Reduction of bubble-like frames using a RSS filter in wireless capsule endoscopy video

Abstract

Wireless capsule endoscopy (WCE) is an advanced technique for inner visualization of the digestive tract. However, its large amount of video data collected continuously for several hours by wireless image sensors usually results in tiresome and tedious reading for physicians. To develop this technique in practice, the automatic reduction of large amounts of video data arises as a helpful alternative, which is partly implemented by detecting the non-useful frames, such as those filled with intestinal juices accompanying large bubble-like regions. Based on the bubbles’ morphology properties, a novel automatic approach for detecting the bubble-like frames in capsule video endoscopy that is based on a new ring shape selective (RSS) filter is presented. According to the shape of the bubbles’ bright ring boundary, a group of the shape probability functions and the response intensity functions produced by Hessian matrix eigenvalues are used to construct the RSS filters to enhance the boundary areas of the bubbles. Then, the bubble-like frames can be distinguished by in the bright areas after binary and morphological processing in the filtered images. The experimental results show that the uninformative bubble-like frames can be detected effectively by this approach even under non-uniform illumination conditions.