CMYK Rounding for Perfect Colors

When we are preparing a file for commercial printing, at the most basic level, our objects either receive a Process color (CMYK) or are assigned a Spot color. The subject of choosing the right color is related to many factors; alongside these factors, professional experience, file scrutiny during imposition, and observing the results of various past jobs definitely play an influential role.

Nevertheless, we must begin this process somewhere so that as we progress, we evolve into a designer who, in addition to mastering prepress aspects, also possesses the ability to understand, examine the file, and hold the appropriate decision-making power at that moment, based on the prevailing printing conditions.

We will temporarily set aside other subjects to be addressed in later sections, such as: whether the selected object is meant to receive a Fill or a Stroke color, what its dimensions are, or if it is intended to cover a vast colored area or merely a 0.5-point stroke line.

A designer's knowledge of how to properly apply the right color code to different parts of the file will not only have a significant impact on the final print quality but, by recognizing disruptive factors, can also lead to the file being printed with greater precision. Furthermore, it helps the printing operator to focus their primary attention on crucial elements during the press run to deliver a standard job.

Color Selection Methods

1- Standard Color Books: You can proceed with selecting the appropriate color code by utilizing standard color swatch books from various companies, most notably Pantone, which is the most reputable, and by studying the guidelines mentioned at the beginning of the book. Given the price of these color books and their different categories (such as Coated/Uncoated/Metallic), readily accessing them everywhere is often not feasible.

2- Professional Experience: Undoubtedly, after gaining experience over time, examining print results, and incorporating the knowledge of others, you will develop a substantial database of information regarding various colors. For instance, you might learn through experience that one of the recommended codes for achieving a pleasant-looking orange on glossy paper is (C:0 | M:60 | Y:100 | K:0). It is also possible that a certain color code is so commonly used that most operators and print supervisors are aware of it and recommend you use it. You can even save these codes as a personal color palette in Adobe Illustrator.

3- Utilizing the Color Picker: Initially and at first glance, we won't have a specific understanding of CMYK, because as mentioned before, this color mode is a dependent state and the language of the printing press. However, a factor that often remains hidden is the HSB mode, which, upon explanation, you will fully realize is completely understandable to the human mind and possesses a common language worldwide.

HUE: This is the color spectrum understandable to the human eye, which was also discussed in previous articles. Therefore, we first determine which range our selected color belongs to, such as blue, green, red, or purple.
SATURATION: This expresses the quality and intensity of the color. Imagine you have selected a red color; in its default state, the red is displayed naturally and at its highest quality. However, by reducing the saturation, the amount of white becomes more apparent, and the strength of your original color is diminished.
BRIGHTNESS: Consider that same red color being viewed in a room with natural lighting. Now, what would you observe if the level of brightness were reduced? The red color itself hasn't changed, but the decrease in light has caused you to perceive a darker red.

CMYK Rounding

Therefore, in the first step, you choose the desired color through the Color Picker window or the Color panel and define the three aforementioned indices according to your mental preference. Next, we must set the appropriate color code for printing. Now, to adjust the color codes, we examine the value of each channel in CMYK. This number should be set to a multiple of five, meaning the channel under review is located between two numbers for rounding.

The C, M, and K channels are considered dark colors due to their density and the nature of the ink, and they become slightly darker in print. Therefore, they are rounded down to the lower number. For instance, after selecting a color, we go to the Cyan channel and notice its value is 68. This value is clearly between 65<68<70; thus, it is set to 65.

The Y (Yellow) channel will have a different adjustment because its color nature is weak and it has very high brightness. Imagine printing yellow on white paper; you'll notice it doesn't appear like other colors, and its primary function is to brighten and enhance other colors. For this reason, it will be rounded up to the higher number. In some cases, if no significant difference is made, we even upgrade its value by two steps higher (to the next multiple of five).

With these steps, you can apply an appropriate color to your objects at the beginning of your journey. However, this is not the whole story. Factors such as color management, imposition planning, and professional experience are what allow you to operate more expertly. For instance, how should you optimize a navy blue color so that it prints attractively, and which channel should the ink be transferred from to another? Or, as shown in the image above, the Black channel has been reduced to zero! So, how should I control the darkness? Perhaps it is necessary for the Black channel to be set to 5% while reducing the Yellow amount, or even bringing it down to zero.

Why 5%?

But let's address this question: Why should the values be set to a multiple of five? Have you ever paid attention to the default color codes in the CMYK color palette within Adobe Illustrator? The fact that all codes are multiples of five traces back to the Slug area during imposition by the prepress facility. This area contains elements used to control various factors during the print run and includes vital control elements for print supervisors.
The operator cannot adjust the entire job solely by relying on their eyes when checking colors. Instead, they use specialized tools to check the color bars (or color steps) placed around the form. These steps are arranged as boxes in multiples of five or ten around the form, and they manage part of the color control process. In this manner, all the colors in your file will be examined by referencing the color control strip.

Conclusion

In a general summary, we link the rounding of colors in the software to the plate form in prepress and printing. Colors are rounded because the indices on the color bars used during printing by the operator or the quality control supervisor are also rounded. This creates harmony from the moment the color is defined until it is reproduced on the press. However, colors are not always treated this way; in complex object-based illustrations, it is not always feasible to adjust every single color. For this reason, color correction using multiples of five is usually confined to brand identity elements, logos, and background colors.