Four-color process
Full-color printing made by layering halftone dots of cyan, magenta, yellow, and black ink instead of mixing a separate ink for every color.
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What it is
Four-color process builds a full-color image from cyan, magenta, yellow, and black ink. The artwork is separated into four halftone plates, and their tiny dots overlap on paper so the eye reads many more colors than the four inks in the press units. Put a printer's loupe on any magazine page and those four screens resolve into a rosette.
It is the standard route for photographs, illustrations, magazines, packaging, and other work with broad color variety. Use a spot ink as an extra plate when a brand color, fluorescent, metallic, or other special ink cannot be reproduced closely enough with CMYK.
Gotcha: a monitor's RGB color does not have a fixed CMYK recipe. The conversion changes with the ICC profile, paper, and press condition, and heavy shadows still have to stay under the job's TAC limit. Keep the tagged RGB master and convert a production copy once.
Ask AI for it
Prepare this artwork as a four-color process job. Keep the tagged RGB master untouched, convert a production copy with Adobe Photoshop's Convert to Profile command using PSO Coated v3 (FOGRA51), preserve small black type as 0C 0M 0Y 100K, and remove unintended spot plates in Adobe Acrobat Pro Ink Manager. Export PDF/X-4 and verify the C, M, Y, and K separations individually in Output Preview.