Image forming apparatus that controls fixing temperature

An image forming apparatus comprising:

• an image forming device that forms a toner image on a sheet using a plurality of colors, on a basis of image data;
• a fixing device that heats and presses the sheet on which the toner image has been formed;
• a transport device that transports the sheet to the image forming device and the fixing device;
• and
• a control device including a processor, and configured to act as a controller that controls a fixing temperature of the fixing device, when the processor executes a control program,
• the controller being configured to:
• execute a total pixel value acquisition process, including acquiring, with respect to each of the colors, a first total pixel value of a color, which is a total of the pixel value of the color, of each of a plurality of pixels, included in each of N×M pieces of blocks, defined by dividing the image data into a predetermined size;
• define A×B pieces of object blocks in the N×M pieces of blocks, by grouping a predetermined number of the blocks, according to data resolution of the image data, into one object block, and execute a total pixel value calculation process including calculating, with respect to each of the colors, a second total pixel value of a color, which is a total of the first total pixel value of the color, of the predetermined number of the blocks, included in each of the A×B pieces of object blocks;
• arrange the A×B pieces of object blocks such that A pieces of blocks are aligned along a transport direction of the sheet by the transport device, and B pieces of blocks are aligned along an orthogonal direction orthogonal to the transport direction, and execute an average value calculation process, including calculating a b-th average value (b being an integer between 1 and B−1, both ends inclusive), which is an average of a total of the second total pixel value of each of the plurality of colors, of each of the A pieces of object blocks, aligned in the transport direction at a position of a b-th object block in the orthogonal direction, and a total of the second total pixel value of each of the plurality of colors, of each of the A pieces of object blocks, aligned in the transport direction at a position of a (b+1)th object block in the orthogonal direction;
• and
• execute a fixing temperature setting process, including setting the fixing temperature of the fixing device to a predetermined first fixing temperature, when at least one of the b-th average values exceeds a predetermined threshold, and setting the fixing temperature of the fixing device to a fixing temperature, predetermined according to the b-th average value, and lower than the first fixing temperature, when none of the b-th average values exceed the predetermined threshold.