1. An image processing apparatus, comprising: an outline extracting processing device configured to input a phase contrast image of a cell colony acquired by an observing device, and extract an outline of the cell colony, an extracting device configured to set, along the outline, a belt-like area with a predetermined width including the outline of the cell colony, the predetermined width of the belt-like area being defined by an outer belt line and an inner belt line, the outline being disposed between the outer belt line and the inner belt line and being spaced from the outer belt line and the inner belt line, the extracting device being further configured to extract a feature quantity of the outline of the cell colony based on a combination of brightness information of an inner area between the outline and the inner belt line and brightness information of an outer area between the outline and the outer belt line, and an automatic discriminating device configured to automatically discriminate whether or not the cell colony is an iPS cell colony based on a discriminant criterion determined in advance and the feature quantity extracted by the extracting device.