Image correcting device, image forming apparatus, and image correcting method

An image forming apparatus comprising:

• a first calculating unit that calculates a blank position of dither matrixes used for performing a dither process on an image, the blank position being a position in the dither matrixes at which an image pattern is not present, based on a main-scanning size and an interval between the image patterns in the dither matrixes, the main-scanning size is a size of each of the dither matrixes in a main-scanning direction, and determines the blank position as one of image-shift possible positions, the image-shift possible positions are candidate positions where the image can be divided when performing skew-correction on the image;
• a second calculating unit that calculates an image dividing position where the image is divided when performing skew-correction on the image based on amounts of misregistration between a reference color and each of other colors in the image;
• a determining unit that compares the image-shift possible positions with the image dividing position and determines one of the image-shift possible positions closest to the image dividing position to be an image shift position;
• a correcting unit that performs skew-correction on the image by dividing the image at the image shift position to obtain a skew-corrected image;
• and
• an image forming unit that performs an image formation process by using the skew-corrected image.

An image correcting method comprising:

• calculating a blank position of dither matrixes used for performing a dither process on an image, the blank position being a position in the dither matrixes at which an image pattern is not present, based on a main-scanning size and an interval between the image patterns in the dither matrixes, the main-scanning size is a size of each of the dither matrixes in a main-scanning direction, and determines the blank position as one of image-shift possible positions, the image-shift possible positions are candidate positions where the image can be divided when performing skew-correction on the image;
• calculating an image dividing position where the image is divided when performing skew-correction on the image based on amounts of misregistration between a reference color and each of other colors in the image;
• comparing the image-shift possible positions with the image dividing position and determining one of the image-shift possible positions closest to the image dividing position to be an image shift position;
• and
• performing skew-correction on the image by dividing the image at the image shift position.