank you Rick for taking the time to provide this very useful information.

I've made the adjustments that you suggested and I think I'm on the right track now. Especially useful were the suggestions to use Proof Setup and to not try to eliminate all the gray areas in Gamut Warning. I've since learned that the gray areas only show which colors are out of gamut, but without any indication of how much or how little. Proof Setup is a much better indicator of how the final image will look in CMYK.

Thanks again for your help!

Report · Dec 21, 2011

And can I ask a question as I am very new to Adobe Acrobat 9?

So it would appear that you cannot convert an RGB pdf to CMYK in Acrobat 9? You need one of the other programs you are speaking about?

thanks

Report · Dec 21, 2011

Does this help?

http://help.adobe.com/en_US/Acrobat/9.0/Professional/WS58a04a822e3e50102bd615109794195ff-7b94.w.html

Never underestimate the power of the Help files in the Help menu of Acrobat.

Report · Feb 09, 2012