What are screen colors?

The colors of PC and TV screens are expressed by combining red, green, and blue (RGB).The color of printed materials are expressed by combining four main colors: cyan, magenta, yellow, and black (CMYK).
RGB has a wider range of colors that can be represented than CMYK and is more vivid.

Changes that occur at printing

When a PDF file is printed in color by a printer,
RGB (screen colors) is converted to CMYK (ink colors).
Compare the PDF and the printed paper. Does the paper look duller?

※Exaggerated for clarity. Actual color tones may vary.

What colors cannot be expressed in CMYK?

The more colors are mixed in CMYK, the darker they become. CMYK is mainly used for printing, but not all colors can be expressed in CMYK.
Gold, silver, fluorescent colors, etc. cannot be expressed and are printed using special inks blended called “DIC” or “PANTONE”.

We mainly use DIC for special color printing.