An image processing apparatus that generates image data for use in printing an image on a sheet stickable to a skin, comprising: an image acquirer that acquires a first skin image obtained by capturing an image of a skin at a first timing; an image analyzer that determines a discolored area extracted from the first skin image as a first discolored area; characterized in that the image acquirer acquires a second skin image obtained by capturing an image of the skin at a second timing later than the first timing; the image analyzer extracts a color of the skin from the second skin image; the apparatus also comprising: an image determiner that determines a cover area, to be covered with the sheet, in the second skin image based on the first discolored area and determines a color of the cover area based on the color of the skin; and a print controller that generates image data with a content for printing an image of the determined cover area on the sheet by using a coloring material of the determined color, wherein the image analyzer determines a discolored area extracted from the second skin image as a second discolored area, the image determiner makes a determination such that in a case where in the second discolored area, there exists a corresponding area corresponding to the first discolored area determined as the cover area before the second timing, the image determiner determines whether a predetermined condition is satisfied for the corresponding area; in a case where the predetermined condition is not satisfied, the image determiner does not adjust a predetermined threshold value while in a case where the predetermined condition is satisfied, the image determiner adjusts the predetermined threshold value so as to reduce the threshold value by a predetermined amount; and depending on whether a color difference between a color of the second discolored area and a color of a peripheral area outside the second discolored area is greater than or equal to the threshold value, the image determiner determines the second discolored area as the cover area or a non-cover area which is not to be covered with the sheet. an image acquirer that acquires a first skin image obtained by capturing an image of a skin at a first timing; an image analyzer that determines a discolored area extracted from the first skin image as a first discolored area; characterized in that the image acquirer acquires a second skin image obtained by capturing an image of the skin at a second timing later than the first timing; the image analyzer extracts a color of the skin from the second skin image; the apparatus also comprising: an image determiner that determines a cover area, to be covered with the sheet, in the second skin image based on the first discolored area and determines a color of the cover area based on the color of the skin; and a print controller that generates image data with a content for printing an image of the determined cover area on the sheet by using a coloring material of the determined color, wherein an image determiner that determines a cover area, to be covered with the sheet, in the second skin image based on the first discolored area and determines a color of the cover area based on the color of the skin; and a print controller that generates image data with a content for printing an image of the determined cover area on the sheet by using a coloring material of the determined color, wherein the image analyzer determines a discolored area extracted from the second skin image as a second discolored area, the image determiner makes a determination such that in a case where in the second discolored area, there exists a corresponding area corresponding to the first discolored area determined as the cover area before the second timing, the image determiner determines whether a predetermined condition is satisfied for the corresponding area; in a case where the predetermined condition is not satisfied, the image determiner does not adjust a predetermined threshold value while in a case where the predetermined condition is satisfied, the image determiner adjusts the predetermined threshold value so as to reduce the threshold value by a predetermined amount; and depending on whether a color difference between a color of the second discolored area and a color of a peripheral area outside the second discolored area is greater than or equal to the threshold value, the image determiner determines the second discolored area as the cover area or a non-cover area which is not to be covered with the sheet.