I created an InDesign document (4 pages) that has various shapes that are different colors (yellow, green, etc.). The shapes are InDesign shapes (not imported graphics). We originally created the document to be exported as a PDF and shared online. The green shape color we used (a neon green) looks fine in RGB. However, when we try to export the document to CMYK (we decided that we need to be able to print the document on a CMYK printer also) the neon green color turns into a dark, forest green color. I'm pretty new to InDesign and I'm not sure how to replicate the neon RGB green to look the same in CMYK. Any help would be appreciated! Thanks.
It's a known problem but there's is a way to control it and minimize the damages:
- Select your RGB color from the colors list and press "new color":
- Double click on your new color, inside the new color change the mode to RGB, make sure you don't have the error message and control the RGB handlers until you get to the desired color:
- Now you have 2 options, either replace the colors in the find and replace window (both objects and characters) or delete the old RGB color, and when you do that Indesign will ask you with what to replace it, and choose your new CMYK color. I recommend doing the last option, that way you have no doubt you changed each and every single place where the old color was.
This happens do to the fact that RBG color space is an additive process of light. CMYK can't produce neon colors because it's ink. It's a subtractive color space meaning the less ink, the brighter the color. The way you get neon green is using a custom spot color ink. The most common spot color library is Pantone. If you show a print shop your RGB color they can convert it for you to a spot color using the Pantone matching system. I hope this helps clear things up.
In short, CMYK is for printer inks which can replicate a certain amount of colours. RGB is mainly digital and can reproduce many thousands of colours.
You're neon green colour may just not be able to be made when mixing inks, so maybe using indesign and Naty's method of using CMYK colours, it could help to find a close match rather than find the EXACT colour.
Eddie's answer about Spot Colours is useful, but most printers would charge extra for spot colours as they would need to create a new plate just for that specific colour, if you have 3 or more of these spot colours, your printer will be cursing your name
If you can get away with a closest match that doesnt hurt your design, id say go for that. if not, spot colour could be a possible route but definitely check with you/your clients printer first.