a two dimensional image storing means for storing a lighting information texture which has a base texture for mapping a detail of each object disposed in the virtual three dimensional space, color information for at least mapping a diffuse reflection from a surface of the object and a shadow of the object, and mask information for masking a dark region including the shadow;

a texture mapping means for mapping a diffuse reflection from a first object and a second object and a shadow of the first object on the second object, which are generated by a virtual light from the virtual light source hitting the first object and the second object, to a target object by superimposing the diffuse reflection and the shadow on the base texture based on the lighting information texture;

a specular reflection generating means for generating a specular reflection to surfaces of the first object and the second object by calculating a mirror reflection of the first and second object which is generated by the virtual light; and

a light masking means for masking the specular reflection based on the mask information provided in the lighting information texture which is mapped to the second object,

wherein the objects composed of polygons are discernibly set to be a movable object which moves in the virtual three dimensional space or a fixed object which is fixed in the virtual three dimensional space or is in a constant position relationship with the virtual light source, and the image generating apparatus further comprises determining means for determining whether a target object to be processed is the fixed object or not, and only when the determining means determines that the target object is the fixed object, a mapping process for the diffuse reflection and the shadow is performed by using the lighting information texture.