How Converting Images from RGB to CMYK Affects Color

It’s universally acknowledged that accurately capturing the colors of original artwork is a top priority for most artists. Artists, being naturally inclined towards hands-on approaches, often delve into do-it-yourself methods for color correction. Yet these endeavors frequently culminate in hours spent meticulously adjusting images, only to be met with frustration and disappointment upon seeing the final printed results.

If only achieving precise color representation was as effortless as clicking on the “convert to CMYK” option in programs like Adobe Photoshop. Alas, the reality is far more complex than a simple mouse gesture. The transition from RGB to CMYK often leads to a loss of vibrancy and depth in images, with certain colors bearing the brunt of this conversion more than others.

Understanding how converting rgb images to CMYK affects the color in print for artists

Understanding the Lingo

Before we can tackle the challenges of color-matching photos to match the original artwork, we must first ensure that we are speaking the same language.

DPI or PPI — dots or pixels

Dots per inch (dpi) is a measurement primarily utilized for reproducing photos in print, whereas pixels per inch (ppi) is a term commonly employed in the digital realm. Both terms refer to the resolution of an image. Typically, images on the internet are displayed at 72 ppi, whereas those intended for color printing require a minimum resolution of 300 dpi. However, it’s increasingly common for these terms to be used interchangeably, blurring the distinction between them.

image showing the difference between 10, 72, and 300 dpi

RGB — illuminating colors

RGB represents the trio of primary colors – red, green, and blue – which form the basis of light in TVs, screens, monitors, and digital displays. The amalgamation of these three primary hues yields white, a phenomenon diverging from our conventional understanding of color. Consequently, many individuals encounter challenges when attempting to adjust the colors of an RGB image. Notably, the mixed hues of cyan, magenta, and yellow appear lighter in comparison to the CMYK model.

Note the mixed hues cyan, magenta, and yellow are lighter in value than the CMYK example below.

Red, Green, and Blue light colors mix to create yellow, red, cyan, and white

CMYK — inky depths of printing

CMYK denotes the quartet of primary colors – cyan, magenta, yellow, and black – of ink employed in traditional printing processes. Observe how the amalgamation of cyan, magenta, and yellow produces black, a characteristic unique to the printing realm. For artists, this color model holds familiarity and precedence. 

Note how the combined blue, red, and green hues appear darker in value compared to their RGB counterparts.

Cyan, Magenta, Yellow, and Black ink colors mix to create red, green, violet/blue, and rich black

Examining the printed dots of CMYK inks offers insight into the creation of color images in print media. Notably, the dots visually merge, coalescing to form vibrant color compositions.

Graphic displaying how a 4-color image is printed with CMYK dots. Image curtesy of BenSimonds.com – Halftone Shader
Image courtesy of BenSimonds.com – Halftone Shader

A trick of the trade — A noteworthy technique in the printing industry involves augmenting black (K) ink with magenta or a combination of cyan and magenta dots. This practice, exemplified in the upper left corner of each color plate, contributes to the creation of a profound and opulent color palette. Revisiting the composite image, one can appreciate the dynamic interplay of cyan, magenta, and black inks, resulting in a visually compelling full-color representation.

6 Steps Toward Better Color

1. RGB is not CMYK

It may not be well-known among artists that achieving perfect color on a computer monitor (RGB) doesn’t necessarily translate to accurate color in print (CMYK). This discrepancy stems from the fundamental difference in the color primaries between the two systems. While the image is displayed in RGB, it’s ultimately printed using CMYK inks.

side by side comparison of RGB and cmyk images as viewed on computer monitor. Image curtesy of SmartLevels.com – Technical Help
Image courtesy of SmartLevels.com – Technical Help

Take a moment to compare the RGB and CMYK graphics above. Notice how the mixed hues in each exhibit variations in value from their respective primary colors. These variations illustrate the principles of additive and subtractive color properties, underscoring the complexity of converting between RGB and CMYK.

Several other variables further complicate the task of matching colors to original artwork. Understanding the intricacies of equipment, recognizing disparities between screen displays and printed outputs, and grappling with the challenge of reproducing certain colors accurately in CMYK print—such as purples—are just a few examples.

Did you know that giclée fine art prints utilize high-end inkjet printers equipped with 8–12 different archival inks? These include Photo Black, Cyan, Vivid Magenta, Yellow, Light Cyan, Vivid Light Magenta, Light Black, Matte Black, Light Light Black, Orange, Green, and Violet. This extensive ink palette not only enhances color accuracy but also contributes to the higher cost associated with giclée prints.

2. Apples and Oranges

It’s an established truth in the digital realm that not all screens—be they monitors, laptops, or tablets—are created equal. Variations in manufacturing, settings, and age contribute to subtle yet discernible differences in how images are displayed across different devices. Moreover, even a single screen can undergo shifts in color accuracy over time, influenced by factors like usage frequency.

What might come as a surprise is the meticulous approach employed by industry professionals to counteract these challenges. These experts calibrate their screen displays and output devices using specialized equipment regularly, sometimes as frequently as weekly. This practice ensures consistent and accurate color reproduction, safeguarding against the unpredictable nuances of digital displays.

3. Give Yourself a Hand — a color hand

For those who are deeply committed to achieving precise color accuracy, incorporating a Color Calibration Chart into your workflow can make a world of difference. By including this chart alongside high-resolution photographs and scans of your artwork, you provide printers with a vital reference point for adjusting images accurately before they go to print.

Color calibration chart with color recipes listed, is an essential tool for artists
Color calibration chart, front and back, with the color recipes.

