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Median filter

This online calculator applies median filter to an image

The calculator below processes the loaded image with a median filter. The calculator allows you to set the size of the filter kernel - 3x3, 5x5, or 7x7. A median filter is usually used to remove "noise" from an image. You can read more about how the median filter works under the calculator.

PLANETCALC, Median filter

Median filter

Source image
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Source image

Median filter

For each processed pixel of the source image

  • calculate the luminosities of the neighbor pixels of the filter kernel (a square area that includes the processed pixel)
  • sort the luminosities in the numerical order
  • assign the median value (the value from the middle of the array) to the processed pixel in the resulting image

The median value is considered to be a more reliable "average" value for the color of the area than the actual average value since it is not affected by a random "noisy" pixel with a very different luminance value. And since the new pixel value is one of the existing values ​​in the area, the use of this filter does not give unrealistic pixels on sharp color transitions at the boundaries of objects.

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Creative Commons Attribution/Share-Alike License 3.0 (Unported) PLANETCALC, Median filter