Abstract: An ink feeding method for a printing machine includes a color density measuring step for measuring color density of prints at intervals of time, a variation coefficient computing step for computing a variation coefficient for varying the ink feeding rate based on the color density of prints and a target color density of prints, a color density gradient computing step for computing, based on the color density of prints, a color density gradient representing a rate of variation in the color density of prints occurring with an increase in the number of prints, an expected color density computing step for computing, based on the color density gradient, an expected color density of prints occurring after a predetermined number of prints are made, a determining step for determining whether the expected color density of prints occurring after the predetermined number of prints are made exceeds the target color density of prints, and a variation coefficient correcting step for correcting the variation coefficient whe

Abstract: A printing apparatus includes an image reader for reading an image on a printed paper sheet to obtain image data, and a controller for controlling the image reader to obtain image data about a color chart including solid patches once for every predetermined number of printed sheets or at every predetermined time interval which is inputted and set. The controller processes the image data to compute a printed density of each solid patch. Measurement data including the printed density are sequentially stored in a storage section in association with the number of printed sheets or time. The measurement data stored in the storage section may be displayed by a display section or outputted to a print section in the form of history data indicating measurement data transitions. Thus, the printing apparatus including a device for measuring printed sheets can perform history management on the measurement data for every predetermined number of printed sheets or at every predetermined time interval.

Abstract: An image scanning technique of the present invention shortens the time required for reading images of a plurality of originals set on an original tray. The positions of a lens 18 and a line of CCDs 20 are adjusted, so as to enable a scanning range of the line of CCDs 20 in a primary scanning direction to cover a plurality of originals. A first shooting range Z1 of the line of CCDs 20 covers four trimming areas Tr1,Tr2, Tr5, and Tr6. The procedure of the image scanning technique first reads white reference data of a white reference plate in the first shooting range Z1, then scans the four trimming areas Tr1, Tr2, Tr5, and Tr6 while fixing the shooting range to the first shooting range Z1, and carries out shading correction to correct image data obtained by the scan with the white reference data. This structure requires the process of scanning the white reference plate and updating the white reference data only once for correcting the image data of the plurality of originals.

Abstract: An image scanning technique of the present invention shortens the time required for reading images of a plurality of originals set on an original tray. The positions of a lens 18 and a line of CCDs 20 are adjusted, so as to enable a scanning range of the line of CCDs 20 in a primary scanning direction to cover a plurality of originals. A first shooting range Z1 of the line of CCDs 20 covers four trimming areas Tr1, Tr2, Tr5, and Tr6. The procedure of the image scanning technique first reads white reference data of a white reference plate in the first shooting range Z1, then scans the four trimming areas Tr1, Tr2, Tr5, and Tr6 while fixing the shooting range to the first shooting range Z1, and carries out shading correction to correct image data obtained by the scan with the white reference data. This structure requires the process of scanning the white reference plate and updating the white reference data only once for correcting the image data of the plurality of originals.