1. An information retrieval apparatus comprising: an obtaining unit configured to obtain dynamic ranges and re-quantization codes of a target object to be retrieved and dynamic ranges and re-quantization codes of each of a plurality of comparison objects to be compared with the target object, the dynamic ranges and re-quantization codes of the target object and the dynamic ranges and re-quantization codes of the plurality of comparison objects being obtained as a result of adaptive dynamic range coding; a distance computation unit configured to compute distances between a same block of the target object and a corresponding block of each of the plurality of comparison objects using the obtained dynamic range and re-quantization codes of the same block of the target object and the obtained dynamic range and re-quantization codes of the corresponding block of the respective one of the plurality of comparison objects; and a comparison unit configured to compare distances between the target object and each of the plurality of comparison objects to select one of the comparison objects having a minimum distance.