FEATURE CONVERSION DEVICE, SIMILAR INFORMATION SEARCH APPARATUS PROVIDED THEREWITH, CODING PARAMETER GENERATION METHOD, AND COMPUTER PROGRAM

A bit code converter transforms a learning feature vector using a transformation matrix updated by a transformation matrix update unit, and converts the transformed learning feature vector into a bit code. When the transformation matrix update unit substitutes a substitution candidate for an element of the transformation matrix, a cost function calculator fixes the substitution candidate that minimizes a cost function as the element. The transformation matrix update unit selects the element while sequentially changing the elements, and the cost function calculator fixes the selected element every time the transformation matrix update unit selects the element, thereby finally fixing the optimum transformation matrix. A substitution candidate specifying unit specifies the substitution candidate such that a speed of transformation processing that the bit code converter performs using the transformation matrix using the transformation matrix is enhanced based on a constraint condition stored in a constraint condition storage unit.