1. An image processing device comprising: a processor to: acquire a face image; create a converted face image by performing a first binarization process to the face image using a first threshold value; specify a face direction from a visual line direction of eyes in the acquired face image; detect a nose ridge in an area determined based on the specified face direction by performing a second binarization process using a second threshold value lower than the first threshold value, when the specified face direction is one of a left side direction and a right side direction; and add the detected nose ridge to the converted face image.