Defect Detection in Striped Images Using a One-Dimensional Median Filter

• Published in: Applied sciences 2020-02, Vol.10 (3), p.1012
• Main Authors: Lee, Wei-Chen, Tai, Pei-Ling
• Format: Article
• Language: English
• Subjects: Accuracy; Algorithms; defect detection; Defects; Genetic algorithms; Image processing; Light emitting diodes; Manufacturing industry; median filter; Methods; Neural networks; Quality assurance; stripe; Support vector machines; Wavelet transforms
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10031012

Defect detection is a key element of quality assurance in many modern manufacturing processes. Defect detection methods, however, often involve a great deal of time and manual work. Image processing has become widely used as a means of reducing the required detection time and effort in manufacturing. To this end, this study proposes an image-processing algorithm for detecting defects in images with striped backgrounds—defect types include scratches and stains. In order to detect defects, the proposed method first pre-processes images and rotates them to align the stripes horizontally. Then, the images are divided into two parts: blocks and intervals. For the blocks, a one-dimensional median filter is used to generate defect-free images, and the difference between the original images and the defect-free images is calculated to find defects. For the intervals, defects are identified using image binarization. Finally, the method superposes the results found in the blocks and intervals to obtain final images with all defects marked. This study evaluated the performance of the proposed algorithm using 65 synthesized images and 20 actual images. The method achieved an accuracy of 97.2% based on the correctness of the defect locations. The defects that could not be identified were those whose greyscales were very close to those of the background.