The chart features squares of color, including those printed with 100% Cyan, Magenta, and Yellow inks, as well as a gradient from pure white to 100% black. In the era of digital photography, this comprehensive value range serves as a valuable tool for fine-tuning white balance and ensuring color fidelity.

To delve deeper into the functionalities and benefits of the Color Calibration Chart, consider exploring the article Meet Your New Friend—the Color Calibration Chart for further insights. Color calibration charts come in a range of options and prices. Here’s an affordable yet effective solution available on Amazon.

4. Pixels Matter

Begin with the highest-quality, most detailed photo or scan available. Remember, you can always reduce the resolution or DPI/PPI to suit specific requirements, such as web display, but you can never enhance it beyond its original quality.

Picture each pixel as a tiny square of color, working together to form a faithful reproduction of your artwork. When you boost the numerical DPI/PPI of an image in software like Photoshop, you’re essentially dividing each color square into smaller segments. However, these newly created segments will still retain the appearance of the original square. This is because simply increasing resolution doesn’t add more detail to the image; it merely results in a printed image that appears pixelated.

A crucial point to remember: never upscale a 72 DPI image to 300 DPI for printing purposes. While it’s a common guideline that web images are typically 72 DPI and print images should be at least 300 DPI, forcing a low-resolution image into a higher DPI setting will only yield unsatisfactory results.

As a best practice, always provide printers with the highest resolution file available and allow them to adjust the resolution according to their optimal output requirements. This ensures the best possible reproduction quality for your artwork. Read more about photo resolution in the article Answering the High/Low Res Question.

5. Don’t Size UP

I emphasized the significance of DPI or PPI in image resolution; enlarging or scaling up an image can severely compromise the quality of the printed picture. Consider this scenario: when you enlarge or scale up an image for print, you’re essentially magnifying the pixels or color squares, which often results in a noticeable loss of detail and sharpness.

A crucial point to remember is to refrain from enlarging an image for print purposes. Doing so only exacerbates the issue by further stretching the existing pixels, degrading the visual outcome.

There is, however, a scenario where enlarging an image can yield satisfactory results—provided you start with a significantly higher resolution, such as 1600 DPI. This underscores the importance of capturing photos of your artwork at the highest resolution feasible, ensuring that you have ample detail to work with during the printing process.

6. Make a Sacrifice

During my tenure in advertising, we often pondered over a trilemma: Quality, Time, or Cost—choose two. While it might sound like a sacrifice, it’s more about prioritizing what matters most in a given situation.

These priorities are fluid and subject to change depending on each printing project’s requirements. For example, when printing 200 postcards, the emphasis might be on time and cost efficiency. Conversely, when producing 50 giclée prints, quality emerges as the paramount concern.

Understanding which facets to prioritize ensures that each printing endeavor is tailored to effectively meet its specific objectives and constraints. So, when embarking on a new project, consider which combination of Quality, Time, or Cost will best align with your goals and requirements.

Going Forward

Now that you know some of the factors involved in getting a good color representation of your artwork in print, let’s use that knowledge.

Quick and Inexpensive

  • Online printing services like Vista Print or Overnight Prints are a great option for getting your printing needs taken care of quickly and inexpensively. However, it is important to keep in mind that the final printed materials may not have perfect color accuracy. Despite this, there is nothing inherently wrong with using these services. In fact, I have personally used them for printing business cards, postcards, and other materials. While I know that I may be sacrificing some color accuracy for the sake of cost and speed, I still find these services to be a valuable resource.
  • It is recommended that you check a digital proof for placement and accuracy, but the colors may not be accurate to the final printing.

High Quality

  • To ensure the best quality, working with a professional printer with the expertise and experience to deliver superior results is recommended.
  • Professional printers employ color experts who work in a specialized environment with color-balanced lighting to ensure the best color match in printing.
  • In addition to the high-resolution photograph or scan, it’s important to also include the RAW digital photo file. The RAW file contains minimally processed data from the camera or other sources.      
  • Provide the original artwork for the printer to match the color. I realize that this may not always be an option. Including the color calibration chart with your art in the original high-resolution photograph or scan will also help printers do their best color matching.

Whew! Who knew there were so many factors to consider?

Honestly, though, this barely scratches the surface of what’s involved in getting the best color reproduction of your original artwork; there is dot gain, file types, image compression, paper surfaces, and so on. No wonder you’ve ended up frustrated after spending all that time at the computer adjusting colors, and why it’s not as easy as selecting “convert to CMYK” in Photoshop.

Thanks for reading, hope you found this helpful!

nancy

I understand that you may be curious about my background and how I gained my knowledge of color and printing. I acquired a strong foundation in these principles while attending college and further honed my skills during my time in the advertising industry. As a result, I have hands-on experience in preparing files for print and maintaining rigorous quality standards. Furthermore, I have gained extensive experience in managing print projects from start to finish by working directly with printers throughout the years.


Other Helpful Resources:

Get the Best Images of Your Artwork
Answering the High/Low Res Question
Quick Steps to Photograph Your Art with a Cellphone — if it’s your only option!

Meet Your New Friend — the Color Calibration Chart
– Color Calibration Chart on Amazon

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6 Comments

  1. So well written, Nancy. Now I understand why a good photographer and printer are so worth what they charge. Thanks, great information!

    1. Nancy Murty says:

      Thank you Mickey. 🙂

  2. You put a lot of effort into this article. Thank you so much!

  3. Stefani Tadio says:

    Wow, did I learn a lot! Thanks Nancy – this was brilliant!

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