Mediaanisuodin

Mediaanisuodin is a non-linear digital filter used in image and signal processing. It operates by replacing each data point in a set with the median value of its neighboring data points within a defined window. This process effectively smooths out noise while preserving sharp edges better than linear smoothing filters like the Gaussian filter. The window size is a crucial parameter, determining the extent of smoothing. A larger window will result in more smoothing but can also blur finer details.

The core operation of a median filter involves sorting the values within the window and selecting the middle value. For a window of odd size, the median is straightforward to find. For an even-sized window, a common approach is to average the two middle values, though other strategies exist. This median operation is particularly effective at removing salt-and-pepper noise, which consists of random black and white pixels, because these extreme values are less likely to be the median of their surrounding pixels.

Median filters are widely applied in various fields. In digital imaging, they are used for noise reduction in photographs, medical imaging, and computer vision. In signal processing, they can help denoise time-series data, such as sensor readings. The computational cost of a median filter is generally higher than that of linear filters due to the sorting required for each window, but its effectiveness in specific noise scenarios makes it a valuable tool.