JPH0332949B

PURPOSE:To obtain accurate picture data regardless of the fluctuation of the effective light emitting quantity of a light source itself, by using a value obtained by dividing the data obtained from a photosensor by the direct effective light emitting quantity of the light source as the picture data. CONSTITUTION:An original table 11 is shifted in a fixed direction by a subscan motor 12 which is revolved intermittently. While three light source lamps 6R, 6G and 6B are set on the back side of the table 11 in response to three colors R, G and B respectively. The signal C fed from a control photosensor 8 is stored once to a capacitor 41 in a light quantity circuit 40, then supplied to a sampling holder 43 by a sampling signal PS supplied from a timing signal generating circuit 15 via a switch 42. The holder 43 holds the input value until the next sampling signal PS is supplied, and at the same time supplies the signals, i.e., the correction signals C (CR, CG and CB) to a light quantity correction divider 21 synchronously with signals R, G and B. Then the divider 21 supplies the values obtained by dividing signals R, G and B by their correction signals CR, CG and CB respectively to an A/D conversion preprocessing circuit 19 as the picture data of R, G and B.