Apparatus and method for evaluating quality of granular objects

A quality evaluation method for granular objects includes the steps of: irradiating (30,34,38) the objects (26) from a front side and a back side thereof; taking (31,35) a reflection light image and a transmission light image from both the front and back sides of the irradiated objects; obtaining (3) optical information of the objects by image-processing the reflection and transmission light images; obtaining (3) shape information of the objects based on the optical information; determining (4) the quality of each of the objects based on the optical information and the shape information; and counting (4) the numbers of the objects per quality and obtaining ratios of the objects per quality against the total number of the objects. Samples images of the objects per quality are prepared. The numbers and ratios of the objects per quality and the sample images are displayed (6) or printed out (5). One side of the granular objects may be irradiated by separate light sources (34A-34D) that are turned on/off simultaneously or independently with each other. The separate light sources, in combination, form a circular or ring-like light source. By so doing, the detection of crack in the object is highly enhanced.