Definition:
In order to compensate for minor misalignments on the printing press it is sometimes necessary to slightly overlap touching colors to camouflage any gaps that might occur. Choke and spread are similar terms used to describe the process of intentionally overlapping touching colors or trapping.
With a choke a lighter color surrounds and overlaps (traps) a darker color.
Applying a choke can be done manually or automatically in some desktop publishing software; however, some commercial printers prefer to handle the trapping themselves so before you choke or spread your files, check with your service provider.
Examples:
When a dark color box is inside — surrounded by a light color box, the lighter color box will overlap or choke the darker color to prevent an obvious gap if the images get slightly out of alignment. By contrast, if the dark color box is surrounding the light color box, the lighter color will overlap or spread over the darker color.
