A two-stage identification method based on sketch entity identification and the perceptual hashing technique is proposed to overcome the defect of strong randomness and excessive freedom in handwritten sketches and balance the overall properties and local characteristics of a sketch. First

the geometrical characteristics of the stroke

the stroke order

and the stroke structural characteristics of the input handwritten sketch are extracted. Second

a semantic library of sketches containing information on entity

stroke structure

and stroke order is searched to recognize a sketch composed of a regular geometric entity. If no proper sketch is available in the library

an image of asketch is generated and recognition of the sketch image is implemented with perceptual hashing technology. With the sketch recognition method proposed in this paper

recognition of 150 types of sketches in a database was achieved; the average recognition rate is 82.6%. Experimental results show that the proposed method has a high recognition rate for any handwritten sketch of database input by different users. The method also allows for extensive identification of other sketches by adding sketch types to the semantic library of sketches and the database.