The invention relates to a method for extracting a face characteristic based on a local three-value mode, belonging to the technical field of
image processing. The method comprises the following steps of: firstly carrying out down sampling on an original face image to construct a face image
pyramid, then calculating LTP (long-term potentiation) characteristics of all the pixel points in an image at each layer, and then dividing the LTP characteristics of all the pixel points into positive LTP sub characteristics and negative LTP sub characteristics, respectively carrying out statistics to obtain a positive LTP sub characteristic value
histogram and a negative LTP sub characteristic value
histogram of the image at each layer in the face image
pyramid, and finally connecting vectors H+ and H- corresponding to the positive LTP sub characteristic value
histogram and the negative LTP sub characteristic value histogram as the final characteristic of the original face image I (x, y). In the invention, the local characteristic of the LTP characteristic and the statistics characteristics of all the local LTP characteristic histograms are utilized to realize uniformity of the local characteristic and global characteristic, and the LTP characteristic has a better inhibition effect on
noise compared with the LBP (local binary pattern) characteristic which is frequently adopted. The extracted characteristic has the characteristics of constant rotation and constant
grey scale, and face characteristic can be accurately extracted under the influences that illumination condition is changed, face expression is changed and a gesture is changed.