What is 4-color process printing (full-color printing)?

Full-color printing uses four ink colors — Cyan (C),Magenta (M),Yellow (Y),and Black (K) — also called CMYK. By layering and mixing these four inks in different percentages, a wide range of printable colors can be reproduced.

This method is used for both offset printing and digital printing.

Full Colour Printing - CMYK 01 Image

About Color Reproduction

Because CMYK printing relies on mixing ink on paper, some color variation is unavoidable.

This means colors may vary slightly between:

  • one print run and another
  • different machines
  • different paper types

Offset presses generally offer more consistent color than digital presses, but even then, small variations are normal in CMYK printing.

What do 4c/4c, 4c/1c, and 4c/0c mean?

These terms indicate how many colors are printed on each side of the sheet.

Front
Back

4c / 4c

CMYK full color

CMYK full color

Full Colour Printing - CMYK 02 Image
Full Colour Printing - CMYK 03 Image

This means both sides are printed using all four CMYK inks.

Front
Back

4c / 0c

CMYK full color

No printing

Full Colour Printing - CMYK 02 Image

Only the front side is printed.

Important

Important: About Grayscale Images If you want the back or front to print in true grayscale (black ink only):
You must convert the image to Grayscale mode in Photoshop first.


Even if the image looks black-and-white on screen:

  • If it is still in RGB or CMYK mode, Illustrator will treat it as a color image, which causes the press to use multiple inks (CMY+K) to reproduce gray.

This can result in:

  • unexpected color shifts (bluish-gray, reddish-gray, etc.)
  • inconsistent tone
  • printing with multiple plates instead of one

✔ Correct procedure

Before placing the image in Illustrator or InDesign:

  • Open the image in Photoshop
  • Convert it to Image → Mode → Grayscale
  • Save and place into your layout

This ensures the gray prints using only black ink, as intended.