A Review on Lossless Compression Techniques for Wireless Capsule Endoscopic Data

Abstract

Background: The videos produced during wireless capsule endoscopy have larger data size causing difficulty in transmission with limited bandwidth. The constraint on wireless capsule endoscopy hinders the performance of compression module. Objectives: The objectives of this paper are as follows: (i) to have an extensive review on the lossless compression techniques and (ii) to find out the limitations of the existing system and the possibilities for improvement. Method: The literature review has been done with a focus on the compression schemes satisfying minimum computational complexity, less power dissipation and low memory requirements for hardware implementation. A thorough study on various lossless compression techniques is done under two perspectives, i.e., techniques applied on Bayer CFA and RGB images. The details of the various stages of wireless capsule endoscopy compression are looked into to have a better understanding. The suitable performance metrics for evaluating the compression techniques are listed from various literatures. Result: In addition to the Gastrolab database that is widely, WEO clinical endoscopy atlas and Gastrointestinal atlas found to be better alternatives for experimentation. Pre-processing operations, especially new subsampling patterns need to be given more focus to exploit the redundancies in the images. Investigations shows encoder module can be modified to bring more improvement towards compression. The real-time endoscopy still exists as a promising area for exploration. Conclusion: This review presents a research update on the details of wireless capsule endoscopy compression together with the findings as an eye-opener and guidance for further research.