2. Xiamen Inspection Institute of Special Equipments，Xiamen 361000，China；

3. College of Chemistry and Chemical Engineering，Fuzhou University，Fuzhou 350108，China）

Abstract：Aiming at the problems of time of flight diffraction（TOFD） method which credibility of defect recognition influenced by personnel's experience and professional knowledge，an automatic recognition approach was proposed for TOFD image defects. Firstly，the Gabor wavelet of TOFD defects image characteristics was extracted，to reduce the dimension Gabor features，the principal component analysis（PCA）technique has been used based on these characteristics. Then，the Fisher linear discriminant analysis method was used to analysis，at last，the actual system and the test sample on the test verification has been established for testing. Experiment in the 109 training samples and 25 test samples which comes from artificials and natural defects，compared Gabor wavelet features with characteristics of the original image pixel defect classifier recognition rate in test. The results indicate that the rate of recognition based on Gabor wavelet feature is 72%，it has higher rate of recognition than the method based on the original image pixel.

Key words：time of flight diffraction（TOFD）；Gabor wavelet；Fisher；linear discriminant analysis；principal component analysis（PCA）