Detection of Low-contrast Defects in Optical Films Using Sigma-based Segmentation
Technique
邱奕契,吳智煒
Mechanical Engineering
Engineering
chiou@chu.edu.tw
Abstract
Optical film is an important component for LCDs, cell phones and other mobile
devices. It is crucial to ensure an optical films is defect-free. However, derive from
the inherent translucent characteristic, many images of defects of optical films are low
contrast. Low-contrast defects are notorious for their difficult to be detected. As some
low-contrast defects are barely visible to human being without special training, it is
indeed a challenging task to capture low-contrast defect images. To overcome the
difficulty, we thoroughly investigated various of imaging and lighting technologies.
After images have been captured successfully, we devided the captured defects, based
on their sizes, into two categories, i.e. macro defects and micro defects. To detect both
large and small defects, we set up a macro inspection system and a micro inspection
system, respectively. In the study, we provide an easy to understand approach to
reveal low-contrast defects. The experimental results showed that the proposed
inspection system and method is capable of detecting low-contrast defects such as
uneven coatings, streaks, white spots and foreign particles.
Keyword：Diffuser, Low-contrast Images, Defect Detection, Machine Vision