A quick, plain-English guide to color modes, halftones, and how to get your files print-ready — straight from our production team.
Cyan, Magenta, Yellow & Black — the four inks behind every printed page.
Send it our way and we'll check it before it ever hits the press — no surprises, no color shifts.
Ask Our TeamCMYK identifies the four colors used in traditional printing presses, and stands for, respectively, cyan, magenta, yellow, and black.
RGB refers to the so-called scientific hues — the additive primary colors red, green, and blue — that, when mixed together in equal amounts, create white light. Television sets and computer monitors display their pixels based on values of red, green, and blue.
While the more common decimal system uses a base of ten to represent all possible numbers, hexadecimal notation uses a base of sixteen: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, A, B, C, D, E, F. While such a system may seem confusing at first, it works extremely well in computing environments. For example, a single byte of information can be represented as eight bits (10011101), decimal numerals (913), or simplified to hex (9D). In hex, every byte can be shown as two hexadecimal characters.
As it relates to Web design, hexadecimal is the alphanumeric system used to specify colors in HTML. For example, the hexadecimal equivalent of white is FFFFFF, while black is 000000.
Computer monitors emit color as RGB (red, green, blue) light. Although all colors of the visible spectrum can be produced by merging red, green and blue light, monitors are capable of displaying only a limited gamut (i.e., range) of the visible spectrum.
Whereas monitors emit light, inked paper absorbs or reflects specific wavelengths. Cyan, magenta and yellow pigments serve as filters, subtracting varying degrees of red, green and blue from white light to produce a selective gamut of spectral colors. Like monitors, printing inks also produce a color gamut that is only a subset of the visible spectrum, although the range is not the same for both. Consequently, the same art displayed on a computer monitor may not match that printed in a publication. Also, because printing processes such as offset lithography use CMYK (cyan, magenta, yellow, black) inks, digital art must be created as CMYK color or must be converted from RGB color to enable use.
All work should be in the CMYK (Cyan/Magenta/Yellow/Black) mode, as this is the mode required for the printing process. If an RGB (Red/Green/Blue) file is submitted, it must be converted to CMYK. When the conversion takes place, color shifts can occur and our team will do our best to reproduce as close a match to your printed output as possible.
It can sometimes be difficult to visualize the reason for color shift in color space conversion. The best way to see the color differences between the CMYK and RGB color spaces is to look at a color gamut comparison chart, which plots the visible color spectrum as a large "horse shoe" area, with the CMYK and RGB colors plotted inside it. In some areas the RGB color space falls "outside" that of the CMYK space — it's these colors that will be affected by a conversion from RGB to CMYK.
Most desktop scanners, digital cameras, and video capture systems save files as RGB, and the conversion of RGB files to CMYK can be done in many ways. RGB converts to only CMY directly. However, when printing, we must add black ink and in doing so must cut back on some color. The Undercolor Removal (UCR) setup helps control this ratio so that a maximum ink density for the four colors will be 300% when printing on a coated paper stock.
In offset lithography, the density of CMYK inks can not be varied in continuous fashion across an image, so a range is produced by means of halftoning. In halftoning, translucent CMYK ink dots of variable size are printed in overlapping grids. Grids are placed at different angles for each of the ink colors. Smaller halftone dots absorb less light; thus, as a result of an increase in the amount of reflected light, apparent density is decreased and the object appears lighter.
Here's a list of several common programs with instructions on how to make sure you're working in the CMYK color space. If your program or version isn't listed here, don't worry — most of these instructions will apply to all versions of a program. If at any time you need further help, give us a call. We're happy to talk you through the steps needed to get your document into the CMYK color space.
Publisher defaults to RGB. Go to Tools → Commercial Printing Tools → Color Printing and select Process Colors (CMYK). All images in the layout must be linked, not embedded, to keep their CMYK color space — use Tools → Commercial Printing Tools → Graphics Manager, highlight the embedded image, click Link, then Browse to the original file. Send us both the images and the layout file.
For an existing file: Image → Mode → CMYK Color. When starting a new file, select CMYK Color as the mode before clicking OK.
Select each object you want to convert. Open the Fill tool → Fill Color Dialog and set the Color model to CMYK. For any object with an outline, open the Outline tool → Outline Color Dialog and set the Color model to CMYK there too.
For an existing file: Edit → Select All, then Filter → Colors → Convert to CMYK. For a new file, choose File → New and select CMYK Color for the Color Mode.
Go to Edit → Edit Colors → Show Colors in Use, highlight a color and click Edit. Change the model to CMYK and deselect Spot Color. Remember to send us your layout and linked images.
Open Window → Swatches and Window → Color. Double-click a color in Swatches, change the color mode to CMYK and the type to Process. Any colors created outside the Swatches palette should be converted the same way — select each object and confirm the Color palette reflects CMYK percentages (use the top-right palette arrow to switch to CMYK if needed). Remember to send us your layout and linked images.
Open Window → Show Colors. Double-click "Colors" in the palette and set the Model to CMYK and Type to Process. Note that Pagemaker does not accurately represent CMYK color on screen.
