Coating defect detection method applying ultrasonic image

The invention relates to the technical field of data processing, in particular to a coating defect detection method applying an ultrasonic image, which comprises the following steps of: acquiring an internal image of a coating, and performing phase reversal processing on the internal image to obtain a corresponding phase reversal grayscale image; constructing an accumulation sequence curve and a column accumulation sequence curve; according to the row accumulation sequence curve and the column accumulation sequence curve, obtaining a defect area in the inverse gray level image; obtaining an internal image set, and constructing a gray level distribution curve of a defect middle row in the target internal image so as to calculate a peak distance discrete value and a symmetric value of the defect middle row; and calculating a fault ultrasonic attenuation discreteness parameter and an average gray level change rate of the target internal image to obtain a defect type index, and determining the defect type of the