Image forming apparatus, image forming method, and storage medium

Abstract

An image forming apparatus includes a printing unit configured to print a chart in which patterns, each including an image object in a first process color and an image object in a second process color, are arranged at each of at least three positions in a main scanning direction, a receiving unit configured to receive, from a user, a plurality of pieces of information relating to correction of a color shift between the first process color and the second process color, the plurality of pieces of information being based on the patterns arranged in the printed chart and each corresponding to a different one of the at least three positions, and a correction unit configured to correct the color shift between the first process color and the second process color based on the received plurality of information.

What is claimed is: 
     
         1 . An image forming apparatus, comprising:
 a storage device configured to store image data;   a controller configured to read the image data out of the storage device on a basis of correction information for correcting a print position shift in a sub scanning direction of an image of a first color and an image of a second color;   a printing unit configured to print the image of the first color and the image of the second color on a sheet on a basis of the image data read by the controller; and   a user interface configured to receive information from a user,   wherein the storage device stores test image data that includes a plurality of pairs each consisting of an object of the first color and an object of the second color and further includes, for each of the plurality of pairs, identification information for identification of the pair,   wherein a position of the object of the second color in the sub scanning direction in relation to the object of the first color differs from said pair to pair,   wherein the printing unit prints a test image on a sheet on a basis of the test image data read out of the storage device by the controller,   wherein the user interface receives the identification information from the user, and   wherein the controller updates the correction information on a basis of the identification information received via the user interface.   
     
     
         2 . The image forming apparatus according to  claim 1 ,
 wherein the test image is an image formed by printing the plurality of pairs in each of at least three areas arranged in a main scanning direction.   
     
     
         3 . The image forming apparatus according to  claim 2 ,
 wherein the user interface receives an input of the identification information individually for each of the at least three areas.   
     
     
         4 . The image forming apparatus according to  claim 3 ,
 wherein the controller updates the correction information using the identification information received individually for each of the at least three areas by the user interface.   
     
     
         5 . The image forming apparatus according to  claim 1 ,
 wherein the controller updates the correction information on a basis of information that represents distortion of the image of the second color and the identification information inputted via the user interface.   
     
     
         6 . The image forming apparatus according to  claim 5 ,
 wherein the printing unit includes a laser scanner unit for each color,   wherein the information that represents distortion is coordinate information based on distortion of a laser scanning line of the laser scanner unit, and   wherein the controller updates the correction information on a basis of a value calculated by adding, to the coordinate information, an amount of the print position shift in the sub scanning direction of the first color and the second color, which is determined from the identification information.   
     
     
         7 . The image forming apparatus according to  claim 5 ,
 wherein the controller updates the correction information on a basis of curve information obtained on a basis of the information that represents distortion and the identification information inputted via the user interface.   
     
     
         8 . The image forming apparatus according to  claim 1 ,
 wherein the test image data further includes a plurality of pairs each consisting of the object of the second color and an object of a third color and further includes, for each of the plurality of pairs, other identification information for identification of the pair,   wherein the controller reads the test image data on a basis of other correction information for correcting a print position shift in the sub scanning direction of the second color and the third color,   wherein the printing unit prints the test image on a basis of the test image data read by the controller,   wherein the user interface receives the other identification information from the user, and   wherein the controller updates the other correction information using, at least, the identification information and the other identification information received by the user interface.   
     
     
         9 . The image forming apparatus according to  claim 1 ,
 wherein the identification information is a numeral that means a relative position of the object of the first color and the object of the second color.   
     
     
         10 . The image forming apparatus according to  claim 1 ,
 wherein the user interface receives an input of the identification information for identifying, among the plurality of pairs in the test image printed, a pair for which a print position of the object of the first color coincides with a print position of the object of the second color.   
     
     
         11 . The image forming apparatus according to  claim 1 ,
 wherein the controller reads the test image data out of the storage device using the correction information, and   wherein the printing unit prints the test image on a basis of the test image data read by the controller.   
     
     
         12 . The image forming apparatus according to  claim 1 ,
 wherein the object of the first color is a line of the first color in the main scanning direction, and   wherein the object of the second color is a line of the second color in the main scanning direction.   
     
     
         13 . The image forming apparatus according to  claim 1 ,
 wherein, in the test images, the pairs are arranged at equal intervals in the sub scanning direction.   
     
     
         14 . The image forming apparatus according to  claim 1 ,
 wherein the controller updates the correction information on a basis of curve information based on the identification information received via the user interface.   
     
     
         15 . A control method for controlling an image forming apparatus,
 the image forming apparatus including,   a storage device configured to store image data,   a controller configured to read the image data out of the storage device on a basis of correction information for correcting a print position shift in a sub scanning direction of a first color and a second color,   a printing unit configured to print an image of the first color and an image of the second color on a basis of the image data read by the controller, and   a user interface configured to receive an input from a user,   the control method comprising:   printing a test image on a sheet on a basis of test image data that includes a plurality of pairs each consisting of an object of the first color and an object of the second color and further includes, for each of the plurality of pairs, identification information for identification of the pair, wherein a position of the object of the second color in relation to the object of the first color differs from said pair to pair;   receiving, via the user interface, the identification information included in the test image printed on the sheet; and   updating the correction information on a basis of the identification information received.   
     
     
         16 . An image forming apparatus, comprising:
 a storage device configured to store image data;   a controller configured to read the image data out of the storage device on a basis of correction information for correcting a print position shift in a sub scanning direction of an image of a first color and an image of a second color;   a printing unit configured to print the image of the first color and the image of the second color on a sheet on a basis of the image data read by the controller; and   a user interface configured to receive information from a user,   wherein the storage device stores test image data that includes a plurality of objects of a first color arranged in the sub scanning direction, a plurality of objects of a second color each printed at a distance in the sub scanning direction from the corresponding object of the first color, and further includes identification information for identification of the object of the second color each,   wherein a relative distance between the object of the first color and the object of the second color differs from one object pair to another,   wherein the controller reads the correction information on a basis of the test image data stored in the storage device,   wherein the printing unit prints a test image on a basis of the test image data read by the controller,   wherein the user interface receives the identification information from the user, and   wherein the controller updates the correction information on a basis of the identification information received via the user interface.   
     
     
         17 . The image forming apparatus according to  claim 16 ,
 wherein a print position of at least one of the objects of the second color is the same as a print position of one of the objects of the first color.