Dot gain is a measure of the difference between the actual ink dot size when printed on a sheet of paper, and the ink dot size specified by the source file. Dot gain happens the print dots appear larger on the sheet due to either mechanical reasons or an optical effect.
Dot gain is neither good or bad, but is a normal result of the printing process. Dot gain should be considered during the creation of the source file, the choice of papers, printing process, inks, etc. If dot gain is ignored, the result can be a printed image that looks darker than intended.
