PURPOSE: To generate gravure process picture data without the use of a gravure input device to a line drawing representing characters and ruled lines or the like by providing a data processing means, a data generating means and a data output means in the converter.

CONSTITUTION: When an entry command of multi-value pattern data with a low picture element density is made, a reader 10 receives pattern data via an I/O port 9 and stored the data to a hard disk 8. When an input command of binary line drawing data with a high picture element density is made, line drawing data are fetched from an external recording medium and stored in a hard disk 7. Line number conversion processing is applied to the received line drawing data to convert the data to have the same picture element density as that of the pattern data and to convert the data into multi-value line drawing data. Furthermore, when a conversion command from offset picture data into gravure process picture data is made, the processing of lattice offset picture data into zigzag gravure process picture data is made. The data are outputted to a gravure engraving machine 11.