An image processing apparatus (100, 200), comprising: a color image obtaining means configured obtain color image data representing a color image of biographic tissues; a lesion determining means configured to determine whether each pixel of the color image is of a lesion part based on the color image data; and a marking means configured to apply a mark indicating a position of the lesion part on the color image based on a result of determination, wherein the mark is configured such that the color image at a background of the mark can be seen, wherein the marking means is configured to apply the mark such that the mark does not completely cover the background but allows a part of the background to be seen through a space, characterized in that the lesion determining means comprises a score table generating means configured to generate a score table including, as an element, a score representing severity degree of lesion of the biographical tissue per each pixel of the color image; the marking means applies the mark indicative of a position and severity degree of the lesion part on the color image based on the score table; the marking means is configured to: set a mask which is a process target area within the color image; calculate a representative value of the score within the mask, wherein the representative value represents a severity degree of lesion of the biographic tissue; apply the mark to the mask based on the representative value; set the mask having a predetermined initial size; calculate the representative value regarding the mask having the predetermined initial size; change the size of the mask in accordance with the representative value; and apply the mark such that the mark inscribes in the mask of which size has been changed. a color image obtaining means configured obtain color image data representing a color image of biographic tissues; a lesion determining means configured to determine whether each pixel of the color image is of a lesion part based on the color image data; and a marking means configured to apply a mark indicating a position of the lesion part on the color image based on a result of determination, wherein the mark is configured such that the color image at a background of the mark can be seen, wherein the marking means is configured to apply the mark such that the mark does not completely cover the background but allows a part of the background to be seen through a space, characterized in that the lesion determining means comprises a score table generating means configured to generate a score table including, as an element, a score representing severity degree of lesion of the biographical tissue per each pixel of the color image; the marking means applies the mark indicative of a position and severity degree of the lesion part on the color image based on the score table; the marking means is configured to: set a mask which is a process target area within the color image; calculate a representative value of the score within the mask, wherein the representative value represents a severity degree of lesion of the biographic tissue; apply the mark to the mask based on the representative value; set the mask having a predetermined initial size; calculate the representative value regarding the mask having the predetermined initial size; change the size of the mask in accordance with the representative value; and apply the mark such that the mark inscribes in the mask of which size has been changed. set a mask which is a process target area within the color image; calculate a representative value of the score within the mask, wherein the representative value represents a severity degree of lesion of the biographic tissue; apply the mark to the mask based on the representative value; set the mask having a predetermined initial size; calculate the representative value regarding the mask having the predetermined initial size; change the size of the mask in accordance with the representative value; and apply the mark such that the mark inscribes in the mask of which size has been changed.