If you want to understand exactly why your RGB files will have to be converted to CMYK before they can be printed, visit our RGB and CMYK advanced color guide.
Now comes the how, which can be more complex than you’d think. Here’s some information on how color conversion works and how to avoid common pitfalls.
The simplest method is just to submit your RGB files and let us convert them for you. We’ll show you the CMYK files in your Electronic Proof before going to press, so you’ll be able to see exactly how your colors have changed in the conversion process.
However, this method provides the least amount of control for you, since we won’t make any changes to your colors beyond the conversion. If you want to be able to tweak your colors after conversion, you should convert them on your end before uploading your artwork.
If you want the most possible control over your colors, we recommend you convert colors on your end.
This can be done in both InDesign and Photoshop.
Note: we do not recommend using Adobe Acrobat Pro to convert your colors, unless you have professional pre-press software like PitStop installed. Acrobat’s built-in color conversion engine provides very sub-optimal results.
1. Start by selecting Edit -> Convert To Profile.
Once you click ‘Convert to Profile’, you will get the following dialog box:
Let’s take a second to examine each of these options and why we’ve chosen the ones above.
2. Source Space: This will be set based on the current color profile of the files you’re working on.
3. Destination Space: Since you’re converting to CMYK, the important setting here is ‘CMYK Profile’. For submitting files to PrintNinja, you should choose “Japan Color 2001 Coated”, since that’s the specification used by most printing companies in China.
4. Conversion Options: Adobe (ACE) is your best bet for conversion engine, and in most cases, you’ll want to choose ‘Relative Colorimetric’ for your Intent. This option will preserve all RGB colors that can be reproduced accurately in CMYK, and it will replace any colors that cannot be reproduced accurately in CMYK (known as ‘out of gamut’ colors) with their nearest CMYK match.
5. Click ‘OK’
Your document is now in CMYK! Take a look at how your colors have shifted. If you had any very bright blues, reds, and greens, chances are they’ve been reined in to account for CMYK’s reduced color gamut.
Many creators who work primarily in digital media are very disappointed at the way this conversion dulls their colors, but as we talked about in our Advanced RGB vs. CMYK guide, the hard truth is that there is physically no way to reproduce many RGB colors on the printed page.
However, because you chose to convert colors yourself, you now have some options to play with your CMYK colors.
In terms of global changes, if you’re working in Photoshop, you can try playing with levels, contrast, and saturation.
However, the most thorough way to improve your colors is go to through and alter the CMYK values of the colors themselves. Use your color selection / eyedropper tool and take a look at how much of each color of ink you’re using.
Then, use a guide like PrintNinja’s suggested CMYK values guide to help familiarize yourself with common CMYK combinations that make colors that really pop, and what combinations to avoid.
Once you’ve made any tweaks and adjusted your colors to where you’d like them, you’re now ready to export to PDF!
Generally, the “Press Quality” default settings in InDesign and Photoshop are great, however for submitting files to PrintNinja, we recommend that you do not do any further color conversion or embed any color profile information.
In order to keep this from happening, you’ll want to use the following settings in the ‘Output’ pane of the PDF export dialog (InDesign is on the left and Photoshop is on the right):
And there you have it! A completely CMYK PDF file ready for submission to PrintNinja for printing.