PURPOSE: To obtain printed matter of stable quality by obtaining an approximation formula for the representation of a relationship between a printing rate and a dot gain value, and calculating a printing rate for the obtaining of a desired dot gain value based on the approximation formula to perform a printing.
CONSTITUTION: A pedestal is allowed to run at a speed V by rotating a motor 22 with a drive unit 66 to measure a dot gain value Da on a printed matter using a densitometer 72. Following this procedure, the motor 22 is caused to rotate at high speed to run the pedestal at a speed Vb for the measurement of a dot gain value Db. Next an approximation formula for the representation of a relationship between printing rates Va, Vb and dot gain values Da, Db is formulated by an arithmetic part 58 based on function data written into ROM 44, When a desired dot gain value Dn is entered by a keyboard 70, and a printing rate Vn is calculated by the arithmetic unit 58 on the basis of the earlier obtained approximation formula, outputting the printing rate to the drive unit 66 for printing.
AWAZU YASUNOBU
ONOKI SHIGEO
