Exploration of Current Trend on Median Filtering Methods Utilized in Digital Grayscale Image Processing

Median filtering is a well known method to deal with impulse noise in digital images. However, due to some limitations associated with the standard median filtering approach, several new improved versions of the median filtering method have been proposed by researchers. The number of methods is expanding from year to year. Therefore, the purpose of this paper is to see the current trend of the median filtering techniques. The trend is observed from the available online literatures; which use or propose new median filtering methods. Because there are thousands of related reliable literatures available online alone, our research concentrates on online literatures only. These literatures were classified according to their search keywords. The scope of our research is limited to IEEExplore , ScienceDirect, and Google Scholar databases only. The results confirm that the research regarding to median filtering is still growing at this time. Furthermore, we observed that the weighted median filter is the most popular median filtering research, and it is followed by researches on the adaptive median filter. Based on ScienceDirect database, it is shown that all of the median filtering methods showing an increasing number of publications over year.