It’s super important for photographers to understand color modes because they can significantly alter the way photographs look, both on screen and in print.
There are two main types of color modes. RGB and CMYK.
RGB stands for Red, Green and Blue. This is an additive color mode. RGB is created with light (like a computer monitor or your phone). You start with Black (no light) and add different amounts of these three colors to make any color imaginable. When added all together you get white.
CMYK stands for Cyan, Magenta, Yellow and Key (Black). This is a subtractive color mode. CMYK is created with ink. You start with white (usually paper) and mix these four colors together in different amounts to produce thousands of different colors. When added all together you get black.
RGB: Anything that’s digital.
CMYK: Anything that’s printed.
Here are some examples:
I’m working on my website and need a new image for my homepage. I’m going to upload the image in RGB since it’s going to be used exclusively online.
I need that same image for a postcard I’m designing for Summer Mini Sessions. I’m going to use that image in CMYK since it’s going to be printed.
RGB is the industry default for DSLRs and computer monitors. It allows us to view colors true-to-life on screen. This is great if your images are only going to be used digitally, but what about if you want to print your photographs?
This usually means you should convert the image to CMYK. If you’re taking your photographs to a commercial printer to have a brochure, postcard, or flyer created, they will most likely ask for your images to already be converted to CMYK.
Commercial printers might be able to automatically convert your image from RGB to CMYK, but the results aren’t always stellar. If you let someone else convert it, you might find the images are darker than you’d like. When you convert it yourself you can have more control over the final results.
Home printers. If you’re printing at home on an inkjet printer, you probably don’t have to convert the image unless you’re having problems with the final result. The technology has come a long way, and most home printers will do a pretty good job of converting automatically.
Print labs. Most of these won’t require you to convert your images from RGB to CMYK. A good print lab is able to do the conversion for you and make sure that everything looks good.
You’ll do this in the same program you use to edit your photographs. In Photoshop you go to Image > Mode> CMYK.
Almost always edit your photos in RGB. When you’re finished you can save out a new flattened file and then convert that image to CMYK. Also try not to convert back and forth (RGB to CMYK and back to RGB). When you convert to CMYK you’re losing some color information because there just aren’t nearly as many colors available (RGB has over 16 million colors vs CMYK having only about 1 million). Once you convert to CMYK you can’t get that data back. I recommend putting CMYK in the file name so you’ll know which ones to use for print.
I recommend always looking at a physical proof. If you’re using a new print lab, send off a range of prints to see the quality before placing a large order (i.e. dark image, light image, colorful image, black & white image). If you’re using a local printer, ask to see a proof of your new brochure before they print the whole thing. It’s much easier to make changes on a proof. Once the whole batch has been printed, it’s usually too late.
If you’re ordering something online and your only option is a PDF proof, you probably won’t have much (if any) control over the final product. This method is generally the cheapest, so a lot of consumers overlook slight variances in color. If you can work with a local vendor, you’ll almost always be happier with the results.