Ultrasonic flaw detection has developed methods for recording and analyzing echo signals to determine the type of reflector and its dimensions. The method of digital focusing with an antenna (CFA) allows you to restore the image of the entire discontinuity boundary using echo signals reflected from the bottom of the control object, taking into account the transformation of the wave type. However, this approach is not always applicable in practice, since the shape of the bottom of the object of control may be unknown. Using the features of the behavior of the reflection coefficient for different types of waves, it is possible to draw a conclusion about the type of reflector from images only on a direct beam. Numerical and model experiments have confirmed the operability of the proposed approach.