Method and apparatus for printing with different sheet feeding amounts and accuracies

A method of forming a plurality of raster lines with a head, each of the raster lines comprising an array of dots aligned in one direction of a printing medium or in a raster-forming direction, and carrying out a sub-scan that moves said head in another direction crossing the raster-forming direction or in a sub-scanning direction relative to said printing medium, thereby printing an image corresponding to input image data on said printing medium,

• said head having n nozzles configured to create dots of an identical color and arranged in the sub-scanning direction at a fixed interval, where n denotes an integer of not less than 2;
• said method comprising the steps of:
• (a) carrying out the sub-scan by a first feeding amount with a first accuracy to record a portion the image in a first area on said printing medium;
• and
• (b) carrying out the sub-scan by a second feeding amount with a second accuracy, which is lower than the first accuracy, to record the image in a second area on said printing medium to complete recording of the image,
• wherein said step (a) carries out the sub-scan by the first feeding amount that allows adjoining raster lines to be formed with different nozzles in a predetermined section of the first area that does not adjoin to the third area, and carries out the sub-scan by a third feeding amount, which is smaller than the first feeding amount and which differs from the second feeding amount, in a middle area on said printing medium that adjoins to both the predetermined section of the first area and the second area.

A recording medium, in which a program for causing a printer to form raster lines and carry out a sub-scan in order to print an image corresponding to image data on a printing medium is recorded in a computer readable manner,

• said program causing a computer to carry out the functions of:
• dividing a printable area, in which the image can be recorded, into a first area where the sub-scan is carried out by a first feeding amount with a first accuracy, to record a portion of the image in the first area, and a second area where the sub-scan is carried out by a second feeding amount with a second accuracy, which is lower than the first accuracy, to complete recording of the image in the second area;
• outputting a first control signal to carry out the sub-scan by the first feeding amount that allows adjoining raster lines to be formed with different nozzles in a predetermined section of the first area that does not adjoin to the second area;
• and
• outputting a second control signal to carry out the sub-scan by a third feeding amount, which is smaller than the first feeding amount and which differs from the second feeding amount, in a middle area of the printable area that adjoins both to the predetermined section of the first area and to the second area.