RGB - digital printing

Ask a Smartpress.com Expert: Converting RGB to CMYK

Ask a Smartpress.com Expert: Converting RGB to CMYK

I didn’t realize I made my design file in RGB, I think my digital printing results will be better with the CMYK color model. When I converted it, the colors didn’t look right. How can I fix the colors in my graphic design file when converting it from RGB to CMYK?

– Enraged by RGB

Smartpress tutorial - RGB image

RGB Original File

I feel for you. Anyone who has ever converted an RGB image to CMYK knows how frustrating results can be. The beautiful image you worked so hard on is a shadow of what it used to be – literally, because the most notable difference is going to be reduced color saturation.

Smartpress tutorial - RGB to CMKY

CMYK Converted File

One great thing about working with Smartpress.com is we have the capabilities to print from RGB files. We can create a hard copy proof for you based off of your RGB image and you can take a look at it to see if it appears the way  you want it. If it does, you don’t need to do the work to go through the conversion process.

If it doesn’t look quite right, you can convert the file to CMYK, but you may lose some of the detail and the contrast in your image. The problem with such a conversion is that the range of colors, referred to as gamut, produced using CMYK color inks on paper is different than what can be represented using RGB. This where the changed color hues and a dull appearance originate. Thankfully, there are ways to restore the colors that are lost in your RGB to CMYK conversion.

First, some instructions on converting your images from RGB to CMYK in Photoshop.

  1. Make any adjustments or edits to your image, including applying filters, while the image is still in the RGB color space. Save and close the file.
  2. Select “Edit” then “Color Setting.”
  3. At the dropdown list under “Settings” you will see presets for Europe, North America and Japan. Select the appropriate location.
  4. Next, select a CMYK profile that best suits the final printing conditions. For example, “U.S. Web Coated (SWOP) v2” is our default color management profile at Smartpress.com.
  5. Clicking on the “More Options” lets you set the rendering intent to use when converting from RGB values to CMYK. Our default here at Smartpress.com is “Relative Colorimetric,” which offers results more faithful to the original color and commonly used for digital printing applications.
  6. Once you have the best color settings, you can open the RGB image you want to convert.
  7. A photograph from a digital camera will probably have an embedded RGB color profile. If Photoshop presents a window with “Embedded Profile Mismatch” then select “Use the embedded profile.” If Photoshop presents a message that says the image does not have an embedded RGB profile, choosing to “Assign profile” to Adobe 1998 is a good option.

    RGM CMYK Gamut Warning

    The Gamut Warning will show in gray which colors won’t convert cleanly.

  8. To see which areas of the image that are “Out of gamut”, select “View” and then “Gamut Warning.” Any colors that turn grey are colors that can not be produced in the CMYK color space and Photoshop will have to select the nearest color to it, depending on the rendering intent you selected earlier.
  9. To covert from RGB to CMYK, select “Image,” then “Mode,” then “CMYK Color.”

Once you’ve made the conversion, you will probably notice that some of the colors changed and have almost a faded look. Here is one way to try to restore the color, though there may be other methods that might work better with your particular image:

  1. Add a new layer in Photoshop.
  2. Fill it with black.
  3. Set the color mode of the layer to Color Burn.
  4. Adjust the layer opacity until you’re happy, usually in the 15-35% range.
  5. You can also add a Hue/Saturation adjustment layer. Find a balance between the saturation adjustment layer and the color burn layer to get your CMYK conversion as close to the RGB original as possible.

Ideally, your best bet is to create the images for your digital printing project in the CMYK space in the first place because RGB suffers a loss of color when it is converted. You can use the above to get as close as possible to appearance you’d like your image to have.

Have a question about online printing that you would like to have answered? Leave your question in the comments below or email us at customerservice@smartpress.com and we will do our best to answer your questions.

About Jill Alfano

Jill Alfano, mother of two, loves musicals and gardening. She has 12 years of prepress and printing experience in digital, offset, flexo and screen printing.