Method and apparatus for user authentication using face image

A user authentication apparatus using a face image, comprising:

• a frequency converting unit transforming a face image in a normalized spatial domain into frequency-domain data;
• a valid transform coefficient extracting unit extracting valid transform coefficients from the frequency-domain data based on energy-concentrated region information;
• a feature vector extracting unit extracting a feature vector from the extracted valid transform coefficients;
• and
• a user authentication unit performing user authentication by comparing the extracted feature vector with a previously registered feature vector,
• wherein the energy-concentrated region information comprises information regarding an energy concentration region having the transform coefficients with a high degree of redundancy, the energy concentration region being extracted using an energy probability map of the face image.

A method of extracting an energy-concentrated region, comprising:

• computing energy probabilities in individual face images for a plurality of prior training face images which are transformed into frequency-domain data;
• computing an energy probability map of the individual face images by selecting some of the computed energy probabilities which are equal to or greater than a predetermined energy value;
• and
• extracting an energy-concentrated region having transform coefficients that have a high degree of redundancy by using the energy probability map.