Image forming apparatus and image forming method

An image forming method for an image forming apparatus including an image forming unit which forms an image constituted of a color toner image and a clear toner image on a sheet, the image forming unit including a color image forming unit which uses a color toner to form the color toner image and a clear image forming unit which uses a clear toner to form the clear toner image, the image forming method comprising:

• a first calculation step of calculating a summed height of the color toner image formed on the sheet by summing up a height of the color toner image on the basis of input image data;
• a second calculation step of calculating, on the basis of a target value for glossiness stored in a storage unit in advance, a target total height of the color toner image and the clear toner image to realize the target value for glossiness;
• a third calculation step of calculating a height of the clear toner image by subtracting the summed height of the color toner image from the target total height of the color toner image and the clear toner image;
• and
• an adjustment step of adjusting, on the basis of the calculated height of the clear toner image, the height of the clear toner image formed on the sheet by the image forming unit.

An image forming apparatus comprising:

• an image forming unit which forms an image constituted of a color toner image and a clear toner image on a sheet, the image forming unit including:
• a color image forming unit which uses a color toner to form the color toner image;
• and
• a clear image forming unit which uses a clear toner to form the clear toner image;
• a glossiness detection unit which detects glossiness of the image formed on the sheet;
• a glossiness adjustment unit which (i) generates image data for a detection-use pattern image including a color toner pattern and a clear toner pattern in such a way that a total toner adhesion amount of the color toner and the clear toner obtained by summing up a toner adhesion amount of the color toner and a toner adhesion amount of the clear toner makes a predetermined target value for glossiness so as to make the glossiness in all pixels uniform, (ii) makes the image forming unit form the detection-use pattern image by shifting a forming position of the clear toner pattern with respect to a forming position of the color toner pattern stepwise on the basis of the image data for the detection-use pattern image, (iii) makes the glossiness detection unit detect the glossiness of the detection-use pattern image, and (iv) obtains, on the basis of the forming position of the clear toner pattern when the glossiness detected by the glossiness detection unit reaches the target value for glossiness, forming position information on a forming position of the clear toner image with respect to a forming position of the color toner image;
• and
• a control unit which (i) generates image data for the clear toner on the basis of input image data in such a way that the total toner adhesion amount of the color toner and the clear toner makes the target value for glossiness so as to make the glossiness in all pixels uniform, and (ii) when the image forming unit forms the image on the sheet on the basis of the input image data and the image data for the clear toner, controls the forming position of the clear toner image with respect to the forming position of the color toner image on the basis of the forming position information obtained by the glossiness adjustment unit.