The Colors Look Dull and Muddy

Have you sent a nice digital image of your artwork to the printer for a show and the postcard came back with dull, muddy looking colors? It happens all the time, and in this article I'll explain why.

RGB In
Since the late 1920’s, scientists have developed a variety of mathematical formulas – or models – for defining the individual colors we can see.

Computer screens, digital cameras, and scanners use an "RGB" color model, which combines Red, Green, and Blue light in varying proportions to produce other colors. This is an "additive" model because equal amounts of red, green, and blue light added together produce white.

Commercial printing uses a different model, "CMY", to produce the color in printed images using Cyan, Magenta, and Yellow inks. This is a "subtractive" model because ink absorbs light that would otherwise be reflected off the paper. An equal amount of the three inks eliminates all reflected color and produces black.

In practice, though, black ink also is added to provide the detail in a printed image and to produce neutral grey tones and a true black. The combination often is referred to as "CMYK", process color, or 4-color printing.

... Garbage Out
The color of a pixel in an RGB image is determined by three numbers, or values, representing the intensities of red, green, and blue light. The same color in a CMYK image is represented by values for the amounts of cyan, magenta, and yellow ink. Because the RGB and CMY models define colors differently, these values are not interchangeable.

And this is where the trouble starts. An RGB image must be converted to CMYK in order for the colors to be reproduced accurately. Printing from an unconverted RGB file will produce a printed image with dull colors that are somewhat muddy looking and darker than the original.

Nearly all of the images commercial printers receive are already CMYK and can be printed directly. If you don't tell the printer the image is RGB and ask about conversion, they are likely to assume it is a CMYK file. And when the postcard you get has dull, muddy colors, it probably means your RGB image was used without first converting it to CMYK ... Oops.

Ask And Tell
Converting images to CMYK requires some skill and knowledge of printing processes. Many commercial printers will make the conversion for free or at a nominal charge. If you're using a professional photographer or a graphic designer, ask them about converting the image to CMYK. Or try the conversion yourself if you are comfortable using Photoshop® and know what printing process is going to be used.

So, the problem is an easy one to avoid. Ask about conversion to CMYK and tell the printer if you're sending an RGB image. Otherwise, don't expect to be satisfied with the colors on the postcard.

And click here to learn more about color models in the Learning Center at ShootMyArt.com™.