The process of compensating for the possibility of misregistration (gaps between colors) on the printing press by printing small areas of overlapping color where objects meet is known as trapping.
When a document consists of more than one color of ink the page may have to pass through the printing press two or more times as each color is applied to the paper. Sometimes the paper or the printing plates applying the ink may shift. When objects and colors don't align properly there can be little gaps (misregisteration). Trapping makes those gaps less noticeable, even invisible.
- Choke is the process where a lighter color surrounds and overlaps (traps) a darker color.
- Spread is where a lighter color spreads out and overlaps (traps) a darker color.
Trapping is accomplished with features built-in to some software programs or with dedicated programs devoted solely to trapping. Many commercial printers prefer to do the trapping themselves.
