2. The learning device according to claim 1 , further comprising: a weight setting circuit that sets a weight of each learning image based on the classification result; and an error-rate calculation circuit that calculates an error rate of the weak classifier based on the classification result of each learning image according to the weak classifier and the weight, wherein the classifier generation circuit selects the weak classifier based on the error rate.
2. The learning device according to claim 1 , further comprising: a weight setting circuit that sets a weight of each learning image based on the classification result; and an error-rate calculation circuit that calculates an error rate of the weak classifier based on the classification result of each learning image according to the weak classifier and the weight, wherein the classifier generation circuit selects the weak classifier based on the error rate. 3. The learning device according to claim 2 , wherein the classifier generated by the classifier generation circuit is used for recognition of the detection target and another target different from the detection target.