Median Filters

The median filter functions perform non-linear filtering of a source image data.

These functions use either an arbitrary rectangular mask, or the following predefined masks of the IppiMaskSize type to filter an image:

ippMskSize3x1	Horizontal mask of length 3
ippMskSize5x1	Horizontal mask of length 5
ippMskSize1x3	Vertical mask of length 3
ippMskSize3x3	Square mask of size 3
ippMskSize1x5	Vertical mask of length 5
ippMskSize5x5	Square mask of size 5

The size of the neighborhood and coordinates of the anchor cell in the neighborhood depend on the mask mean value. Table “Median Filter Mask, Neighborhood, and Anchor Cell” lists the mask types with the corresponding neighborhood sizes and anchor cell coordinates. Mask size in mask names is indicated in (XY) order. The anchor cell is specified by its coordinates anchor.x and anchor.y in the coordinate system associated with the upper left corner of the mask.

Median filters have the effect of removing the isolated intensity spikes and can be used to reduce noise in an image.

For details on algorithms used in Intel IPP for median filtering, see [APMF].

• FilterMedianBorderGetBufferSize
  Computes the size of the work buffer for the FilterMedianBorder function.
• FilterMedianBorder
  Performs median filtering of an image.
• FilterMedianGetBufferSize
  Computes the size of the external buffer for ippiFilterMedian function.
• FilterMedian
  Filters an image using a median filter.
• FilterMedianCross
  Filters an image using a cross median filter.
• FilterMedianWeightedCenter3x3
  Filters an image using a median filter with a weighted center pixel.
• FilterMedianColor
  Filters an image using a color median filter.