An image generating apparatus is provided with: first and second light sources that illuminate a material; an image sensor on which the material is disposed; a mask which includes a light-transmitting part that transmits light and a light-blocking part that blocks light, and which is positioned between the image sensor and the first and second light sources; and a light and dark image processing unit. The image sensor acquires first and second images of the material when illuminated by the first and second light sources, respectively. The light and dark image processing unit derives a difference between a luminance value of a pixel included in the first image and a luminance value of a pixel included in the second image at the same position as the pixel included in the first image, and thereby generates a third image of the material.