Image forming apparatus and computer readable medium

An image forming apparatus comprising:

• an image correction unit that inserts a new pixel between pixels forming image data with a plurality of pixels printed using a plurality of print color materials arranged in a main scanning direction of each print color material of the plurality of print color materials in order to adjust the image width in the main scanning direction of each print color material of the plurality of print color materials;
• and
• a determination unit that determines whether or not the image data is specified for printing a watermark representing given information superposed,
• wherein, when the determination unit determines that the image data is specified for print with a portion of the watermark superposed, a prohibition unit included in the image correction unit prohibits insertion of the new pixel into a pixel string of a print color material of a similar color to the print color material used to print the portion of the watermark, of pixel strings printed using a plurality of print color materials arranged in the main scanning direction of each print color material of the plurality of print color materials, and
• wherein the prohibition unit prohibits insertion of the new pixel into the pixel string of a print color material only if the new pixel has a similar color to the print color material used to print the portion of the watermark.