Following publication of the original article , the authors noted a typesetting mistake in the placement and numbering of equations (1) to (8).
The following paragraph in section 2.1.1 Pre-processing has been corrected by placing the first equation in the correct place. ‘In the median filter, the pixel value is selected by taking the middle section of the pixels. The median filter for the pixels (x, y) value means all the pixels will change to the median value of the neighborhood as in Eq. (1) .’