In an information processing apparatus, such as an image processing apparatus, positive samples and negative samples are learned by a number of weak classifiers. During learning by the weak classifiers, a value of weighted majority is calculated as a sum of products of the results of classification by the respective weak classifiers and associated weights, and a learning threshold is also calculated. When the number of negative samples is greater than or equal to one half of the number of positive samples, negative samples for which the value of weighted majority is less than the learning threshold are removed.