Iimage forming apparatus, and method and non-transitory computer-readable medium for controlling same

An image forming apparatus comprising:

• a sheet feeder that includes a plurality of switchable sheet feed trays and feeds a recording medium from one sheet feed tray selected from the plurality of switchable sheet feed trays;
• a reading device that takes a reading of a dimension of the recording medium which is fed from the sheet feeder and on which an image has not been formed and outputs a reading value of the reading;
• an image forming device that forms an image on the recording medium;
• and
• a controller including a hardware processor and memory,
• wherein the controller performs a method comprising steps of:
• (i) for each of the plurality of switchable sheet feed trays, managing recording medium information of the sheet feed tray by associating the recording medium information with the sheet feed tray, the recording medium information being information on a recording medium stored in the sheet feed tray, the recording medium information configured to include a reference reading value registered as a reference for a reading value to be outputted by the reading device taking a reading of a recording medium fed from the sheet feed tray;
• (ii) when switching from a first sheet feed tray of the plurality of switchable sheet feed trays to a second sheet feed tray of the plurality of switchable sheet feed trays, selecting a sheet feed tray such that predetermined items of the recording medium information associated with the sheet feed tray match the predetermined items of the recording medium information associated with the first sheet feed tray as the second sheet feed tray;
• (iii) instructing the sheet feeder to switch from the first sheet feed tray to the second sheet feed tray;
• (iv) instructing the reading device to take a reading of a dimension of a recording medium fed from the second sheet feed tray as a second-tray reading value and output the second-tray reading value to the controller;
• (v) calculating a correction value of a position of an image to be formed on the recording medium fed from the second sheet feed tray based on a quantity of change in the second-tray reading value relative to the reference reading value registered in the recording medium information associated with the second sheet feed tray;
• and
• (vi) transmitting the correction value to the image forming device, and
• wherein the image forming device forms an image on the recording medium fed from the second sheet feed tray based on the correction value received from the controller.