Extraction of the Straight Line Segments from the Noisy Images as a Part of Pattern Recognition Procedure

摘要

The automated analysis of the images is of great importance today in many applications. In ultrasonic nondestructive evaluation of materials, the B- and C-scanning generates two-dimensional images which often require automated interpretation. Such images are often noisy and low-contrast. They are formed by combination of multiple ultrasonic waveforms obtained at different moments of investigation process or at different locations of the object of interest. The straight line segments are often formed on such images as a reflection of some physical phenomena taking place in the material. Such lines can sometimes be considered as the elements of more complex patterns when some a priory knowledge allows one to break the pattern into logical sub-elements. The suggested technique provides the way to recognize very low-contrast line segments on acoustical and other images when signal to noise ratio (SNR) is 1 and lower. At such SNR, the separation of real line from the noise artefacts becomes a challenging problem. The proposed technique provides the way of dealing with such problems by obtaining redundant amount of data from the area of interest using Radon transformation as the key part of the procedure.